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USAAAO — 2014 National Astronomy Olympiad
Question 1
Which of the following constellations are visible during the summer?
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 2
Which stars make up the Winter Triangle asterism?
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 3
The moon is at its upper culmination at 8pm, mean solar time. Estimate the phase of the moon.
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 4
Arrange the following stages of the life cycle of a star of one solar mass in chronological order - Red-giant branch, Pl...
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 5
How are the rings of Saturn thought to be formed?
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 6
The James Webb Space Telescope is to be sent to the second Lagrange point of the Earth-Sun system. What is the significa...
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 7
Which of the following is not a possible method of detecting exoplanets?
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 8
An 8 inch Dobsonian telescope with a focal ratio of f/6 is used with a 12mm Plossel eyepiece. Calculate the magnifying p...
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 9
Approximately how much higher is the limiting magnitude of a telescope than that of the human eye? Assume that the teles...
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 10
What is the advantage of an Equatorial telescope mount as compared to an Alt-az mount?
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 11
Alberio (β Cygni) is a double star system in the constellation Cygnus. The magnitudes of the component stars Alberio A &...
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 12
Which of the following stars is circumpolar in Romania (44°25'N 26°06'E)? (Circum-polar stars are stars that never set).
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 13
Haley's comet last appeared in the night sky in 1986. The Perihelion and Aphelion of its orbit are given by 0.586AU & 35...
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 14
What would be the maximum speed of a meteor on a parabolic orbit around the sun, whose point of closest approach is 1AU?
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 15
Estimate the lifespan of the Sun. (Mass of H : 1.00794u; Mass of He : 4.002602u)
Open questionUSAAAO — 2014 National Astronomy Olympiad
Question 16
Calculate the length of the shortest day that can be experienced in Romania (44°25'N 26°06'E). (Earth's axial tilt is 23...
Open questionUSAAAO — 2015 Practice Round
Question 1
Light from distant galaxies appears to be:
Open questionUSAAAO — 2015 Practice Round
Question 2
Given a star of 70 solar masses and 20 solar radii, what type of star is this?
Open questionUSAAAO — 2015 Practice Round
Question 3
The Sun has three major zones in its interior. What are these three zones, listed from center of the Sun outward?
Open questionUSAAAO — 2015 Practice Round
Question 4
The latitude and longitude of LA are 34.05 degrees N and 118.25 degrees W, respectively. A star at which of the followin...
Open questionUSAAAO — 2015 Practice Round
Question 5
The semi-major axis of an asteroid in the asteroid belt is 3 AU. What is its orbital period, in years?
Open questionUSAAAO — 2015 Practice Round
Question 6
What object is left at the middle of a planetary nebula, and what is the largest mass at which this object can exist?
Open questionUSAAAO — 2015 Practice Round
Question 7
The mean orbital velocity of Jupiter is 13.1 km/s, its mass is 1.9 × 10²⁷ kg, and its orbit has a semi-major axis of 7.9...
Open questionUSAAAO — 2015 Practice Round
Question 8
In a distant solar system, two planets, A and B, orbit a central main sequence star, like our sun. A day on Planet A las...
Open questionUSAAAO — 2015 Practice Round
Question 9
Which of the Solar System planets causes the “Kirkwood Gaps” found in the asteroid belt?
Open questionUSAAAO — 2015 Practice Round
Question 10
Calculate the escape velocity from a planet with twice the mass and 1/3 the radius of Earth.
Open questionUSAAAO — 2015 Practice Round
Question 11
Two neutron stars, each with a mass of 3 solar masses, merge to form a black hole. Assuming no mass is lost, find the ra...
Open questionUSAAAO — 2015 Practice Round
Question 12
What size telescope is needed to resolve Hellas Planitia (a 2,300 km wide crater) on Mars through a v-band filter (effec...
Open questionUSAAAO — 2015 Practice Round
Question 13
Fifteen minutes after sunset, you look west and see the moon rising. What phase is the moon in?
Open questionUSAAAO — 2015 Practice Round
Question 14
When taking the spectrum of a galaxy with redshift z=1, the H-alpha line (λ=656 nm) appears at what wavelength?
Open questionUSAAAO — 2015 Practice Round
Question 15
Which of the following Messier objects is grouped incorrectly with its type and constellation?
Open questionUSAAAO — 2015 Practice Round
Question 16
Star X has an apparent magnitude of 5.7 and is located 26.3 pc from the Sun. If there are 2.0 magnitudes of extinction t...
Open questionUSAAAO — 2015 Practice Round
Question 17
In a nearby star system, two stars are seen to orbit each other every 8 years. At their closest, the stars are 2” apart....
Open questionUSAAAO — 2015 Practice Round
Question 18
The Triangulum Galaxy has coordinates (RA: 1.564h, Dec: 30.660°). Which answer is closest to the local time at which it...
Open questionUSAAAO — 2015 Practice Round
Question 19
The peak wavelength of radiation from a certain star is 644 nm. If the absolute magnitude of this star is -0.17, what is...
Open questionUSAAAO — 2015 Practice Round
Question 20
Jupiter has a mass of 1.9 × 10²⁷ kg and a semimajor axis of 5.2 AU. Assume someone “out there” can resolve star position...
Open questionUSAAAO — 2015 First Round
Question 1
At arms length, the width of a fist typically subtends how many degrees of arc?
Open questionUSAAAO — 2015 First Round
Question 2
To have a lunar eclipse, the line of nodes must be pointing at the sun. The moon must also be in what phase?
Open questionUSAAAO — 2015 First Round
Question 3
Mars orbits the sun once every 687 days. Suppose Mars is currently in the constellation Virgo. What constellation will i...
Open questionUSAAAO — 2015 First Round
Question 4
To calculate the field of view of a telescope, you measure the time it takes Capella (RA:5.27h, dec:45.98°) to pass acro...
Open questionUSAAAO — 2015 First Round
Question 5
A telescope with focal length of 20 mm and aperture of 10 mm is connected to your smartphone, which has a CCD that measu...
Open questionUSAAAO — 2015 First Round
Question 6
What is its the resolution in arcseconds per pixel?
Open questionUSAAAO — 2015 First Round
Question 7
Comet 67P/Churyumov–Gerasimenko has an orbital period around the Sun of 6.44 years. What is its semimajor axis, in AU?
Open questionUSAAAO — 2015 First Round
Question 8
Which of the following techniques most directly constrains the mass of an exoplanet?
Open questionUSAAAO — 2015 First Round
Question 9
Which two properties of galaxies does the Tully-Fisher relation utilize a correlation between?
Open questionUSAAAO — 2015 First Round
Question 10
A binary star system has two components: Star A and Star B. Star A has a mass of 5 solar masses, and Star B has the same...
Open questionUSAAAO — 2015 First Round
Question 11
What is, approximately, the peak wavelength of electromagnetic radiation emitted by a star at a temperature of 5,000 K?
Open questionUSAAAO — 2015 First Round
Question 12
Stars A and B are observed over a period of 1 year. Both stars appear to move with respect to the background stars from...
Open questionUSAAAO — 2015 First Round
Question 13
Suppose that you measure the parallax angle for a particular star to be 0.25 arcsecond. The distance to this star is
Open questionUSAAAO — 2015 First Round
Question 14
On the main sequence, stars obtain their energy
Open questionUSAAAO — 2015 First Round
Question 15
Star A has a radius that is 2 times larger than the radius of star B, and a surface temperature that is 2 times smaller...
Open questionUSAAAO — 2015 First Round
Question 16
A and B, two main sequence stars of the same spectral class, have apparent magnitudes of 17 and 12, respectively. If sta...
Open questionUSAAAO — 2015 First Round
Question 17
Given that dark energy is vacuum energy, and that the densities of dark energy, dark matter and normal matter in the uni...
Open questionUSAAAO — 2015 First Round
Question 18
A type Ia supernova was observed in a galaxy with a redshift of 0.03. The supernova was determined to be 1.3 × 10⁸ pc aw...
Open questionUSAAAO — 2015 First Round
Question 19
In a main sequence star, gravitational collapse is counteracted by:
Open questionUSAAAO — 2015 First Round
Question 20
If the hydrogen alpha line of a star, normally 656.3 nm, is observed to be 662.5 nm, what is the star’s radial speed rel...
Open questionUSAAAO — 2015 First Round
Question 21
Within M-type stars, heat transfer occurs primarily through:
Open questionUSAAAO — 2015 First Round
Question 22
If a 1.2 solar mass star shows a radial velocity variation with a period of 9.2 days and amplitude of 32 m/s, estimate t...
Open questionUSAAAO — 2015 First Round
Question 23
Calculate the total angular distance swept by Venus (a = 0.7 AU) during the flight time of a probe completing a Hohmann...
Open questionUSAAAO — 2015 First Round
Question 24
Calculate the blackbody equilibrium temperature of Mars. Take Mars’s albedo to be 0.25 and semimajor axis to be 1.5 AU
Open questionUSAAAO — 2015 First Round
Question 25
Calculate the semimajor axis of a satellite orbiting the Earth with a velocity of 8.3 km/s at a distance of 300 km from...
Open questionUSAAAO — 2015 First Round
Question 26
On the night of December 23rd-24th 2015, an occultation of a bright star by the moon will be visible from Britain to Jap...
Open questionUSAAAO — 2015 First Round
Question 27
A synodic day on Mars is 24 hours and 40 minutes. If one Martian year is 687 earth-days, which of the following is close...
Open questionUSAAAO — 2015 First Round
Question 28
Suppose at the equator, a star passes through the zenith at local noon on the summer solstice. What is the right ascensi...
Open questionUSAAAO — 2015 First Round
Question 29
40 light years away, an exoplanet orbits a star of 5 solar masses every 14 years. Assuming this system has an inclinatio...
Open questionUSAAAO — 2015 First Round
Question 30
A planet orbits a star with a projected semimajor axis of 0.24”. What is the necessary aperture size of a telescope than...
Open questionUSAAAO — 2016 First Round
Question 1
All RR Lyrae variables have an absolute magnitude M of approximately 0.75. If an RR Lyrae star is observed with an appar...
Open questionUSAAAO — 2016 First Round
Question 2
If the closest distance from a planet to its host star is 1.50 AU and its farthest distance from its host star is 4.50 A...
Open questionUSAAAO — 2016 First Round
Question 3
A star exhibits periodic variations in brightness suggestive of a transiting companion. If the minimum stellar flux is 9...
Open questionUSAAAO — 2016 First Round
Question 4
Suppose you are on the surface of the Moon, and you want to launch an object into an elliptic orbit with a perilune of 1...
Open questionUSAAAO — 2016 First Round
Question 5
Estimate the minimum mass of a galaxy with a radius of 40,000 ly if stars at the edge of the galaxy orbit with a velocit...
Open questionUSAAAO — 2016 First Round
Question 6
Estimate the mass of an old globular cluster if the escape velocity at the edge of the cluster is 8.5 km/s. The cluster...
Open questionUSAAAO — 2016 First Round
Question 7
What delta V must an earth orbiting spacecraft apply to transfer from a 200 km parking orbit to a transfer orbit with an...
Open questionUSAAAO — 2016 First Round
Question 8
Suppose a probe has a velocity of 20 km/s when it’s 100 AU away from the Sun. What type of orbit is the probe on? The Su...
Open questionUSAAAO — 2016 First Round
Question 9
Phobos orbits around 9,376 km away from the center of its host planet, Mars, and has an orbital period of 8 hours. What...
Open questionUSAAAO — 2016 First Round
Question 10
Mercury’s orbit around the Sun has a semimajor axis of 0.387 AU. Knowing that the mass of the Sun is 1.99*10³⁰ kg and as...
Open questionUSAAAO — 2016 First Round
Question 11
Mercury’s orbit has a semimajor axis of 0.387 AU. What would be the maximum angular separation between Mercury and the S...
Open questionUSAAAO — 2016 First Round
Question 12
A geostationary satellite orbits Earth so that it appears at all times to be at the Zenith as viewed from a fixed point...
Open questionUSAAAO — 2016 First Round
Question 13
What would be the angular size of the sun as seen from Mars in arcminutes? Assume Mars orbits at a distance of 1.5 AU. (...
Open questionUSAAAO — 2016 First Round
Question 14
Only some stars rise (cross the horizon from below) due East (at Azimuth 90°). For an observer at Latitude 37°, Longitud...
Open questionUSAAAO — 2016 First Round
Question 15
On March 3, 2012, Mars experienced retrograde motion. The configuration of the Sun, Mars, and Earth that led to retrogra...
Open questionUSAAAO — 2016 First Round
Question 16
Suppose there are two main-sequence stars, A and B. Star A has a temperature of 10,000 K, while Star B has a temperature...
Open questionUSAAAO — 2016 First Round
Question 17
An active galactic nucleus is observed to produce a hydrogen emission line at 687.2 nm. The rest wavelength of this hydr...
Open questionUSAAAO — 2016 First Round
Question 19
Suppose the absolute magnitude of a star is 3.25. What would its apparent magnitude be as seen from a planet orbiting th...
Open questionUSAAAO — 2016 First Round
Question 20
Which of these is the correct sequence of events in the Universe, from earliest to latest?
Open questionUSAAAO — 2016 First Round
Question 21
Suppose a star has an absolute bolometric magnitude of -0.77 and a bolometric correction of -1.02. If it has an apparent...
Open questionUSAAAO — 2016 First Round
Question 22
A planet orbits a star with a temperature of 6500K and a radius of 1.2 solar radii at a distance of 1.5 A.U. The planet...
Open questionUSAAAO — 2016 First Round
Question 23
Which constellation is not on the Zodiac?
Open questionUSAAAO — 2016 First Round
Question 24
One of the constellations that will be visible in Bhubaneshwar, India (20° 16’ 20.67” N, 85° 50’ 1.85” E) in December 20...
Open questionUSAAAO — 2016 First Round
Question 25
Which of the following famous Messier objects is in the constellation Hercules?
Open questionUSAAAO — 2016 First Round
Question 27
Which of the following famous Messier objects is in the constellation Orion?
Open questionUSAAAO — 2016 First Round
Question 28
What is the brightest star in the constellation Taurus?
Open questionUSAAAO — 2016 First Round
Question 29
What is the brightest star in the constellation Perseus?
Open questionUSAAAO — 2016 First Round
Question 30
Which of these Messier objects is NOT in the constellation Auriga?
Open questionUSAAAO — 2016 First Round
Question 31
To which constellation does your previous response belong?
Open questionUSAAAO — 2016 First Round
Question 32
What type of object is M44?
Open questionUSAAAO — 2016 First Round
Question 33
To which constellation does M44 belong?
Open questionUSAAAO — 2016 First Round
Question 34
Which three stars make up the Summer Triangle?
Open questionUSAAAO — 2017 First Round
Question 1
What would be the radius of the Sun when it becomes a black hole (although the probability is almost zero)?
Open questionUSAAAO — 2017 First Round
Question 2
A comet called “SMukherjee2017” which has physical values of e = 0.12, a = 4AU was visible from the Earth in 2017. In wh...
Open questionUSAAAO — 2017 First Round
Question 3
What is the perihelion of comet “SMukherjee2017”?
Open questionUSAAAO — 2017 First Round
Question 4
A comet called “LQi2017” which has physical values of e = 1.2, a = 19AU was visible from the Earth in 2017. In which yea...
Open questionUSAAAO — 2017 First Round
Question 5
How far away is the horizon from you, when your height is about 5ft 11in (1.8m)? You are standing on a plain that has no...
Open questionUSAAAO — 2017 First Round
Question 6
Consider that the absolute magnitude of a star is m₀. Imagine that the first star gets split into N smaller identical st...
Open questionUSAAAO — 2017 First Round
Question 7
Taking the radius of the black hole to be the Schwarzschild radius (the radius at which the escape velocity of an object...
Open questionUSAAAO — 2017 First Round
Question 8
In 1974, Stephen Hawking proved that black holes emit blackbody radiation according to the Stefan-Boltzmann law (due to...
Open questionUSAAAO — 2017 First Round
Question 9
We observe that a quasar’s brightness varies within less than a day. What is the best upper bound on the quasar’s size t...
Open questionUSAAAO — 2017 First Round
Question 10
A student group from California Institute of Technology is planning a massive prank for this year. This year, they are p...
Open questionUSAAAO — 2017 First Round
Question 11
The MIT students have found out about the plans of the Caltech students of sending a rocket to fly a parachute above the...
Open questionUSAAAO — 2017 First Round
Question 12
The following series of photos were taken on March 17 around noon time (each photo taken about 3 minutes apart from the...
Open questionUSAAAO — 2017 First Round
Question 13
Imagine you are at the South Pole on December 21st. Which of these statements best describes your shadow on this day?
Open questionUSAAAO — 2017 First Round
Question 14
The USAAAO team successfully launched a satellite to be in the orbit within the boundary of the Solar System. The satell...
Open questionUSAAAO — 2017 First Round
Question 15
At which of the following phases of the Moon’s orbit is the tidal bulge of Earth largest?
Open questionUSAAAO — 2017 First Round
Question 16
A predicted (A) and observed (B) rotation curve of a typical spiral galaxy is shown below. What component of the galaxy...
Open questionUSAAAO — 2017 First Round
Question 17
What is a star burning in its core when it is on the horizontal branch?
Open questionUSAAAO — 2017 First Round
Question 18
What is the final stage in the evolution of a G1 star with mass of 1.1MSun?
Open questionUSAAAO — 2017 First Round
Question 19
The following graph shows spectral flux density as a function of wavelength for the 2 stars in a binary system. Assume t...
Open questionUSAAAO — 2017 First Round
Question 20
What is the ratio of the radius of the hotter star to that of the colder star?
Open questionUSAAAO — 2017 First Round
Question 21
Given that the apparent magnitude of the system is 8.2, what is the apparent magnitude of the brighter star?
Open questionUSAAAO — 2017 First Round
Question 22
Assuming that the radius of the smaller star is 2 solar radii, what is the distance to the system? [Answer choices updat...
Open questionUSAAAO — 2017 First Round
Question 23
Astronomers have observed the Cosmic Microwave Background (CMB) radiation. Which of these is a correct description of th...
Open questionUSAAAO — 2017 First Round
Question 24
Which is the correct chronological order of events?
Open questionUSAAAO — 2017 First Round
Question 25
Edwin Hubble published in 1929 the paper “A Relation Between Distance and Extragalactic Nebulae” explaining his find tha...
Open questionUSAAAO — 2017 First Round
Question 26
An astronomical interferometer is an array of separate radio telescope antennas that work together as a single telescope...
Open questionUSAAAO — 2017 First Round
Question 28
Choose the values (x, y, z) that would best complete the descriptions below for the 3 different types of twilights. i) c...
Open questionUSAAAO — 2017 First Round
Question 29
The Small Magellanic Cloud is located in the southeast corner of which of the following constellations:
Open questionUSAAAO — 2017 First Round
Question 30
Due to the precession of the equinoxes, the north and south celestial poles trace out circles on the celestial sphere wi...
Open questionUSAAAO — 2017 First Round
Question 31
What is the 13’th constellation that crosses the ecliptic, which is not included in the 12 zodiacal constellations?
Open questionUSAAAO — 2018 First Round
Question 1
A planet’s orbit around a star has a semimajor axis of 16 AU. What is the period of the planet’s orbit?
Open questionUSAAAO — 2018 First Round
Question 2
Which of the following has the longest wavelength?
Open questionUSAAAO — 2018 First Round
Question 3
What is the peak wavelength in Angstroms (Å) of electromagnetic radiation emitted by a star at a temperature of 10,000 K...
Open questionUSAAAO — 2018 First Round
Question 4
Determine the azimuth of Capella (Aurigae) in its upper culmination as seen from geographic latitude of φ = +45°58′.
Open questionUSAAAO — 2018 First Round
Question 5
From which geographic latitude does the star Antares (α Scorpii, δ = −26°19′) never rise?
Open questionUSAAAO — 2018 First Round
Question 6
For the following problem find the range in which the answer lies: on the day of summer solstice, on which geographic la...
Open questionUSAAAO — 2018 First Round
Question 7
For the following problem, find the range in which the answer lies: looking from Greenwich on February 10th (s₀ = 9h17m4...
Open questionUSAAAO — 2018 First Round
Question 8
What is the main energy transport process in the core of the Sun?
Open questionUSAAAO — 2018 First Round
Question 9
What are the bright regions on the solar photosphere called?
Open questionUSAAAO — 2018 First Round
Question 10
When seen from Earth, what is Venus’ phase when it is at greatest elongation?
Open questionUSAAAO — 2018 First Round
Question 11
Which planets have primary atmospheres?
Open questionUSAAAO — 2018 First Round
Question 12
Which of the following planets or dwarf planets has not been visited by a spacecraft?
Open questionUSAAAO — 2018 First Round
Question 13
Star A has a surface temperature of 10,000 K while Star B has a surface temperature of 4,000 K. Star B is 10 times large...
Open questionUSAAAO — 2018 First Round
Question 14
What property of the interiors of stars changes at the Kraft break, around 1.6 Solar masses?
Open questionUSAAAO — 2018 First Round
Question 15
Which of the following stages will our Sun not evolve through?
Open questionUSAAAO — 2018 First Round
Question 16
Which of the following are not high mass stars (relative to the others)?
Open questionUSAAAO — 2018 First Round
Question 17
On a Hertzsprung-Russell diagram, where would we find stars that are cool and dim?
Open questionUSAAAO — 2018 First Round
Question 18
What do the cores of low-mass and high-mass main-sequence stars have in common?
Open questionUSAAAO — 2018 First Round
Question 19
The thermal pressure of a gas depends on
Open questionUSAAAO — 2018 First Round
Question 20
What happens to the core of a star after a planetary nebula occurs?
Open questionUSAAAO — 2018 First Round
Question 21
Find the visual magnitude of the binary star α Piscium, given that the visual magnitudes of each component in the binary...
Open questionUSAAAO — 2018 First Round
Question 22
Which of the following is not a method used to detect exoplanets?
Open questionUSAAAO — 2018 First Round
Question 23
Which of the following type of planet was the first to be discovered around a Solar-type star?
Open questionUSAAAO — 2018 First Round
Question 24
A star of radius 0.72 solar radii experiences a periodic dip in brightness once every 13.8 days, thought to be a result...
Open questionUSAAAO — 2018 First Round
Question 25
The center of the Milky Way is a part of which zodiac constellation?
Open questionUSAAAO — 2018 First Round
Question 26
The youngest stars in the Milky Way are found predominantly in which part of the galaxy?
Open questionUSAAAO — 2018 First Round
Question 27
In the 1920s Harlow Shapely estimated the size of the Milky Way galaxy using which of the following?
Open questionUSAAAO — 2018 First Round
Question 28
What is the theoretical diffraction limited angular resolution in visible light (5,500 Å) of a typical 20-cm (8 in) amat...
Open questionUSAAAO — 2018 First Round
Question 29
To improve the angular resolution of a telescope one must
Open questionUSAAAO — 2018 First Round
Question 30
Find the total sum of the binary system of the star Capella, if semi-major axis between them is 0.85 AU, and period of 0...
Open questionUSAAAO — 2019 First Round
Question 1
Which of the following relates the intrinsic luminosity of a spiral galaxy with its asymptotic rotation velocity?
Open questionUSAAAO — 2019 First Round
Question 2
Which of the following correctly gives the location of Population I vs. Population II stars in the Milky Way?
Open questionUSAAAO — 2019 First Round
Questions 3–4
A quasar with a bolometric flux of approximately 10⁻¹² erg s⁻¹ cm⁻² is observed at a redshift of 1.5, i.e. its comoving...
Open questionUSAAAO — 2019 First Round
Question 5
An observer is standing atop the Burj Khalifa, the tallest building on Earth (height = 830 m, latitude = 25.2 N, longitu...
Open questionUSAAAO — 2019 First Round
Question 6
Which of the following is closest to the ratio of the farthest distance to the horizon that can be seen by an observer s...
Open questionUSAAAO — 2019 First Round
Question 7
An observer measures the blackbody spectrum for a variety of bodies as a function of temperature and wavelength in the l...
Open questionUSAAAO — 2019 First Round
Question 8
Suppose a spacecraft were orbiting in a low Earth orbit at an altitude of 400 km. The spacecraft makes a single orbital...
Open questionUSAAAO — 2019 First Round
Question 9
After entering Mars orbit, a spacecraft finds that over the course of the Martian year, the position of Star A varies by...
Open questionUSAAAO — 2019 First Round
Question 10
Star A, of mass 3.5 M☉, shows radial-velocity variations 24.2 m/s in amplitude and 23.22 years in period, suggesting the...
Open questionUSAAAO — 2019 First Round
Question 11
Whether or not a diffraction-limited optical system can resolve two points as distinct can be determined by the Rayleigh...
Open questionUSAAAO — 2019 First Round
Question 12
The celestial coordinates of the Orion Nebula are RA 05h35m, dec −05°23′. Which of the following is closest to the time...
Open questionUSAAAO — 2019 First Round
Question 13
A yellow hypergiant located 1.04 kpc away has an apparent visual magnitude of 1.49 and a B − V color excess of 0.29. Ass...
Open questionUSAAAO — 2019 First Round
Question 14
The pp chain is a primary energy generation mechanism in the Sun. Each run of the process 2H + e → D + ν releases 26.73...
Open questionUSAAAO — 2019 First Round
Question 15
A relation between which of the following pairs of properties of Cepheid variables makes Cepheid variables, specifically...
Open questionUSAAAO — 2019 First Round
Question 16
Assuming that the Chandrasekhar Limit is 1.4 Solar masses, estimate the maximum average density (in kg/m³) of a Chandras...
Open questionUSAAAO — 2019 First Round
Question 17
The Sun’s differential rotation can be estimated with the equation ω = X + Y sin²(φ) + Z sin⁴(φ), where ω is angular vel...
Open questionUSAAAO — 2019 First Round
Question 18
An observer generates a light curve of a binary system and notices two different minima that repeat periodically in alte...
Open questionUSAAAO — 2019 First Round
Question 19
Eltanin, the brightest star in Draco, has approximate coordinates RA 17h56m, Dec +51.5°. Given that at the observer’s lo...
Open questionUSAAAO — 2019 First Round
Question 20
Stellar bodies located in the top left of a Hertzsprung-Russell diagram necessarily have which properties?
Open questionUSAAAO — 2019 First Round
Question 21
Which of the following correctly orders the following distance indicators from the smallest to largest scale?
Open questionUSAAAO — 2019 First Round
Question 22
As seen from Mars, what phase will Earth appear to be in when Mars is at quadrature from Earth?
Open questionUSAAAO — 2019 First Round
Question 23
Which of the following stars is almost always never visible to observers in the Northern hemisphere?
Open questionUSAAAO — 2019 First Round
Question 24
Two amateur astronomers A and B living in Ecuador are standing on the Equator at the Galapagos Islands (height 0 m, long...
Open questionUSAAAO — 2019 First Round
Question 25
The spectra of two stars A and B peak at wavelengths 500 nm and 250 nm respectively. What is the ratio of their luminosi...
Open questionUSAAAO — 2019 First Round
Question 26
Two stationary observers at a distance 100 AU from the Sun observe transits of Mercury across the diameter of the Sun’s...
Open questionUSAAAO — 2019 First Round
Question 27
Find the total sum of the binary system of the star Capella, if semi-major axis between them is 0.85 AU, and period of 0...
Open questionUSAAAO — 2019 First Round
Question 28
The New Horizons spacecraft completed a flyby of 2014 MU69 on New Year’s Day of this year. 2014 MU69 is a Kuiper Belt Ob...
Open questionUSAAAO — 2019 First Round
Question 29
HD 209458b is an extrasolar gas giant planet with a radius of 1.38 Jupiter radii and a mass of 0.69 Jupiter masses (1 Ju...
Open questionUSAAAO — 2019 First Round
Question 30
Imagine that our Sun was suddenly replaced by an M-dwarf with a mass half that of the Sun. If Earth kept the same semima...
Open questionUSAAAO — 2020 First Round
Question 1
The spectrum of a blackbody peaks at a wavelength inversely proportional to its temperature. This is known as Wein’s law...
Open questionUSAAAO — 2020 First Round
Question 2
Calculate the speed of the Sun around the center of mass due to the presence of Jupiter.
Open questionUSAAAO — 2020 First Round
Question 3
Hα is a prominent absorption line in the Sun’s spectrum with λ = 656.281 nm. For an observer on α-Centauri, assuming the...
Open questionUSAAAO — 2020 First Round
Question 4
Why does helium burn much faster than hydrogen in a star?
Open questionUSAAAO — 2020 First Round
Question 5
The Earth’s rotation axis happens to be pointing almost exactly at Polaris now, but Polaris will not always be the North...
Open questionUSAAAO — 2020 First Round
Question 6
A 13 kg telescope is mounted on a tripod such that the angle between tripod legs is 30°. How much is the force exerted o...
Open questionUSAAAO — 2020 First Round
Question 7
Capella, the brightest star in Auriga, has celestial coordinates 05h18m12.78s, +46°00′59.8″. At midnight local solar tim...
Open questionUSAAAO — 2020 First Round
Question 8
Kerbyn is a small rocky planet in a circular orbit around a 0.2 M☉ star with a semimajor axis of 0.1 AU. Kerbyn has an a...
Open questionUSAAAO — 2020 First Round
Question 9
Which of the following is responsible for the opacity of the Sun’s photosphere?
Open questionUSAAAO — 2020 First Round
Question 10
Planet Nine is a hypothetical planet in the outer Solar System, with a semimajor axis between 400 and 800 AU. Which of t...
Open questionUSAAAO — 2020 First Round
Question 11
The main reason why Io is volcanically active is due to:
Open questionUSAAAO — 2020 First Round
Question 12
Knowing that the distance between the Sun and Uranus is 2.87 × 10⁹ km and Uranus’ rotation period is 17h 14 min, determi...
Open questionUSAAAO — 2020 First Round
Question 13
The angular diameter of star A with apparent bolometric magnitude 2 is 2.5 times greater than the angular diameter of st...
Open questionUSAAAO — 2020 First Round
Question 14
As a consequence of the virial theorem, how does the stellar temperature (T) change if we add more arbitrary energy (E)...
Open questionUSAAAO — 2020 First Round
Question 15
How do we increase the reaction time for hydrogen fusion at the stellar core leaving other factors unchanged?
Open questionUSAAAO — 2020 First Round
Question 18
Recently, the exoplanet Proxima Centauri b was discovered using the radial-velocity method. Its orbital period is 11.19...
Open questionUSAAAO — 2020 First Round
Question 19
Proxima Centauri b has an orbital period of 11.19 days and orbits Proxima Centauri, which has a mass of 0.122 Solar mass...
Open questionUSAAAO — 2020 First Round
Question 20
A star cluster with a main-sequence turn-off at around 6000 K effective temperature is about:
Open questionUSAAAO — 2020 First Round
Question 21
The 21 cm absorption line is a tracer for what kind of gas?
Open questionUSAAAO — 2020 First Round
Question 22
From the shortest distances to the longest, what is the correct order of distance determination techniques?
Open questionUSAAAO — 2020 First Round
Question 23
In a particular compact binary system consisting of a black hole and a main sequence star, the black hole has a mass of...
Open questionUSAAAO — 2020 First Round
Question 25
The Hα line (λ₀ = 656.28 nm) of a galaxy is observed to be redshifted to λ = 814.35 nm. Assuming only cosmological redsh...
Open questionUSAAAO — 2020 First Round
Question 26
At what redshift would the average temperature in the universe have been hot enough to emit 1 nm photons? The current CM...
Open questionUSAAAO — 2020 First Round
Question 27
In April, the Event Horizon Telescope released the first image of the supermassive black hole of M87. The black hole has...
Open questionUSAAAO — 2020 First Round
Question 28
At optical wavelengths, star formation is strongly obscured by dust. Studies of protoplanetary disks therefore usually o...
Open questionUSAAAO — 2020 First Round
Question 29
A very curious astronomer decided to cover the left half of the objective lens of a telescope with opaque material. If h...
Open questionUSAAAO — 2021 First Round
Question 1
On December 21, 2020, Jupiter was at (α, δ) = (20h 10m, −20° 34′). Which constellation was Saturn in?
Open questionUSAAAO — 2021 First Round
Question 2
What is the spectral type of a star with a luminosity of 5.86 × 10^26 W and radius of 8.51 × 10^8 m?
Open questionUSAAAO — 2021 First Round
Question 3
The exoplanet HD 209458b has a mass of 0.71 Jupiter masses and orbits HD 209458 with an orbital period of 3.53 days. HD...
Open questionUSAAAO — 2021 First Round
Question 4
The photon number density of a blackbody depends on temperature as n_d = a (k_B T / ħc)^n, where k_B is the Boltzmann co...
Open questionUSAAAO — 2021 First Round
Question 5
HD 209458b has a radius of 1.35 Jupiter radii, while the radius of HD 209458 is 1.20 Solar radii. What is the transit de...
Open questionUSAAAO — 2021 First Round
Question 6
Which of the following is a problem of the conventional Big Bang theory that is resolved by the theory of inflation?
Open questionUSAAAO — 2021 First Round
Question 7
Comet C/2020 F3 (NEOWISE) last reached perihelion on July 3, 2020. Comet NEOWISE has an orbital period of ≈ 4400 years a...
Open questionUSAAAO — 2021 First Round
Question 8
An astronomer detected a galaxy and decided to analyze its different parts and physical aspects. The frequency generated...
Open questionUSAAAO — 2021 First Round
Question 9
A stable open cluster of about N = 1000 Sun-like stars has an angular diameter of θ = 60 arcminutes and distance d = 500...
Open questionUSAAAO — 2021 First Round
Question 10
What would happen to the analemma of the Sun if the obliquity of the Earth's orbit suddenly went to zero degrees and its...
Open questionUSAAAO — 2021 First Round
Question 11
Let Td,C and Td,S be the temperatures at the core and the surface of the sun, respectively. Similarly, let TA,C and TA,S...
Open questionUSAAAO — 2021 First Round
Question 12
The spectral line Hα in the spectrum of a star is recorded as having displacement of ∆λ = 0.043 × 10^-10 m. At rest, the...
Open questionUSAAAO — 2021 First Round
Question 13
The reflector telescope built by Sir Issac Newton was a f/5 telescope and had a primary mirror of diameter 30mm. He used...
Open questionUSAAAO — 2021 First Round
Question 14
Take a look at the following image: Three Messier objects are circled in the image. Select the alternative that correctl...
Open questionUSAAAO — 2021 First Round
Question 15
An interesting phenomena that happens in the Solar System is the capture of comets in the interstellar medium. Assume th...
Open questionUSAAAO — 2021 First Round
Question 16
In a certain day, when it is 0h UT, the sidereal time of Prime Meridian is 5h 56min 9.4s. For this day, with start and e...
Open questionUSAAAO — 2021 First Round
Question 17
Consider the following horrifying scenario. The Sun has become a Red Giant, and its radius is doubling every 100 years....
Open questionUSAAAO — 2021 First Round
Question 18
TESS Object of Interest (TOI) 402.01 has an orbital period of 4.756 ± 0.000023 (days) and was last observed to transit o...
Open questionUSAAAO — 2021 First Round
Question 19
Jupiter has a mass of 1.90 × 10^27 kg and a radius of 7.15 × 10^7 m. To the closest order of magnitude, estimate the pre...
Open questionUSAAAO — 2021 First Round
Question 20
Which of the following statements is wrong?
Open questionUSAAAO — 2021 First Round
Question 21
Consider a horizontal sundial where the triangular gnomon rises at an angle equal to the sundial site's latitude, φ = 38...
Open questionUSAAAO — 2021 First Round
Question 22
Consider an eclipsing binary star system observed (in some fixed band) to have a combined apparent magnitude of 5.67. Du...
Open questionUSAAAO — 2021 First Round
Question 23
An astronomer observes that a Solar type star has an apparent V magnitude of 6.73 when seen from the Earth. Assuming tha...
Open questionUSAAAO — 2021 First Round
Question 24
1. The temperature of the Sun is 5000K while that of Sirius is 10000K. Which star has a higher integrated radiance i.e....
Open questionUSAAAO — 2021 First Round
Question 25
Suppose a spaceship is attempting a slingshot maneuver on a gas giant with mass 100 times that of the spaceship. Because...
Open questionUSAAAO — 2021 First Round
Question 26
Let's imagine that our Universe would be filled with basketballs, each having a mass of mb = 0.62 kg. What would be the...
Open questionUSAAAO — 2021 First Round
Question 28
An often-repeated fun fact is that humans produce more power per unit volume than stars. If the sun were the same size,...
Open questionUSAAAO — 2021 First Round
Question 29
Given that the redshift of cosmic microwave background (CMB) is 1100, what was the temperature of the Universe when phot...
Open questionUSAAAO — 2021 First Round
Question 30
Where and when should we place a radio telescope such that, when combined with a radio telescope on Earth, the system co...
Open questionUSAAAO — 2022 First Round
Question 1
Classify the following galaxies according the Hubble galaxies classification: Figure 1: Galaxy 1 Figure 2: Galaxy 2 Figu...
Open questionUSAAAO — 2022 First Round
Question 2
A comet’s orbit has the following characteristics: eccentricity e = 0.995; aphelion distance r_a = 5 × 10^4 AU. Assume w...
Open questionUSAAAO — 2022 First Round
Question 3
Consider the following elliptical orbit of a comet around a star: Which of the following expressions corresponds to the...
Open questionUSAAAO — 2022 First Round
Question 4
What is the shortest distance (along the surface of the Earth) between two points on the Equator separated by 30° of lon...
Open questionUSAAAO — 2022 First Round
Question 5
Two (spherical) asteroids, Ek and Do, are orbiting in free space around their stationary center of mass. Ek has mass 7M_...
Open questionUSAAAO — 2022 First Round
Question 6
Consider a f/9 telescope with focal length f = 1.0 m that operates at visible wavelength λ = 5000 Å. What is the farthes...
Open questionUSAAAO — 2022 First Round
Question 7
Imagine the you observe transits of earth across the sun from a far away exoplanet. Assuming earth's orbit has 0 eccentr...
Open questionUSAAAO — 2022 First Round
Question 8
An exoplanet was observed during its transit across the surface of a bright star. Estimate the variation of the apparent...
Open questionUSAAAO — 2022 First Round
Question 9
Estimate the mass of a globular cluster with a radial velocity dispersion σ_r = 16.2 km/s. The cluster has an angular di...
Open questionUSAAAO — 2022 First Round
Question 10
Jupiter's deep atmosphere is very warm due to convection leading to an adiabatic temperature profile that increases with...
Open questionUSAAAO — 2022 First Round
Question 11
An astronomer took the following picture while observing the night sky: What is the latitude of the place where the astr...
Open questionUSAAAO — 2022 First Round
Question 12
Order the following phases of the Sun's evolution from first to last chronologically. 1. Helium flash 2. White dwarf 3....
Open questionUSAAAO — 2022 First Round
Question 13
The orbit of some planet to its star has an eccentricity of 0.086. What is the ratio of the planet's closest distance to...
Open questionUSAAAO — 2022 First Round
Question 14
Figure 6 shows a 6-hr root-mean-square (rms) Combined Differential Photometric Precision (CDPP) curve for 150,000 stars...
Open questionUSAAAO — 2022 First Round
Question 15
A star with mass M goes through an energy-generating nuclear reaction 4 ¹H → ⁴He + Energy. Here, the burning efficiency...
Open questionUSAAAO — 2022 First Round
Question 16
In 2025, the Parker Solar Probe will pass just 6.9 × 10^6 km from the Sun, becoming the closest man-made object to the S...
Open questionUSAAAO — 2022 First Round
Question 17
An astronomer observes an eclipsing binary star system from Earth, and he plots the following light curve. Suppose that...
Open questionUSAAAO — 2022 First Round
Question 18
Assume that the smaller star in the binary star system shown below is brighter than the larger star. What is the ratio o...
Open questionUSAAAO — 2022 First Round
Question 19
The resolution of a space telescope is theoretically limited by diffraction from its primary mirror. In this problem, we...
Open questionUSAAAO — 2022 First Round
Question 20
The eccentricity of Pluto's orbit is 0.25. Estimate the maximum change in magnitude of Pluto as seen from Earth in one o...
Open questionUSAAAO — 2022 First Round
Questions 21–22
A satellite is in a circular, equatorial orbit, and can fire its engines to accelerate in any of the following direction...
Open questionUSAAAO — 2022 First Round
Question 23
An exoplanet discovered by the radial velocity method is found to have an orbital period of 2.45 days around a Sun-like...
Open questionUSAAAO — 2022 First Round
Question 24
Deneb is a very important star in the Northern hemisphere as it is one of the three stars in the Summer Triangle. Deneb...
Open questionUSAAAO — 2022 First Round
Question 25
Suppose you are in Houston (29°461N 95°231W) on the fall equinox and you just observed Deneb culminating (upper culminat...
Open questionUSAAAO — 2022 First Round
Question 26
Knowing that the following image was taken at 11:59pm, determine the name of which constellation was the sun passing in...
Open questionUSAAAO — 2022 First Round
Question 27
An astronomer observes a galaxy in very foggy weather. So far, she has an image of signal-to- noise ratio of approximate...
Open questionUSAAAO — 2022 First Round
Question 28
Dubhe (declination δ = 61.75 °) is a star in the constellation of Ursa Major. Is it circumpolar from the city of San Fra...
Open questionUSAAAO — 2022 First Round
Question 29
An astronomer takes a spectrum of a galaxy and observes that the hydrogen-alpha emission line is at a wavelength of 721....
Open questionUSAAAO — 2022 First Round
Question 30
What is the time difference between the longest day of the year and the shortest day of the year in San Francisco (37.7°...
Open questionUSAAAO — 2023 First Round
Question 1
According to the astronomical Julian day count, JD 2459946.0 corresponds to January 1, 2023 at 12:00 UT. What would be t...
Open questionUSAAAO — 2023 First Round
Question 2
A cluster has a radius of 2 parsecs. A Sun-like star in the cluster has an apparent magnitude of 10. When we look at the...
Open questionUSAAAO — 2023 First Round
Question 3
The radius of the Moon is about 4 times smaller than the radius of the Earth. The mean albedos of the Moon and the Earth...
Open questionUSAAAO — 2023 First Round
Question 4
The Sun has a surface temperature of about 6000 K and its blackbody emission peaks in the visible spectrum. Around 1940s...
Open questionUSAAAO — 2023 First Round
Question 5
Friedrich Bessel was the first person to quantitatively measure the annual change in stellar positions due to the motion...
Open questionUSAAAO — 2023 First Round
Question 6
Compute the blackbody luminosity of a neutron star with its surface temperature at 10^6 K and radius 10^4 m.
Open questionUSAAAO — 2023 First Round
Question 7
Fill in the blanks. The Balmer lines are a series of emission spectrum of hydrogen. In the low temperature interstellar...
Open questionUSAAAO — 2023 First Round
Question 8
A comet passes near the Sun on a parabolic orbit. While it's passing near the Sun with orbital velocity V , the Sun's he...
Open questionUSAAAO — 2023 First Round
Question 9
Consider Galaxies A and B, both of which have radius R. At a distance R from its center, Galaxy A's rotational velocity...
Open questionUSAAAO — 2023 First Round
Question 10
Consider a satellite that has a circular orbit with a radius of 6.0 × 10^8 m around Venus. Due to a failure in its ignit...
Open questionUSAAAO — 2023 First Round
Question 11
Consider a main-sequence star with mass M = 9.1 × 10^29 kg, which is sustained through the proton-proton chain reaction,...
Open questionUSAAAO — 2023 First Round
Question 12
A planet is in an elliptical orbit around a star. Let rmin be the minimum distance between the planet and star, and let...
Open questionUSAAAO — 2023 First Round
Question 13
The apparent magnitude of a star of radius 0.41R☉ as observed from Earth appears to fluctuate by 0.037. That is, the dif...
Open questionUSAAAO — 2023 First Round
Question 14
An empirically determined approximate formula for the lifetime of a star is given by: T = (M☉ / M)^2.5 × 10^10 years, wh...
Open questionUSAAAO — 2023 First Round
Question 15
With the technology currently available, it would take hundreds of millennia to send a human-made object to other stars....
Open questionUSAAAO — 2023 First Round
Question 16
Which of the following constellations is not on the sky map below?
Open questionUSAAAO — 2023 First Round
Questions 17–18
The fictional towns of Baia and Caia are located at (66.56° N, 67.55° E) and (δ, 18.95° E), respectively. It is known th...
Open questionUSAAAO — 2023 First Round
Question 19
In 1995, researchers at the University of Geneva discovered an exoplanet in the main-sequence star 51 Pegasi. This was t...
Open questionUSAAAO — 2023 First Round
Question 20
Suppose that an astronomer detects an electromagnetic wave of frequency ν. Some time later, another wave with the same a...
Open questionUSAAAO — 2023 First Round
Question 21
Consider the binary system Kepler-16, which has the primary star Kepler-16A and the secondary star Kepler-16B. It has an...
Open questionUSAAAO — 2023 First Round
Question 22
The habitable zone of a star is defined as the one where water in the liquid state can exist in the surface of a planet....
Open questionUSAAAO — 2023 First Round
Question 23
Billions of years from now, as the Moon moves farther away from the Earth, the Earth's axial tilt may become unstable. I...
Open questionUSAAAO — 2023 First Round
Question 24
Erez is designing a Newtonian telescope! The equation of the primary mirror is y = x^2/(36 m) − 1 m, and the telescope t...
Open questionUSAAAO — 2023 First Round
Question 25
Consider a hypothetical planet orbiting the Sun with an obliquity angle i (angle between the axis of rotation and the no...
Open questionUSAAAO — 2023 First Round
Question 26
A comet is approaching our solar system from the depths of space with a velocity of 10000 m/s, and if it continues movin...
Open questionUSAAAO — 2023 First Round
Question 27
How far from the Solar System would a galaxy with a redshift of 0.035 be?
Open questionUSAAAO — 2023 First Round
Question 28
Two planets A and B orbit a star with coplanar orbital paths that don't intersect. The major axes of the orbits are perf...
Open questionUSAAAO — 2023 First Round
Question 29
Here is a map of MIT and the surrounding area, where North points directly upwards, as taken from https://whereis.mit.ed...
Open questionUSAAAO — 2023 First Round
Question 30
After a day spent showing a visiting friend around Boston, Leo is walking back along the bridge (see diagram below) to r...
Open questionUSAAAO — 2024 First Round
Question 1
David is walking down MIT’s infinite corridor (latitude 42°21′33″) when he suddenly sees the sun aligning with the windo...
Open questionUSAAAO — 2024 First Round
Question 2
Abhay looks at the light curves for two main sequence stars A and B, which you can assume are blackbodies. A has its pea...
Open questionUSAAAO — 2024 First Round
Question 3
Aliens in a nearby star system (located in a random direction from Earth) are looking for nearby planets using the trans...
Open questionUSAAAO — 2024 First Round
Question 4
Orion is observing the sky with two telescopes that he just made. Orion wrote down that the first telescope has a primar...
Open questionUSAAAO — 2024 First Round
Question 5
A supernova is triggered largely by neutrinos. In fact, 99% of the energy coming from the supernova is released in form...
Open questionUSAAAO — 2024 First Round
Question 6
Newly discovered planets DDP and CJ are found to orbit a nearby star, as shown in the figure below. Planet CJ has a circ...
Open questionUSAAAO — 2024 First Round
Question 7
Arjun launches a 50 kg rocket with speed 10,405 m/s from the surface of the Earth and redirects it into a stable ellipti...
Open questionUSAAAO — 2024 First Round
Question 8
The mass density of the Milky Way galaxy determines the orbital velocity of planets, stars, and other objects orbiting a...
Open questionUSAAAO — 2024 First Round
Question 9
Let’s assume that on an expedition mission to Mars, we take a telescope with 0.01 arcsecond angular resolution from eart...
Open questionUSAAAO — 2024 First Round
Question 10
Ben Chen is an alien living on a system identical to earth, except his planet’s obliquity is 0°. Located at latitude 42....
Open questionUSAAAO — 2024 First Round
Questions 11–12
Joe lives at the bottom of a vertical cylindrical hole with a radius of 10 m at a depth of 10 km below the surface. He s...
Open questionUSAAAO — 2024 First Round
Question 13
Samvit observes a binary star system of masses M1 and M2. Unfortunately, the star with mass M2 is too dim for him to obs...
Open questionUSAAAO — 2024 First Round
Question 14
The surface of the Sun exhibits differential rotation, with different rotational periods at different latitudes. We can...
Open questionUSAAAO — 2024 First Round
Question 15
Two protons A and B lie in the solar interior. In the rest frame of proton A, the proton B approaches it radially from a...
Open questionUSAAAO — 2024 First Round
Question 16
Consider a sun-planet-moon system. The rotation period of the planet is 2 days. The period of revolution of the moon aro...
Open questionUSAAAO — 2024 First Round
Question 17
The Extremely Large Telescope (ELT) is an optical telescope under construction in Chile. The primary mirror has been pla...
Open questionUSAAAO — 2024 First Round
Questions 18–19
At 6am on March 20th, as the Sun is rising, Leo, who is at (40° N, 75° W), plants a stick vertically on the ground. At t...
Open questionUSAAAO — 2024 First Round
Question 20
Imagine a very long cylindrical planet that has a satellite orbiting around it. Considering that the average density of...
Open questionUSAAAO — 2024 First Round
Question 21
The problem of magnetic monopoles — that is, the apparent absence of magnetic monopoles in the universe — arises from th...
Open questionUSAAAO — 2024 First Round
Question 22
Tara is investigating a new interesting type of stars she decides to call the X stars. She observes that in an X star of...
Open questionUSAAAO — 2024 First Round
Question 24
Tara has become obsessed with X stars and decides to look for them in other galaxies. She observes one on the edge of a...
Open questionUSAAAO — 2024 First Round
Question 25
There is a galaxy at redshift 0.5 for which we have a measurement for apparent bolometric magnitude to be 22. With a sta...
Open questionUSAAAO — 2024 First Round
Question 26
An astronomer wants to design a telescope so that the full moon fills the entire FOV of the telescope. She uses an eyepi...
Open questionUSAAAO — 2024 First Round
Question 27
The Cosmic Microwave Background is made of light that was released when the Universe first became transparent. It is a b...
Open questionUSAAAO — 2024 First Round
Question 28
Moving into MIT for the start of the spring semester, Austin is flying from Lubbock, Texas (33.58° N, 101.84° W) to Bost...
Open questionUSAAAO — 2024 First Round
Question 29
After that slight headache, Austin is back at MIT in Boston! For his astronomy research, he is observing the LARES satel...
Open questionUSAAAO — 2025 First Round
Question 1
Imagine you are on Deimos right now and you want to escape Mars because you are bored. If Deimos is currently at 23,460...
Open questionUSAAAO — 2025 First Round
Questions 2–3
Suppose a spherical gas giant has radius R, temperature T, uniform density and composition, and fixed volumetric heat ca...
Open questionUSAAAO — 2025 First Round
Question 4
Suppose a rocket around a star of mass M wishes to execute an orbital transfer from a circular orbit with radius R to a...
Open questionUSAAAO — 2025 First Round
Question 5
It may be useful to know the semi-latus rectum of an ellipse is the distance between one of its foci and the point on th...
Open questionUSAAAO — 2025 First Round
Question 6
Galileo the Tyrant has conquered the Earth. In his madness, he launched many bright satellites into space because he tho...
Open questionUSAAAO — 2025 First Round
Question 7
What is the geodesic distance between Boston (42°21′37″ N, 71°3′28″ W) and Mumbai (19°4′34″ N, 72°52′39″ E)? Assume that...
Open questionUSAAAO — 2025 First Round
Question 8
Which of the following statements are correct regarding spectral broadening? P: In the limit of zero temperature, spectr...
Open questionUSAAAO — 2025 First Round
Question 9
Which of the following statements are true about a cluster of main sequence stars: A: For two star clusters of the same...
Open questionUSAAAO — 2025 First Round
Question 10
Match each imaginary line in the sky map below to its label.
Open questionUSAAAO — 2025 First Round
Questions 11–12
An astronomer was studying the exoplanets orbiting a star with a mass of 10 M☉. The astronomer decided to draw a log T v...
Open questionUSAAAO — 2025 First Round
Question 13
A recently observed exosolar system consists of a star, a planet, and the planet’s satellite. The satellite has a revolu...
Open questionUSAAAO — 2025 First Round
Question 14
A cylindrical space station rotating about its primary axis could create artificial “spin gravity,” allowing people to l...
Open questionUSAAAO — 2025 First Round
Question 15
A cylindrical space station rotating about its primary axis could create artificial “spin gravity,” allowing people to l...
Open questionUSAAAO — 2025 First Round
Question 16
A cylindrical space station rotating about its primary axis could create artificial “spin gravity,” allowing people to l...
Open questionUSAAAO — 2025 First Round
Question 17
Consider a giant star with radius R. The core has temperature Tc and the surface has temperature Ts ≪ Tc. Given R, Tc, a...
Open questionUSAAAO — 2025 First Round
Question 18
Connor is stranded on an island and wishes to determine his latitude, but he only wakes up at sunrise and sunset. He con...
Open questionUSAAAO — 2025 First Round
Question 19
Which of the following statements CANNOT be inferred from Kepler’s laws of motion? I: A planet moves in an elliptical or...
Open questionUSAAAO — 2025 First Round
Question 20
Just before dawn of the summer solstice, Christopher the sailor begins sailing due West from 50° N, 5° W. His watch is s...
Open questionUSAAAO — 2025 First Round
Question 21
What is the largest range of latitudes φ for which, at some time during the day, the line between Rigel (αR = 5h 14m 32s...
Open questionUSAAAO — 2025 First Round
Question 22
Observed from the equator, what is the maximum duration over which Venus can be observed (continuously) after sunset? As...
Open questionUSAAAO — 2025 First Round
Question 23
The Earth orbits the Sun with orbital eccentricity e = 0.0167. What percent more total solar irradiance does the Earth r...
Open questionUSAAAO — 2025 First Round
Question 24
Consider a main sequence star 500 times less luminous than the sun. This star must have a ______ core and a ______ envel...
Open questionUSAAAO — 2025 First Round
Question 25
Evan uses a telescope of focal distance f = 1000 mm to observe a star known to have a parallax p = 50 mas. Observing the...
Open questionUSAAAO — 2025 First Round
Question 26
Two exoplanets, A and B, have circular orbits around the same central star. Suppose that the ascending nodes of the orbi...
Open questionUSAAAO — 2025 First Round
Question 27
Cosmologists consider three possible universes: universes dominated by baryonic matter (i.e. ordinary matter), universes...
Open questionUSAAAO — 2025 First Round
Question 28
Suppose leap days were removed from the calendar, so that each calendar year has exactly 365 days. In the first year of...
Open questionUSAAAO — 2025 First Round
Question 29
It is observed that a planet orbiting a star increases the observed magnitude of the system by 0.005 when it transits ac...
Open questionUSAAAO — 2025 First Round
Question 30
What is the focal ratio of a telescope with 1.2 m in focal length and 12 cm in aperture?
Open questionUSAAAO — 2026 First Round
Question 1
A planet moves in a circular orbit in a fixed plane with angular velocity ω, and let n-hat be a unit vector perpendicula...
Open questionUSAAAO — 2026 First Round
Question 2
A planet of mass m orbits a star of mass M in an elliptical orbit with semi-major axis a and eccentricity e where M ≫ m....
Open questionUSAAAO — 2026 First Round
Question 3
Astronomers in the United States observe a spiral galaxy and measure its rotation curve. They find that beyond a radius...
Open questionUSAAAO — 2026 First Round
Question 4
You are stranded on a remote island somewhere on Earth, at an unknown date and time (in the 21st century). You look up a...
Open questionUSAAAO — 2026 First Round
Question 5
You are stranded on a remote island somewhere on Earth, at an unknown date and time (in the 21st century). You look up a...
Open questionUSAAAO — 2026 First Round
Question 6
You are stranded on a remote island somewhere on Earth, at an unknown date and time (in the 21st century). You look up a...
Open questionUSAAAO — 2026 First Round
Questions 7–8
One of Stephen Hawking’s most famous predictions was the existence of Hawking radiation. Specifically, black holes act l...
Open questionUSAAAO — 2026 First Round
Question 9
The asteroid Pallas orbits the Sun with a semi-major axis of 2.77 AU. What is its orbital period around the Sun in years...
Open questionUSAAAO — 2026 First Round
Question 10
A small satellite orbits the Earth so it stays directly above a fixed point on the equator. Using 5.97 × 10²⁴ kg for Ear...
Open questionUSAAAO — 2026 First Round
Question 11
Four bright stars were erased from the sky map below. All of these stars have magnitudes lower than 3.0. Select the alte...
Open questionUSAAAO — 2026 First Round
Question 12
An extraterrestrial form of life from a distant planetary system observed a transit of Jupiter across the Sun. The trans...
Open questionUSAAAO — 2026 First Round
Question 13
What is the smallest angular separation between Algol (β Per) and the Sun throughout the year? Algol’s declination is +4...
Open questionUSAAAO — 2026 First Round
Question 14
Consider a cloud of hot gas with radius R and total (electromagnetic) power emission rate P. Keeping the average tempera...
Open questionUSAAAO — 2026 First Round
Question 15
Lunar laser ranging experiments show that, due to tidal effects, the semi-major axis of the Moon’s orbit increases by ar...
Open questionUSAAAO — 2026 First Round
Question 16
Kepler-22b is an exoplanet discovered by transiting with an orbital period of 290 days. Suppose it has a mass of 4.84 ×...
Open questionUSAAAO — 2026 First Round
Question 17
A quickly-moving black hole passes through the center of a large star cluster. While the black hole does not experience...
Open questionUSAAAO — 2026 First Round
Question 18
The most distant known galaxy, MoM-z14, was recently observed by the James Webb Space Telescope and has a redshift of z...
Open questionUSAAAO — 2026 First Round
Question 19
Assume a spherical star has a density profile described by the equation ρ(r) = (1 − r³/R³) ρc, for 0 ≤ r ≤ R. Find ρc in...
Open questionUSAAAO — 2026 First Round
Question 20
Some stars formed in the early universe are still observable today. If an observer observed one and it is still in the m...
Open questionUSAAAO — 2026 First Round
Question 21
Consider the following graph (below), which shows the mean orbital velocity of stars around a galaxy’s center as a funct...
Open questionUSAAAO — 2026 First Round
Question 22
Consider the following graph (below), which shows the mean orbital velocity of stars around a galaxy’s center as a funct...
Open questionUSAAAO — 2026 First Round
Question 23
Consider the following graph (below), which shows the mean orbital velocity of stars around a galaxy’s center as a funct...
Open questionUSAAAO — 2026 First Round
Question 24
Suppose the Honeyhive galaxy and the Gold Leaf galaxy are diametrically opposite when viewed from the Earth, and the fol...
Open questionUSAAAO — 2026 First Round
Question 25
The Balmer-α, H-I, and Lyman-α lines are important spectral lines in astronomy, all from hydrogen. The Balmer-α line occ...
Open questionUSAAAO — 2026 First Round
Question 26
Star X and star Y form an eclipsing binary system, where star X is larger, and fully blocks star Y during an eclipse. Du...
Open questionUSAAAO — 2026 First Round
Question 27
When plotting the distribution of asteroids in the asteroid belt by their semi-major axis, we can see several regions, k...
Open questionUSAAAO — 2026 First Round
Question 28
Below is an HR diagram for a globular cluster from Gaia DR3 data. The figure has labeled regions: “A”, “B”, “C”, and “D”...
Open questionUSAAAO — 2026 First Round
Question 29
Which of the following is closest to the ratio of the number of photons from the Sun that strike the Earth each second t...
Open questionUSAAAO — 2026 First Round
Question 30
Consider two galaxies: Galaxy S is a spiral galaxy with blue spiral arms. Galaxy E is an elliptical galaxy with no blue...
Open questionIAAC — 2019 Final Round
Question 1
Most people use °C (degree Celsius) to measure everyday temperatures. Astronomers prefer to use K (Kelvin) to measure te...
Open questionIAAC — 2019 Final Round
Question 2
Mars might be a place for future human explorations. However, humans cannot breathe on the surface of Mars because the a...
Open questionIAAC — 2019 Final Round
Question 3
The two moons of Mars are called ...
Open questionIAAC — 2019 Final Round
Question 4
On which planet in our solar system can you find the Great Red Spot?
Open questionIAAC — 2019 Final Round
Question 5
The axis of the Earth is tilted at an angle of approximately ... relative to the orbital plane around the Sun.
Open questionIAAC — 2019 Final Round
Question 6
The Pleiades is an open star cluster that plays a role in many ancient stories and is well-known for containing ... brig...
Open questionIAAC — 2019 Final Round
Question 7
Previous IAAC rounds featured Proxima/Alpha Centauri as closest star(system) to the Earth. Which one is the second close...
Open questionIAAC — 2019 Final Round
Question 8
The visible part of the electromagnetic spectrum is between ...
Open questionIAAC — 2019 Final Round
Question 9
The constellation ... is a bright W-shaped constellation in the northern sky.
Open questionIAAC — 2019 Final Round
Question 10
What is the so-called bolometric luminosity in astronomy?
Open questionIAAC — 2019 Final Round
Question 11
The second cosmic velocity (or escape velocity) is the speed required by an object to escape the gravitational field of...
Open questionIAAC — 2019 Final Round
Question 12
The International Space Station (ISS) circles the Earth approximately 410 km above the ground. Find the best estimate fo...
Open questionIAAC — 2019 Final Round
Question 13
Find the best approximation for the surface temperature of the Sun:
Open questionIAAC — 2019 Final Round
Question 14
The four big moons of Jupiter are Callisto, Europa, Ganymede, and Io. Which one of them has the smallest distance to Jup...
Open questionIAAC — 2019 Final Round
Question 15
The name of the black hole in the center of our Milky Way is ...
Open questionIAAC — 2019 Final Round
Question 16
Approximately how far away is the Andromeda Galaxy?
Open questionIAAC — 2019 Final Round
Question 17
When was the telescope invented by Galileo?
Open questionIAAC — 2019 Final Round
Question 18
The astronomical unit parsec (pc) plays a crucial role in astronomy. One parsec is equal to about 3.26 light-years. How...
Open questionIAAC — 2019 Final Round
Question 19
The picture below shows a very famous nebula: What is the name of this nebula?
Open questionIAAC — 2019 Final Round
Question 20
The star Betelgeuse is one of the brightest stars in the night sky with remarkable red color. In which constellation is...
Open questionIAAC — 2019 Final Round
Question 21
What does the astronomical term ecliptic describe?
Open questionIAAC — 2019 Final Round
Question 22
Approximately how long does it take Pluto to orbit the Sun once?
Open questionIAAC — 2019 Final Round
Question 23
Sunspots are black regions that temporarily appear on the Sun. Their number highly increases every ... years. This perio...
Open questionIAAC — 2019 Final Round
Question 24
The Large Magellanic Cloud is ...
Open questionIAAC — 2019 Final Round
Question 25
The Milky Way is part of a giant supercluster with a diameter of 160 Mpc. What is the name of this supercluster?
Open questionIAAC — 2019 Final Round
Question 26
Why are Cepheid stars relevant for astronomers?
Open questionIAAC — 2019 Final Round
Question 27
What type of radiation causes a black hole to evaporate over time?
Open questionIAAC — 2019 Final Round
Question 28
In astronomy, the concept of black bodies is very important to better calculate the radiation of stars. Which one is the...
Open questionIAAC — 2019 Final Round
Question 29
One astronomical unit (AU) is equal to approximately ...
Open questionIAAC — 2019 Final Round
Question 30
Radio telescopes are crucial for astronomical observations. Which one of these well-known radio telescopes has the large...
Open questionIAAC — 2019 Final Round
Question 31
Which one of these constellations is not located along the Milky Way in the sky?
Open questionIAAC — 2019 Final Round
Question 32
A comet’s tail points in the following direction:
Open questionIAAC — 2019 Final Round
Question 33
As the life of a star progresses, heavy elements are produced. The elements form layers around the star in this order (s...
Open questionIAAC — 2019 Final Round
Question 34
The so-called dark energy is a model to explain ...
Open questionIAAC — 2019 Final Round
Question 35
As a star collapses at the end of its life, the triple-alpha reaction takes place. Which one of these equations describe...
Open questionIAAC — 2019 Final Round
Question 36
Besides large astronomical objects, astrophysicists are also interested in small particles from space. Which one of thes...
Open questionIAAC — 2019 Final Round
Question 37
The term Schwarzschild radius usually describes properties of ...
Open questionIAAC — 2019 Final Round
Question 38
What is the correct numerical value and unit of the Boltzmann constant?
Open questionIAAC — 2019 Final Round
Question 39
What is true for a type-Ia (“type one-a”) supernova?
Open questionIAAC — 2019 Final Round
Question 40
The famous Drake equation attempts to answer the following question:
Open questionIAAC — 2020 Final Round
Question 1
How many parsecs are approximately 23 light years?
Open questionIAAC — 2020 Final Round
Question 2
Which one is the biggest moon of Jupiter?
Open questionIAAC — 2020 Final Round
Question 3
Which object was investigated by the Cassini research mission?
Open questionIAAC — 2020 Final Round
Question 4
What is the distinctive color of the star Betelgeuse?
Open questionIAAC — 2020 Final Round
Question 5
The International Space Station circles the Earth approximately every ...
Open questionIAAC — 2020 Final Round
Question 6
The well-known Hyades star cluster is located in the constellation ...
Open questionIAAC — 2020 Final Round
Question 7
What is the diameter of the Sun approximately?
Open questionIAAC — 2020 Final Round
Question 8
The planet Jupiter orbits the Sun in ...
Open questionIAAC — 2020 Final Round
Question 9
The value of the Hubble constant is approximately ...
Open questionIAAC — 2020 Final Round
Question 10
The first gravitational wave GW150914 was detected by using a Michelson interferometer with an arm length of ...
Open questionIAAC — 2020 Final Round
Question 11
The Event Horizon Telescope is a very long baseline interferometry array observing at a wavelength of ...
Open questionIAAC — 2020 Final Round
Question 12
Light with a wavelength of 100 micrometres is called ...
Open questionIAAC — 2020 Final Round
Question 13
How high above the Earth’s equator is the geostationary orbit located?
Open questionIAAC — 2020 Final Round
Question 14
Voyager 1 is the most distant man-made object. How fast is Voyager 1 moving away from the Sun at the moment?
Open questionIAAC — 2020 Final Round
Question 15
When was the dwarf planet Pluto discovered?
Open questionIAAC — 2020 Final Round
Question 16
How many times more mass has the Earth compared to the Moon?
Open questionIAAC — 2020 Final Round
Question 17
What does the astronomical term barycentre describe?
Open questionIAAC — 2020 Final Round
Question 18
How many Lagrange points exist in a two-body system?
Open questionIAAC — 2020 Final Round
Question 19
The astronomical term axial precession describes the changing ...
Open questionIAAC — 2020 Final Round
Question 20
Which astronomical term describes the alignment of three celestial objects?
Open questionIAAC — 2020 Final Round
Question 21
The farthest point of a planet to the Sun is called ...
Open questionIAAC — 2020 Final Round
Question 22
What is a synodic month?
Open questionIAAC — 2020 Final Round
Question 23
The astronomical object Hale-Bopp is a ...
Open questionIAAC — 2020 Final Round
Question 24
The Olbers’ paradox raises the following question:
Open questionIAAC — 2020 Final Round
Question 25
The picture below shows a very close and well-known galaxy: What is the name of this galaxy?
Open questionIAAC — 2020 Final Round
Question 26
The correct astronomical term for shooting stars (or falling star) is ...
Open questionIAAC — 2020 Final Round
Question 27
The calculated age of the universe is ...
Open questionIAAC — 2020 Final Round
Question 28
What is expected to happen at the end of the Sun’s lifetime?
Open questionIAAC — 2020 Final Round
Question 29
Approximately how far away is the Sun from the centre of the Milky Way?
Open questionIAAC — 2020 Final Round
Question 30
Which one is the correct order of spectral classes according to the star’s surface temperature (from high to low)?
Open questionIAAC — 2020 Final Round
Question 31
A rocket that has accelerated to the second cosmic velocity can...
Open questionIAAC — 2020 Final Round
Question 32
What is the diameter of the observable universe in parsec?
Open questionIAAC — 2020 Final Round
Question 33
The well-known and very large volcano named Olympus Mons is located on ...
Open questionIAAC — 2020 Final Round
Question 34
About how many Earth days are one Mars day?
Open questionIAAC — 2020 Final Round
Question 35
The fascinating aurorae (or polar lights) are located in the ...
Open questionIAAC — 2020 Final Round
Question 36
In which year did humans first land and walk on the Moon?
Open questionIAAC — 2020 Final Round
Question 37
The term heliocentric means ...
Open questionIAAC — 2020 Final Round
Question 38
Saturn’s moon Titan has many lakes which are made of liquid ...
Open questionIAAC — 2020 Final Round
Question 39
Copernicus is located on our moon and refers to a well-known ...
Open questionIAAC — 2020 Final Round
Question 40
What type of nebula is the famous Orion Nebula?
Open questionIAAC — 2020 Final Round
Question 41
How is the path in the sky called that the Sun appears to cross within a year?
Open questionIAAC — 2020 Final Round
Question 42
Spectral line splitting caused by magnetic fields is called ...
Open questionIAAC — 2020 Final Round
Question 43
In which wavelengths is the cosmic background radiation concentrated?
Open questionIAAC — 2020 Final Round
Question 44
Kepler’s Laws state that the cube of a planet’s semi-major axis is proportional to the ...
Open questionIAAC — 2020 Final Round
Question 45
What is the astronomical term for the outer boundary of the Sun’s magnetic field?
Open questionIAAC — 2020 Final Round
Question 46
The angle between an inferior planet and the Sun when observed from Earth is called ...
Open questionIAAC — 2020 Final Round
Question 47
The summer solstice in the northern/southern hemisphere occurs in ...
Open questionIAAC — 2020 Final Round
Question 48
Absolute magnitude is a star’s apparent magnitude in a distance of ...
Open questionIAAC — 2020 Final Round
Question 49
What is the visible part of the Sun called?
Open questionIAAC — 2020 Final Round
Question 50
The average albedo of the Earth (planetary albedo) is between ...
Open questionIAAC — 2021 Final Round
Question 1
Which intense meteor shower peaks every year in August?
Open questionIAAC — 2021 Final Round
Question 2
The distance between two objects with equal mass is doubled. By how much does the gravitational force between the object...
Open questionIAAC — 2021 Final Round
Question 3
A spaceship accelerates at 150 m/s² from rest. How long does it take to reach a 1.2 km distant asteroid?
Open questionIAAC — 2021 Final Round
Question 4
What kind of radiation do pulsars emit?
Open questionIAAC — 2021 Final Round
Question 5
The gravitational potential energy E between two objects with a distance R to each other can be expressed as ...
Open questionIAAC — 2021 Final Round
Question 6
What instrument is commonly used to observe and study pulsars?
Open questionIAAC — 2021 Final Round
Question 7
What type of astronomical object are pulsars most commonly?
Open questionIAAC — 2021 Final Round
Question 8
The two coordinate axis of the Equatorial Coordinate System are called ...
Open questionIAAC — 2021 Final Round
Question 9
The Vernal equinox is the intersection point between ...
Open questionIAAC — 2021 Final Round
Question 10
The closest star system to the Earth is called Alpha Centauri. How many stars belong to the Alpha Centauri system?
Open questionIAAC — 2021 Final Round
Question 11
The picture below shows a satellite galaxy of the Milky Way: What is the name of this satellite galaxy?
Open questionIAAC — 2021 Final Round
Question 12
Stars from which spectral type have the lowest temperature?
Open questionIAAC — 2021 Final Round
Question 13
Which one of the following expressions is the Rankine-Hugoniot jump condition for the conservation of momentum through a...
Open questionIAAC — 2021 Final Round
Question 14
Which one of the following expressions is correct for the Lorentz factor γ and β = v/c?
Open questionIAAC — 2021 Final Round
Question 15
The intergalactic medium is permeated mainly by ...
Open questionIAAC — 2021 Final Round
Question 16
In a far-away solar system, a planet circles the main star with an orbital period of 100 days and a semi-major axis of 2...
Open questionIAAC — 2021 Final Round
Question 17
How is the part of a moon’s shadow called in which a total solar eclipse is possible?
Open questionIAAC — 2021 Final Round
Question 18
The diameter of the lens’ aperture of your telescope is 5 m and you observe at a wavelength of 1000 nm. What is the reso...
Open questionIAAC — 2021 Final Round
Question 19
A fast travelling spaceship has a Lorentz factor of γ = 3. This corresponds to a velocity v of ...
Open questionIAAC — 2021 Final Round
Question 20
Imagine that a total solar eclipse happens on the Earth today. What is the phase of the Moon on this day?
Open questionIAAC — 2021 Final Round
Question 21
The negative effect of incoming wavefront distortions on telescope images is reduced by using a system called ...
Open questionIAAC — 2021 Final Round
Question 22
You are given a list of stars and their apparent magnitude. Which one is the faintest star?
Open questionIAAC — 2021 Final Round
Question 23
The right ascension is measured in units of ...
Open questionIAAC — 2021 Final Round
Question 24
The Lyman-alpha line can be found at a wavelength of around ...
Open questionIAAC — 2021 Final Round
Question 25
Which transition is called Lyα lines?
Open questionIAAC — 2021 Final Round
Question 26
Below, you can see the rough sketch of a telescope. What type of telescope is drawn?
Open questionIAAC — 2021 Final Round
Question 27
An Analemma is a diagram showing the position of _____ from a fixed location and the same mean solar time over the cours...
Open questionIAAC — 2021 Final Round
Question 28
Which astronomical coordinate system uses the observer on Earth as a reference point?
Open questionIAAC — 2021 Final Round
Question 29
Which type of star is only stable due to the pressure of an electron gas?
Open questionIAAC — 2021 Final Round
Question 30
The colour of a star depends on the ...
Open questionIAAC — 2021 Final Round
Question 31
An object is moving with a velocity of 0.6c in your line of sight. What is the redshift z of this object?
Open questionIAAC — 2021 Final Round
Question 32
In which one of the following time frames after the Big Bang did the cosmic reionization process begin?
Open questionIAAC — 2021 Final Round
Question 33
Massive stars are essential for the universe because they ...
Open questionIAAC — 2021 Final Round
Question 34
The drawing below shows a comet in four positions around the Sun. For which position does the comet’s tail point in the...
Open questionIAAC — 2021 Final Round
Question 35
What spectral region can be observed from the Earth even when there are clouds in the sky?
Open questionIAAC — 2021 Final Round
Question 36
What was the last planet visited by Voyager 1?
Open questionIAAC — 2021 Final Round
Question 37
The time between two full moons is approximately ...
Open questionIAAC — 2021 Final Round
Question 38
Which one of the following objects is called a black dwarf in astronomy?
Open questionIAAC — 2021 Final Round
Question 39
Which planet has an axial tilt of 98 degrees?
Open questionIAAC — 2021 Final Round
Question 40
The smallest distance between Pluto and the Sun is about ...
Open questionIAAC — 2022 Final Round
Question 1
What is the name of the JWST component highlighted below?
Open questionIAAC — 2022 Final Round
Question 2
What is the name of the JWST component highlighted below?
Open questionIAAC — 2022 Final Round
Question 3
What is the name of the JWST component highlighted below?
Open questionIAAC — 2022 Final Round
Question 4
When a neutron star rotates, it becomes a ...
Open questionIAAC — 2022 Final Round
Question 5
If the Earth had the density of a neutron star, what would be the diameter of the Earth?
Open questionIAAC — 2022 Final Round
Question 6
Where in space is the JWST located?
Open questionIAAC — 2022 Final Round
Question 7
Two asteroids with masses m₁, m₂ and velocities v₁, v₂ collide horizontally and merge into a single object. What is the...
Open questionIAAC — 2022 Final Round
Question 8
Which one of these wavelengths is considered ultraviolet radiation?
Open questionIAAC — 2022 Final Round
Question 9
Which one of these wavelengths is considered infrared radiation?
Open questionIAAC — 2022 Final Round
Question 10
The planet’s albedo is the fraction of incident light ...
Open questionIAAC — 2022 Final Round
Question 11
Earth’s current average surface temperature is around ...
Open questionIAAC — 2022 Final Round
Question 12
Which of the following acronyms refers to an instrument of the JWST?
Open questionIAAC — 2022 Final Round
Question 13
A star has the luminosity L₀. The temperature T of the star doubles. How does the luminosity change?
Open questionIAAC — 2022 Final Round
Question 14
An object emits light at a wavelength of 200 nanometers. You receive the light at 1000 nanometers. What is the redshift...
Open questionIAAC — 2022 Final Round
Question 15
Why is it hard to observe the universe with infrared radiation from the Earth’s surface?
Open questionIAAC — 2022 Final Round
Question 16
The moment of inertia of a solid cylinder with radius R and mass M is given by ...
Open questionIAAC — 2022 Final Round
Question 17
Kepler’s 2nd law states that ...
Open questionIAAC — 2022 Final Round
Question 18
Scientists detect no CH₃OH and no NH₃ in the atmosphere of a sub-Neptune planet. What type of surface does this planet p...
Open questionIAAC — 2022 Final Round
Question 19
Sub-Neptune planets are ...
Open questionIAAC — 2022 Final Round
Question 20
The surface temperature (in °C) of the Sun is close to ...
Open questionIAAC — 2022 Final Round
Question 21
An object’s spectral energy distribution (SED) is formally given by ...
Open questionIAAC — 2022 Final Round
Question 22
Galileo discovered with his telescope that Venus ...
Open questionIAAC — 2022 Final Round
Question 24
Neptune’s diameter is similar to ...
Open questionIAAC — 2022 Final Round
Question 25
Compared to the Sun’s surface temperature, sunspots are ...
Open questionIAAC — 2022 Final Round
Question 26
The brightest star in the night sky is called ...
Open questionIAAC — 2022 Final Round
Question 27
Alpha Centauri is the closest star system to the Earth. It is located on the ...
Open questionIAAC — 2022 Final Round
Question 28
The atmosphere of Venus contains high amounts of ...
Open questionIAAC — 2022 Final Round
Question 29
What is the name of Jupiter’s moon shown in the figure below?
Open questionIAAC — 2022 Final Round
Question 30
The moon Titan orbits around ...
Open questionIAAC — 2023 Final Round
Question 1
Which one of these shapes (shown below) illustrates an elliptical galaxy?
Open questionIAAC — 2023 Final Round
Question 2
What is the class of the galaxy shown below?
Open questionIAAC — 2023 Final Round
Question 3
Which class of galaxies does the shape shown below illustrate?
Open questionIAAC — 2023 Final Round
Question 4
The speed of light is approximately ...
Open questionIAAC — 2023 Final Round
Question 5
What is the most common type of galaxy in the universe?
Open questionIAAC — 2023 Final Round
Question 6
How far away from Earth is a star with an observed parallax of 0.1 arcseconds?
Open questionIAAC — 2023 Final Round
Question 7
Which one of the labeled points on the ellipse shown below is the aphelion?
Open questionIAAC — 2023 Final Round
Question 8
What is true about the orbit of a comet called C/2023 A3?
Open questionIAAC — 2023 Final Round
Question 9
The term dark energy is related to ...
Open questionIAAC — 2023 Final Round
Question 10
Which landforms near the Zhurong landing site on Mars are likely related to volcanism?
Open questionIAAC — 2023 Final Round
Question 11
The gravitational acceleration at the surface of a star with average density ρ and radius R is given by ...
Open questionIAAC — 2023 Final Round
Question 12
The Zhurong Mars rover landed at an elevation of around ...
Open questionIAAC — 2023 Final Round
Question 13
Which instrument onboard the Zhurong Mars rover measures the magnetic field?
Open questionIAAC — 2023 Final Round
Question 14
Which object was historically the reference value m₀ for the apparent magnitude?
Open questionIAAC — 2023 Final Round
Question 15
About how much brighter is a star with an apparent magnitude of m = 1 compared to a star with an apparent magnitude of m...
Open questionIAAC — 2023 Final Round
Question 16
Hydrostatic equilibrium can best be described as the equilibrium between ...
Open questionIAAC — 2023 Final Round
Question 17
The ideal gas law states that ... (T: temperature, p: pressure, V: volume, N: number of particles, k: Boltzmann constant...
Open questionIAAC — 2023 Final Round
Question 19
Where on Mars did the Zhurong rover of the Tianwen-1 mission land?
Open questionIAAC — 2023 Final Round
Question 20
The colour of light with a wavelength of 700 nanometers is ...
Open questionIAAC — 2023 Final Round
Question 21
How high was the star formation rate in the Galactic Center in the past 10–100 billion years?
Open questionIAAC — 2023 Final Round
Question 22
The two young massive clusters near the Galactic Centre are called ...
Open questionIAAC — 2023 Final Round
Question 23
How far away is the centre of the Milky Way from Earth?
Open questionIAAC — 2023 Final Round
Question 24
The atmosphere of Mars consists primarily of ...
Open questionIAAC — 2023 Final Round
Question 25
Approximately how many stars are there in the Milky Way?
Open questionIAAC — 2023 Final Round
Question 26
The bending of starlight when it passes through a gravitational field is called ...
Open questionIAAC — 2023 Final Round
Question 27
The outermost layer of the Sun that is visible during a total solar eclipse is called the ...
Open questionIAAC — 2023 Final Round
Question 28
The fusion process that generates the Sun’s energy is called ...
Open questionIAAC — 2023 Final Round
Question 29
How does the temperature of a star affect the distribution of photon energies it emits?
Open questionIAAC — 2023 Final Round
Question 30
The asteroid belt of the solar system is between the orbits of ...
Open questionIAAC — 2024 Final Round
Question 1
Which one of these stars can be seen only in the Southern Hemisphere?
Open questionIAAC — 2024 Final Round
Question 2
Which one of these constellations can be seen only in the Southern Hemisphere?
Open questionIAAC — 2024 Final Round
Question 3
What kind of astronomical object is the Large Magellanic Cloud?
Open questionIAAC — 2024 Final Round
Question 4
How many stars are there in the Milky Way?
Open questionIAAC — 2024 Final Round
Question 5
On Earth’s surface, objects fall with a gravitational acceleration of approximately ...
Open questionIAAC — 2024 Final Round
Question 6
The cosmic microwave background can be detected using a ...
Open questionIAAC — 2024 Final Round
Question 7
The rotational speed at Earth’s equator is about 1,600 km/h. What is the rotational speed at Earth’s poles?
Open questionIAAC — 2024 Final Round
Question 8
Which latitude is best suited for a rocket launch?
Open questionIAAC — 2024 Final Round
Question 9
The altitude of the International Space Station (ISS) is around ...
Open questionIAAC — 2024 Final Round
Question 10
The ISS descends over time primarily due to ...
Open questionIAAC — 2024 Final Round
Question 11
Space is often considered to start at an altitude of ...
Open questionIAAC — 2024 Final Round
Question 12
What is the name of the region marked in the horizontal Milky Way drawing below?
Open questionIAAC — 2024 Final Round
Question 13
What is the name of the region marked in the horizontal Milky Way drawing below?
Open questionIAAC — 2024 Final Round
Question 14
Einstein rings are caused by ...
Open questionIAAC — 2024 Final Round
Question 15
What is the initial mass function (IMF) in astronomy?
Open questionIAAC — 2024 Final Round
Question 16
What is a spectral energy distribution (SED) plot in astronomy?
Open questionIAAC — 2024 Final Round
Question 17
Io is a moon of the planet ...
Open questionIAAC — 2024 Final Round
Question 18
Which spacecraft orbits currently around Jupiter?
Open questionIAAC — 2024 Final Round
Question 19
How do volcanoes at the poles of the moon Io differ from volcanoes at the equator?
Open questionIAAC — 2024 Final Round
Question 20
How many volcanic hot spots were observable on the surface of the moon Io between 2017 and 2022?
Open questionIAAC — 2024 Final Round
Question 21
Which mechanism causes volcanic activity on the moon Io?
Open questionIAAC — 2024 Final Round
Question 22
How many people have stepped on the moon as of 2024?
Open questionIAAC — 2024 Final Round
Question 23
Which one of these planets is never visible at midnight?
Open questionIAAC — 2024 Final Round
Question 24
Schmidt, Cassegrain, and Galilean are names for famous ...
Open questionIAAC — 2024 Final Round
Question 25
Most stars are cooler than the Sun and emit most of their energy as ...
Open questionIAAC — 2024 Final Round
Question 26
Astronomers use Cepheid stars as a measurement for ...
Open questionIAAC — 2025 Final Round
Question 1
What type of optical telescope is shown in the image below?
Open questionIAAC — 2025 Final Round
Question 2
What type of optical telescope is shown in the image below?
Open questionIAAC — 2025 Final Round
Question 3
Approximately how large is the diameter of the Sun?
Open questionIAAC — 2025 Final Round
Question 4
What is the distance between the Sun and the closest star?
Open questionIAAC — 2025 Final Round
Question 5
If the Sun had a diameter of a football (22 cm), what would be Earth’s diameter on this scale?
Open questionIAAC — 2025 Final Round
Question 6
One astronomical unit (AU) is equivalent to approximately ...
Open questionIAAC — 2025 Final Round
Question 7
What is the average density of the planet Earth?
Open questionIAAC — 2025 Final Round
Question 8
The gravitational acceleration experienced by an object of mass m at the surface of a planet with mass M and radius R eq...
Open questionIAAC — 2025 Final Round
Question 9
The Hubble parameter H(t) is connected to the cosmological scale factor a(t) by ...
Open questionIAAC — 2025 Final Round
Question 10
The unit of the Hubble constant H₀ is usually given as ...
Open questionIAAC — 2025 Final Round
Question 11
The current age of the universe is ...
Open questionIAAC — 2025 Final Round
Question 12
What are the two main components of comets?
Open questionIAAC — 2025 Final Round
Question 13
What are the two tails of a comet mainly made of?
Open questionIAAC — 2025 Final Round
Question 14
If the distance to a star doubles, the gravitational force it exerts becomes ...
Open questionIAAC — 2025 Final Round
Question 15
Cepheid variables are primarily important because they allow astronomers to measure ...
Open questionIAAC — 2025 Final Round
Question 16
If a Cepheid has a period of 30 days, compared to a 6-day Cepheid, it will be ...
Open questionIAAC — 2025 Final Round
Question 17
The distance modulus relates which two quantities?
Open questionIAAC — 2025 Final Round
Question 18
A star has an absolute magnitude of -2.0 and is located 1000 pc away. What is its apparent magnitude?
Open questionIAAC — 2025 Final Round
Question 19
A star has an apparent magnitude of 10.0 and is located 100 pc away. What is its absolute magnitude?
Open questionIAAC — 2025 Final Round
Question 20
The question of why the night sky is dark despite the vast number of stars is known as ...
Open questionIAAC — 2025 Final Round
Question 21
Why is the night sky dark, even though the universe contains billions of stars?
Open questionIAAC — 2025 Final Round
Question 22
In cosmology, the critical density determines ...
Open questionIAAC — 2025 Final Round
Question 23
If the density of the universe is smaller than the critical density, the universe is ...
Open questionIAAC — 2025 Final Round
Question 24
The Milky Way-Andromeda collision probability is mainly influenced by which smaller galaxies?
Open questionIAAC — 2025 Final Round
Question 25
Which galaxy tends to increase the probability of a Milky Way-Andromeda collision?
Open questionIAAC — 2025 Final Round
Question 26
Gravitational softening in simulations is introduced to ...
Open questionIAAC — 2025 Final Round
Question 27
The galaxy M31 is also called ...
Open questionIAAC — 2025 Final Round
Question 28
Which two galaxies are the dominant members of the Local Group?
Open questionIAAC — 2025 Final Round
Question 29
What is the currently expected timescale for a possible Milky Way-Andromeda merger?
Open questionIAAC — 2025 Final Round
Question 30
The perihelion distance is defined as ...
Open questionIAAC — 2025 Final Round
Question 31
The discovery of the object Ammonite (2023 KQ 14) was significant because it fills the ...
Open questionIAAC — 2025 Final Round
Question 32
The newly discovered Sedna-like object ‘Ammonite’ has a perihelion of ...
Open questionIAAC — 2025 Final Round
Question 33
Which hypothetical body is often proposed to explain Sedna-like orbits?
Open questionIAAC — 2025 Final Round
Question 34
Which element is most abundant in the universe?
Open questionIAAC — 2025 Final Round
Question 35
Which star will the Sun most likely become at the end of its life?
Open questionIAAC — 2025 Final Round
Question 36
Which planet has the fastest rotation period?
Open questionBAAO — 2016 Astronomy & Astrophysics A2 Challenge
Question 1
Why do hurricanes rotate anti-clockwise in the northern hemisphere and clockwise in the southern hemisphere?
Open questionBAAO — 2016 Astronomy & Astrophysics A2 Challenge
Question 2
Why are there two tides every day?
Open questionBAAO — 2016 Astronomy & Astrophysics A2 Challenge
Question 3
A typical cheap handheld telescope has a diameter of 10 cm, whilst ones for keen amateurs can have diameters of 40 cm. H...
Open questionBAAO — 2016 Astronomy & Astrophysics A2 Challenge
Question 4
Which of the following is not a zodiacal constellation, according to the astronomical definition?
Open questionBAAO — 2016 Astronomy & Astrophysics A2 Challenge
Question 5
When observing from the UK, during which season is the Full Moon visible highest in the sky?
Open questionBAAO — 2016 Astronomy & Astrophysics A2 Challenge
Question 6
Given an overwhelmingly large piece of paper, with a thickness of 10 μm, approximately how many times do you need to fol...
Open questionBAAO — 2016 Astronomy & Astrophysics A2 Challenge
Question 7
At a latitude of 52° N what is the altitude of Polaris above the horizon?
Open questionBAAO — 2016 Astronomy & Astrophysics A2 Challenge
Question 8
"Manhattanhenge" is the name given to when, just before sunset or just after sunrise 4 times a year (twice for setting,...
Open questionBAAO — 2016 Astronomy & Astrophysics A2 Challenge
Question 9
You travel 100 miles South, 100 miles East and 100 miles North and arrive back where you started. Where are you? You are...
Open questionBAAO — 2016 Astronomy & Astrophysics A2 Challenge
Question 10
On 5th September 2016, the Rosetta mission finally found the Philae lander on Comet 67P/Churyumov-Gerasimenko. Consideri...
Open questionBAAO — 2017 Astronomy & Astrophysics Challenge
Question 1
In 2015, physicists at the Laser Interferometer Gravitational-Wave Observatory (LIGO) announced the first-ever observati...
Open questionBAAO — 2017 Astronomy & Astrophysics Challenge
Question 2
In which constellation would you find the centre of the Milky Way?
Open questionBAAO — 2017 Astronomy & Astrophysics Challenge
Question 3
What is the approximate average thickness of Saturn's rings?
Open questionBAAO — 2017 Astronomy & Astrophysics Challenge
Question 4
Pluto has roughly the same surface area as which country?
Open questionBAAO — 2017 Astronomy & Astrophysics Challenge
Question 5
In the video game Halo, players are able to move around on the inner edge of a ring structure, which has a radius of 500...
Open questionBAAO — 2017 Astronomy & Astrophysics Challenge
Question 6
What is the declination of the Sun on the Winter solstice?
Open questionBAAO — 2017 Astronomy & Astrophysics Challenge
Question 7
Which of the following cities will experience the longest day during June?
Open questionBAAO — 2017 Astronomy & Astrophysics Challenge
Question 8
If a planet orbits the Sun with a semi-major axis of 4 AU, what is the period of its orbit?
Open questionBAAO — 2017 Astronomy & Astrophysics Challenge
Questions 9–10
Two light sources, A and B, emitting their light isotropically (i.e. equally in all directions) are placed at distance r...
Open questionBAAO — 2018 Astronomy & Astrophysics Challenge
Question 1
For a satellite in a circular orbit around the Earth, which of the arrows in the figure below describe the direction of...
Open questionBAAO — 2018 Astronomy & Astrophysics Challenge
Question 2
The tail of a comet
Open questionBAAO — 2018 Astronomy & Astrophysics Challenge
Question 3
Meteor showers are caused by
Open questionBAAO — 2018 Astronomy & Astrophysics Challenge
Question 4
Looking up into the UK sky at 10pm in late September, which of the following bright stars is NOT visible?
Open questionBAAO — 2018 Astronomy & Astrophysics Challenge
Question 5
The three stars that make up Orion's belt are Alnitak, Alnilam and Mintaka, with apparent magnitudes, m, of 1.77, 1.69 a...
Open questionBAAO — 2018 Astronomy & Astrophysics Challenge
Questions 6–7
A comet is orbiting the Sun in an orbit with a semi-major axis of 5.0 au and an eccentricity, e = 0.80. Calculate its se...
Open questionBAAO — 2018 Astronomy & Astrophysics Challenge
Question 8
On the evening of 27th July 2018, there was a total lunar eclipse (where the Moon passes into the Earth's shadow). As vi...
Open questionBAAO — 2018 Astronomy & Astrophysics Challenge
Question 9
Light from a star is split into a line spectrum of different colours. The line spectrum from the star is shown, along wi...
Open questionBAAO — 2018 Astronomy & Astrophysics Challenge
Question 10
'Oumuamua is an elongated interstellar comet. During an observation with a ground-based telescope whilst close to the Su...
Open questionBAAO — 2019 Astronomy & Astrophysics Challenge
Question 1
The image below was released in April 2019 by the Event Horizon Telescope collaboration and is considered to be one of t...
Open questionBAAO — 2019 Astronomy & Astrophysics Challenge
Question 2
Where on the Moon did astronauts walk in July 1969?
Open questionBAAO — 2019 Astronomy & Astrophysics Challenge
Question 3
The Chandra X-ray Observatory celebrates 20 years of operation this year, and was 100 times more sensitive than previous...
Open questionBAAO — 2019 Astronomy & Astrophysics Challenge
Question 4
Looking up into the UK night sky in late September, which of the following bright stars rises first?
Open questionBAAO — 2019 Astronomy & Astrophysics Challenge
Question 5
In May 1919 the British astronomers Frank Watson Dyson and Arthur Stanley Eddington organised for two teams to photograp...
Open questionBAAO — 2019 Astronomy & Astrophysics Challenge
Question 6
An observer in the UK sees a full moon in the constellation of Capricorn. What time of year is it?
Open questionBAAO — 2019 Astronomy & Astrophysics Challenge
Question 7
Earth’s moon has a radius of 1737 km and Titan (one of Saturn’s moons) has a radius of 2576 km. At the surface, their gr...
Open questionBAAO — 2019 Astronomy & Astrophysics Challenge
Question 8
The One-Mile Telescope is a radio telescope just outside Cambridge that has three dishes that can be spread out up to on...
Open questionBAAO — 2019 Astronomy & Astrophysics Challenge
Question 9
There are approximately 450 geostationary satellites currently in orbit. They have an orbital period of 1 day and orbit...
Open questionBAAO — 2019 Astronomy & Astrophysics Challenge
Question 10
On the 1st January 2019 the New Horizons probe (having successfully flown by Pluto in 2015) had an encounter with the Ku...
Open questionBAAO — 2020 Astronomy & Astrophysics Challenge
Question 1
The year 1990 held many exciting events in astronomy. Which of the following did not celebrate its 30th anniversary this...
Open questionBAAO — 2020 Astronomy & Astrophysics Challenge
Question 2
Which well-known star dropped in brightness by 40% between October 2019 and April 2020, leading to speculation it may be...
Open questionBAAO — 2020 Astronomy & Astrophysics Challenge
Question 3
A very strong argument for the existence of dark matter is:
Open questionBAAO — 2020 Astronomy & Astrophysics Challenge
Question 4
The Ring Nebula, M57, is surrounded by thin shells of out-flowing material, the outermost (and faintest) of which is mea...
Open questionBAAO — 2020 Astronomy & Astrophysics Challenge
Question 5
Which of these constellations is entirely south of the ecliptic?
Open questionBAAO — 2020 Astronomy & Astrophysics Challenge
Question 6
For an observer at a latitude of 52°, which of these stars culminates with the highest altitude?
Open questionBAAO — 2020 Astronomy & Astrophysics Challenge
Question 7
On 21st March the Sun is in the constellation of Pisces. In which of these constellations would it be possible to find V...
Open questionBAAO — 2020 Astronomy & Astrophysics Challenge
Question 8
When an exoplanet transits a star, the brightness of the star dims by 0.0557 magnitudes. Let Rₚ be the radius of the pla...
Open questionBAAO — 2020 Astronomy & Astrophysics Challenge
Question 9
The event horizon of a non-spinning, uncharged black hole can be thought of as a sphere with a radius equal to the Schwa...
Open questionBAAO — 2020 Astronomy & Astrophysics Challenge
Question 10
On 19th July 2020 the first Arab interplanetary mission was launched on its way to Mars, consisting of the Hope probe de...
Open questionBAAO — 2021 Astronomy & Astrophysics Challenge
Question 1
As of September 2021, which of the following billionaires has not been into space (defined as at least 80 km above the s...
Open questionBAAO — 2021 Astronomy & Astrophysics Challenge
Question 2
The website what3words splits up the Earth’s surface into 3 m × 3 m squares and gives a co-ordinate of three randomly ch...
Open questionBAAO — 2021 Astronomy & Astrophysics Challenge
Question 3
After many delays, the James Webb Space Telescope (JWST) is due to be launched in December 2021. This will be the succes...
Open questionBAAO — 2021 Astronomy & Astrophysics Challenge
Question 4
For which of these lines of latitude will a vertical stick in the ground have no shadow at local midday on 21st December...
Open questionBAAO — 2021 Astronomy & Astrophysics Challenge
Question 5
When Mars has its opposition in 2022, an observer in the UK will see it in Taurus. In roughly which month will this oppo...
Open questionBAAO — 2021 Astronomy & Astrophysics Challenge
Question 6
In which constellation is Saturn visible during Autumn 2021? [Hint: it is close to Jupiter, which spent most of Summer 2...
Open questionBAAO — 2021 Astronomy & Astrophysics Challenge
Question 7
Which of these stars are closest to the Sun in October 2021?
Open questionBAAO — 2021 Astronomy & Astrophysics Challenge
Question 8
Estimate the number of photons incident on a human pupil (of radius 2mm) from the Sun per second when it is at the zenit...
Open questionBAAO — 2021 Astronomy & Astrophysics Challenge
Question 9
A comet orbits the Sun with a period of 172 years and eccentricity 0.94. It is currently at a distance of 60 au away fro...
Open questionBAAO — 2021 Astronomy & Astrophysics Challenge
Question 10
In the rotating reference frame where the Earth is stationary, an asteroid orbits the Sun in 3.5 years. What is the dist...
Open questionBAAO — 2022 Astronomy & Astrophysics Challenge
Question 1
Below is one of the first images taken with the James Webb Space Telescope (JWST) released to the public on 12th July 20...
Open questionBAAO — 2022 Astronomy & Astrophysics Challenge
Question 2
In Autumn 2022, NASA plans to launch a practice mission in preparation for sending humans back to the Moon. What is the...
Open questionBAAO — 2022 Astronomy & Astrophysics Challenge
Question 3
A telescope with a focal length of 750 mm is used with an eyepiece. Which eyepiece focal length would give the greatest...
Open questionBAAO — 2022 Astronomy & Astrophysics Challenge
Question 4
The Gaia spacecraft, launched in 2013, is designed to map the sky with unprecedented precision. Its third data release (...
Open questionBAAO — 2022 Astronomy & Astrophysics Challenge
Question 5
In September 2022, Jupiter reached opposition a few days after the autumnal equinox. Which constellation was it in at th...
Open questionBAAO — 2022 Astronomy & Astrophysics Challenge
Question 6
An observer on the equator sees the Moon rise at 22:00. Ignoring the inclination and eccentricity of the Moon’s orbit, w...
Open questionBAAO — 2022 Astronomy & Astrophysics Challenge
Question 7
Which of these stars will culminate at the highest altitude as seen by an observer in Oxford (latitude 51.75° N, longitu...
Open questionBAAO — 2022 Astronomy & Astrophysics Challenge
Question 8
The cubesat CAPSTONE will enter a near-rectilinear halo orbit (NRHO) of the Moon on 13th November 2022 as a direct test...
Open questionBAAO — 2022 Astronomy & Astrophysics Challenge
Question 9
An asteroid in a circular orbit around the Sun is at its closest to Earth every 300 days. What is its orbital speed? Ass...
Open questionBAAO — 2022 Astronomy & Astrophysics Challenge
Question 10
Jupiter’s apparent magnitude at opposition in 2022 of m = −2.94 is the brightest for ∼ 70 years due to it happening clos...
Open questionBAAO — 2023 Astronomy & Astrophysics Challenge
Question 1
SaxaVord is due to be one of the UK’s newest spaceports, with first launches planned in late 2023. Where is it based?
Open questionBAAO — 2023 Astronomy & Astrophysics Challenge
Question 2
In a given system, for all circular orbits of period T and orbital speed v, which of the following quantities is the sam...
Open questionBAAO — 2023 Astronomy & Astrophysics Challenge
Question 3
The recent supernova SN 2023ixf was one of the closest to Earth of the past decade, reaching an apparent magnitude of 10...
Open questionBAAO — 2023 Astronomy & Astrophysics Challenge
Question 4
In August 2023, India became the fourth country to successfully land a spacecraft on the Moon. The Chandrayaan 3 mission...
Open questionBAAO — 2023 Astronomy & Astrophysics Challenge
Question 5
From which of these settlements can a geostationary satellite not be seen?
Open questionBAAO — 2023 Astronomy & Astrophysics Challenge
Question 6
What is the Messier number of this object?
Open questionBAAO — 2023 Astronomy & Astrophysics Challenge
Question 7
Which of the following stars is in the constellation Taurus?
Open questionBAAO — 2023 Astronomy & Astrophysics Challenge
Question 8
Which of these constellations contains the nearest (comparable size) galaxy to the Milky Way?
Open questionBAAO — 2023 Astronomy & Astrophysics Challenge
Question 9
An observer in the UK sees a third quarter moon in the constellation Capricornus. What is the month?
Open questionBAAO — 2023 Astronomy & Astrophysics Challenge
Question 10
On the 21st June the Sun sets in Guernsey (49.45° N, 2.59° W) at 21:00 BST (British Summer Time, BST = UT+1). At what ti...
Open questionBAAO — 2024 Astronomy & Astrophysics Challenge
Question 1
The year 2024 marks the 10th anniversary of the landing by which of the following spacecraft?
Open questionBAAO — 2024 Astronomy & Astrophysics Challenge
Question 2
If the Moon appears to be exactly half illuminated by the Sun, what is the Sun-Earth-Moon angle, assuming the Earth and...
Open questionBAAO — 2024 Astronomy & Astrophysics Challenge
Question 3
Using Hubble’s law for recessional velocities of distant objects, find a possible expression to estimate the recessional...
Open questionBAAO — 2024 Astronomy & Astrophysics Challenge
Question 4
T Coronae Borealis (T CrB), nicknamed the Blaze Star, is a binary star system about 920 pc away in the constellation Cor...
Open questionBAAO — 2024 Astronomy & Astrophysics Challenge
Question 5
The Euclid space mission, launched in 2023, will image 36% of the sky in extremely high resolution to investigate the na...
Open questionBAAO — 2024 Astronomy & Astrophysics Challenge
Question 6
An observer is lost at sea and sees that Polaris is 33° above the horizon. What is their latitude?
Open questionBAAO — 2024 Astronomy & Astrophysics Challenge
Question 7
Which of the following constellations is south of the celestial equator?
Open questionBAAO — 2024 Astronomy & Astrophysics Challenge
Question 8
Which of the following Messier objects is a nebula that can be found in the same constellation as the star Aldebaran?
Open questionBAAO — 2024 Astronomy & Astrophysics Challenge
Question 9
Which of these stars will culminate at the highest altitude, as seen by an observer in Rio de Janeiro (22.91° S, 43.17°...
Open questionBAAO — 2024 Astronomy & Astrophysics Challenge
Question 10
Between September 2024 and January 2025, Mars, Saturn, Uranus, and Neptune will all be in opposition: Mars in Gemini, Sa...
Open question