Space and Astronomy Quiz
Planets, black holes and Moon landings: 15 questions on how much of the cosmos you really know.
What planet is known as the Red Planet?
Got a hunch? Pick the answer that feels right.
Mars
Mars looks red because its surface is coated in iron oxide, essentially rust, which scatters sunlight toward the red end of the spectrum.
Mars is home to Olympus Mons, a volcano about two and a half times the height of Mount Everest.
What is the largest planet in our solar system?
Got a hunch? Pick the answer that feels right.
Jupiter
Jupiter is about 11 times wider than Earth and more than twice as massive as all the other planets in the solar system combined.
A day on Jupiter lasts under 10 hours, the shortest of any planet, which is why it visibly bulges at the equator.
How long does it take light from the Sun to reach Earth?
Got a hunch? Pick the answer that feels right.
About 8 minutes
Sunlight covers roughly 150 million kilometers at 300,000 kilometers per second, so it takes about 8 minutes and 20 seconds to arrive.
If the Sun vanished, Earth would keep orbiting normally for those same eight minutes, since gravity also travels at the speed of light.
What was the first human-made object to reach the surface of the Moon?
Got a hunch? Pick the answer that feels right.
Luna 2 (Soviet probe)
The Soviet probe Luna 2 crashed into the Moon on September 13, 1959, almost a decade before Apollo 11's crewed landing.
Luna 9 achieved the first soft landing in 1966, sending back the first photographs taken from the lunar surface.
Which planet has the most moons in our solar system?
Got a hunch? Pick the answer that feels right.
Saturn
Saturn leads with 293 moons on confirmed orbits as of mid-2026, well ahead of Jupiter's 115, after batches of small outer moons were confirmed in 2023, 2025 and 2026.
Saturn's largest moon, Titan, is bigger than the planet Mercury and has lakes of liquid methane on its surface.
What is the name of the galaxy that contains our solar system?
Got a hunch? Pick the answer that feels right.
Milky Way
The Milky Way is a barred spiral galaxy containing 100 to 400 billion stars, and the Sun sits in one of its outer arms, about two thirds of the way out from the center.
Andromeda, our nearest large galactic neighbor, is on course to merge with the Milky Way in about 4.5 billion years.
What is a light-year a measurement of?
Got a hunch? Pick the answer that feels right.
Distance
A light-year is the distance light travels in one year, about 9.46 trillion kilometers, so it measures distance rather than time despite the name.
Astronomers also use the parsec, equal to about 3.26 light-years, for measuring distances to stars.
Which space telescope was launched in 1990 and orbits Earth?
Got a hunch? Pick the answer that feels right.
Hubble
Hubble launched aboard the space shuttle Discovery in April 1990 and orbits about 540 kilometers up, above the blurring effects of Earth's atmosphere.
A flaw in Hubble's main mirror made its early images blurry until astronauts fitted corrective optics in 1993.
What is the hottest planet in our solar system?
Got a hunch? Pick the answer that feels right.
Venus
Venus averages about 465 degrees Celsius because its thick carbon dioxide atmosphere traps heat in a runaway greenhouse effect, beating Mercury despite being farther out.
Venus spins backward compared with most planets, and a single Venusian day is longer than its year.
Who was the first human to walk on the Moon?
Got a hunch? Pick the answer that feels right.
Neil Armstrong
Armstrong stepped onto the Sea of Tranquility on July 20, 1969, followed by Buzz Aldrin about 19 minutes later, while Michael Collins orbited above.
Yuri Gagarin was the first person in space in April 1961, and John Glenn was the first American to orbit Earth in 1962.
What object forms when the core of a very massive star collapses so completely that not even light can escape its gravity?
Got a hunch? Pick the answer that feels right.
Black hole
When a star of roughly 20 or more solar masses runs out of fuel, its core collapses past the point where any known force can stop it, forming a black hole.
Lighter collapsing cores stop as neutron stars, city-sized objects so dense that a teaspoon of their material would weigh billions of tons.
What is the closest star to Earth (besides the Sun)?
Got a hunch? Pick the answer that feels right.
Proxima Centauri
Proxima Centauri is a faint red dwarf about 4.24 light-years away, slightly closer than its companions Alpha Centauri A and B.
Proxima hosts at least one confirmed planet, Proxima b, which orbits within the star's habitable zone.
Which planet rotates on its side with an axial tilt of about 98 degrees?
Got a hunch? Pick the answer that feels right.
Uranus
Uranus tilts at about 98 degrees, so it effectively rolls around the Sun on its side, giving each pole 42 years of sunlight followed by 42 years of darkness.
Uranus was the first planet discovered with a telescope, spotted by William Herschel in 1781.
What is the name of the boundary where the Sun's solar wind stops?
Got a hunch? Pick the answer that feels right.
Heliopause
The heliopause is where the outward pressure of the solar wind is balanced by the interstellar medium, marking the edge of the Sun's bubble, the heliosphere.
Voyager 1 crossed the heliopause in 2012 and Voyager 2 followed in 2018, becoming the first spacecraft to enter interstellar space.
Approximately how old is the universe?
Got a hunch? Pick the answer that feels right.
13.8 billion years
Measurements of the cosmic microwave background by the Planck satellite put the universe's age at about 13.8 billion years since the Big Bang.
Earth and the rest of the solar system formed much later, about 4.6 billion years ago.
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All Science quizzes →About the Space and Astronomy Quiz
The Sun holds 99.8 percent of the mass of the solar system, Jupiter's Great Red Spot is a storm wider than Earth that has raged for at least 190 years, and the light you see from the Andromeda Galaxy left it around 2.5 million years ago. Astronomers keep adding to the tally: dozens of new moons were confirmed around the giant planets in 2026 alone.
These 15 questions range from the planets of our solar system to the Moon landings, space telescopes, black holes and the outer edge of the Sun's influence. The early questions are friendly to beginners, while a few later ones will stretch anyone who has not opened a science book since school. It suits students, stargazers and anyone who enjoys a good documentary.
You will find 15 multiple choice questions here, each with four options. Difficulty: Medium. Most people finish in about 6 minutes, and every answer comes with a short explanation and one extra fact worth keeping.
How to play
Read the question and pick one of the four answers. The correct answer is revealed straight away with a short explanation, then press Next question to keep going. At the end you get your score out of 15 and a full review of your round. Play again any time and the questions arrive in a fresh order. There is no timer and no account.
Good to know before you play
What topics does the Space and Astronomy Quiz cover?
Planets, moons, stars, galaxies, black holes, NASA and Soviet missions, space telescopes and the age of the universe. Every answer has an instant explanation.
Are the facts up to date?
Yes. Moon counts, distances and mission records were checked against NASA, ESA and International Astronomical Union figures as of 2026.
How many planets are in the solar system?
Eight: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Pluto was reclassified as a dwarf planet by the International Astronomical Union in 2006.
Answer key: all 15 questions with explanations
- What planet is known as the Red Planet?
Mars Mars looks red because its surface is coated in iron oxide, essentially rust, which scatters sunlight toward the red end of the spectrum. Mars is home to Olympus Mons, a volcano about two and a half times the height of Mount Everest. - What is the largest planet in our solar system?
Jupiter Jupiter is about 11 times wider than Earth and more than twice as massive as all the other planets in the solar system combined. A day on Jupiter lasts under 10 hours, the shortest of any planet, which is why it visibly bulges at the equator. - How long does it take light from the Sun to reach Earth?
About 8 minutes Sunlight covers roughly 150 million kilometers at 300,000 kilometers per second, so it takes about 8 minutes and 20 seconds to arrive. If the Sun vanished, Earth would keep orbiting normally for those same eight minutes, since gravity also travels at the speed of light. - What was the first human-made object to reach the surface of the Moon?
Luna 2 (Soviet probe) The Soviet probe Luna 2 crashed into the Moon on September 13, 1959, almost a decade before Apollo 11's crewed landing. Luna 9 achieved the first soft landing in 1966, sending back the first photographs taken from the lunar surface. - Which planet has the most moons in our solar system?
Saturn Saturn leads with 293 moons on confirmed orbits as of mid-2026, well ahead of Jupiter's 115, after batches of small outer moons were confirmed in 2023, 2025 and 2026. Saturn's largest moon, Titan, is bigger than the planet Mercury and has lakes of liquid methane on its surface. - What is the name of the galaxy that contains our solar system?
Milky Way The Milky Way is a barred spiral galaxy containing 100 to 400 billion stars, and the Sun sits in one of its outer arms, about two thirds of the way out from the center. Andromeda, our nearest large galactic neighbor, is on course to merge with the Milky Way in about 4.5 billion years. - What is a light-year a measurement of?
Distance A light-year is the distance light travels in one year, about 9.46 trillion kilometers, so it measures distance rather than time despite the name. Astronomers also use the parsec, equal to about 3.26 light-years, for measuring distances to stars. - Which space telescope was launched in 1990 and orbits Earth?
Hubble Hubble launched aboard the space shuttle Discovery in April 1990 and orbits about 540 kilometers up, above the blurring effects of Earth's atmosphere. A flaw in Hubble's main mirror made its early images blurry until astronauts fitted corrective optics in 1993. - What is the hottest planet in our solar system?
Venus Venus averages about 465 degrees Celsius because its thick carbon dioxide atmosphere traps heat in a runaway greenhouse effect, beating Mercury despite being farther out. Venus spins backward compared with most planets, and a single Venusian day is longer than its year. - Who was the first human to walk on the Moon?
Neil Armstrong Armstrong stepped onto the Sea of Tranquility on July 20, 1969, followed by Buzz Aldrin about 19 minutes later, while Michael Collins orbited above. Yuri Gagarin was the first person in space in April 1961, and John Glenn was the first American to orbit Earth in 1962. - What object forms when the core of a very massive star collapses so completely that not even light can escape its gravity?
Black hole When a star of roughly 20 or more solar masses runs out of fuel, its core collapses past the point where any known force can stop it, forming a black hole. Lighter collapsing cores stop as neutron stars, city-sized objects so dense that a teaspoon of their material would weigh billions of tons. - What is the closest star to Earth (besides the Sun)?
Proxima Centauri Proxima Centauri is a faint red dwarf about 4.24 light-years away, slightly closer than its companions Alpha Centauri A and B. Proxima hosts at least one confirmed planet, Proxima b, which orbits within the star's habitable zone. - Which planet rotates on its side with an axial tilt of about 98 degrees?
Uranus Uranus tilts at about 98 degrees, so it effectively rolls around the Sun on its side, giving each pole 42 years of sunlight followed by 42 years of darkness. Uranus was the first planet discovered with a telescope, spotted by William Herschel in 1781. - What is the name of the boundary where the Sun's solar wind stops?
Heliopause The heliopause is where the outward pressure of the solar wind is balanced by the interstellar medium, marking the edge of the Sun's bubble, the heliosphere. Voyager 1 crossed the heliopause in 2012 and Voyager 2 followed in 2018, becoming the first spacecraft to enter interstellar space. - Approximately how old is the universe?
13.8 billion years Measurements of the cosmic microwave background by the Planck satellite put the universe's age at about 13.8 billion years since the Big Bang. Earth and the rest of the solar system formed much later, about 4.6 billion years ago.
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