57 Space Trivia Questions and Answers, From the Solar System to the Edge of the Universe

Space trivia has an unfair advantage over every other category. In a history round you can often guess the plausible answer; in a space round the plausible answer is usually wrong, because the universe is under no obligation to be reasonable. It rains sulphuric acid on Venus and it never reaches the ground. A day there lasts longer than its year. Saturn is less dense than water. Astronauts float not because gravity has stopped but because they are falling, continuously, and missing the planet.

What follows is 57 questions and answers, grouped by theme, each with a sentence of context so the fact has something to hold on to. They suit a quiz night, a classroom starter or a long drive, and several exist mainly to correct something almost everyone believes.

Solar System Trivia Questions

1. Which is the hottest planet in the solar system? Answer: Venus, at around 465°C (869°F) — hotter than Mercury despite being nearly twice as far from the Sun, because its thick carbon dioxide atmosphere traps heat in a runaway greenhouse.

2. Which planet has a day longer than its year? Answer: Venus — it turns once on its axis roughly every 243 Earth days, while a full orbit of the Sun takes about 225.

3. Which planet orbits tipped almost entirely on its side? Answer: Uranus, with an axial tilt of about 98 degrees, probably the result of an enormous collision early in its history.

4. Which planet would float in water, given a large enough bath? Answer: Saturn — its average density is about 0.69 grams per cubic centimetre, below water's 1.0, because it is mostly hydrogen and helium.

5. Where is the tallest volcano in the solar system? Answer: Mars, where Olympus Mons rises about 22 km (13.6 miles), roughly two and a half times the height of Everest above sea level.

6. Why is Pluto no longer classified as a planet? Answer: Under the definition adopted by the International Astronomical Union in 2006, a planet must have cleared its orbital neighbourhood, and Pluto shares its region with countless Kuiper Belt objects.

7. Is the asteroid belt a dangerous, crowded field of rocks? Answer: No — its objects are typically hundreds of thousands of kilometres apart, and the whole belt's mass is only about 3% of the Moon's. Spacecraft cross it without dodging anything.

8. Which planet has the most known moons? Answer: Saturn, with more than 140 confirmed and the number still rising as surveys pick out smaller fragments. Jupiter is close behind, and the lead has changed hands more than once.

Moon Trivia Questions

1. Is there a dark side of the Moon? Answer: No. There is a far side, which never faces Earth, but it gets just as much sunlight as the near side over a lunar month.

2. Why do we always see the same face of the Moon? Answer: Tidal locking — the Moon rotates once on its axis in exactly the time it takes to orbit Earth, so the same hemisphere stays turned towards us.

3. How long does moonlight take to reach Earth? Answer: About 1.3 seconds, which is why the radio delay in the Apollo transmissions is audible if you listen to the recordings.

4. Is the Moon getting closer to Earth or further away? Answer: Further, by about 3.8 cm (1.5 inches) a year, measured by bouncing lasers off reflectors left on the surface by Apollo crews.

5. How big is the Moon compared with Earth? Answer: Its diameter is about 3,475 km (2,159 miles), roughly a quarter of Earth's — unusually large relative to its planet by solar system standards.

6. Where did the Moon come from? Answer: The leading explanation is a giant impact around 4.5 billion years ago, when a Mars-sized body struck the young Earth and the debris settled into orbit.

7. Will the Apollo footprints last forever? Answer: Not forever, but for a very long time. There is no wind or rain to erase them, though micrometeorites will erode them over millions of years.

8. What causes ocean tides? Answer: Mostly the Moon's gravity, which raises a bulge of water on the side facing it and another opposite; the Sun contributes roughly half as much again.

Stars and Galaxies Trivia Questions

1. What is the nearest star to the Sun? Answer: Proxima Centauri, about 4.24 light years away — far enough that no spacecraft we have built could reach it in a human lifetime.

2. What exactly is a light year? Answer: A distance, not a time: roughly 9.46 trillion km (5.88 trillion miles), the distance light travels in a year.

3. Which stars are hotter, blue ones or red ones? Answer: Blue. The hottest stars exceed 30,000°C at the surface, while red stars are coolest at around 3,000°C — the reverse of the colour coding on a bathroom tap.

4. What shape is the Milky Way, and where are we in it? Answer: A barred spiral roughly 100,000 light years across, with the Sun about 26,000 light years from the centre, out in a minor arm.

5. Which galaxy is heading towards us? Answer: Andromeda, about 2.5 million light years away; on current estimates the two galaxies will begin merging in around four billion years.

6. What is at the centre of the Milky Way? Answer: A supermassive black hole called Sagittarius A*, about four million times the mass of the Sun, imaged by the Event Horizon Telescope collaboration in 2022.

7. Why does looking at distant galaxies mean looking into the past? Answer: Light takes time to travel, so a galaxy a million light years away appears as it was a million years ago. Every telescope points backwards in time.

8. What happens to a star when it dies? Answer: It depends on mass. A star like the Sun swells into a red giant and sheds its layers to leave a white dwarf; a much heavier star explodes as a supernova, leaving a neutron star or a black hole.

Space Exploration History Trivia Questions

1. What was the first artificial satellite, and when was it launched? Answer: Sputnik 1, launched by the Soviet Union on 4 October 1957 — a polished metal sphere the size of a beach ball, beeping on a frequency amateurs everywhere could tune into.

2. Who was the first human in space? Answer: Yuri Gagarin, on 12 April 1961, aboard Vostok 1. The flight lasted 108 minutes and completed a single orbit.

3. Who was the first woman in space? Answer: Valentina Tereshkova, launched on 16 June 1963 aboard Vostok 6 — two decades before the first American woman flew.

4. Who performed the first spacewalk? Answer: Alexei Leonov, in March 1965, for about twelve minutes. His suit ballooned in the vacuum and he had to bleed off pressure to get back through the airlock.

5. When did humans first land on the Moon, and who was left in orbit? Answer: 20 July 1969, when Neil Armstrong and Buzz Aldrin landed Apollo 11's lunar module while Michael Collins stayed in the command module above.

6. What was the first spacecraft to land successfully on another planet? Answer: Venera 7, which reached the surface of Venus in December 1970 and transmitted for around 23 minutes before the heat and pressure ended it.

7. Which spacecraft launched in 1977 is now in interstellar space? Answer: Voyager 1, launched on 5 September 1977, which crossed the heliopause in 2012 and became the first human object to leave the Sun's bubble.

8. What went wrong with the Hubble Space Telescope after its 1990 launch? Answer: Its primary mirror had been ground to the wrong shape by a tiny margin, blurring every image. A servicing mission in 1993 fitted corrective optics, and it has worked since.

9. When was the first planet found orbiting another Sun-like star? Answer: 1995, when Michel Mayor and Didier Queloz announced 51 Pegasi b, a gas giant circling its star in about four days. They shared the 2019 Nobel Prize in Physics.

Astronauts and Life in Orbit Trivia Questions

1. Why do astronauts float on the International Space Station? Answer: Not because gravity has vanished — at that altitude it is still about 90% as strong as at the surface. They float because the station and everyone in it are in continuous free fall, moving sideways fast enough to keep missing the planet.

2. Is the Great Wall of China visible from space with the naked eye? Answer: No. It is long but only a few metres wide, and the same colour as the ground beside it. Astronauts, including China's first, Yang Liwei, have confirmed they could not see it unaided.

3. How many sunrises does an astronaut on the ISS see in a day? Answer: About sixteen — the station travels at roughly 28,000 km/h (17,500 mph) and orbits every 90 minutes.

4. Do astronauts grow taller in space? Answer: Yes, by up to around 5 cm (2 inches), as the spine decompresses without gravity squashing it. The gain vanishes within days of landing.

5. Why do astronauts have to exercise for about two hours a day? Answer: Without the constant load of gravity, weight-bearing bones can lose around 1% of their density a month, and muscle wastes alongside.

6. Can you cry in space? Answer: You can produce tears, but they do not fall. Surface tension holds them in a wobbling ball against the eye until something wipes it away.

7. Why are salt and pepper supplied as liquids on the ISS? Answer: Loose grains would drift into eyes, filters and instruments, so both are dissolved and dispensed as drops.

8. What would actually happen to an unprotected human in vacuum? Answer: You would not explode or freeze instantly. You would have roughly 15 seconds of useful consciousness before oxygen starvation took over, with swelling and boiling of body fluids following.

Physics and the Universe Trivia Questions

1. How fast does light travel, and how long does sunlight take to reach us? Answer: 299,792,458 metres per second, a figure now fixed by definition. Sunlight takes about 8 minutes and 20 seconds to reach us, so you always see the Sun as it was.

2. Why is the night sky dark? Answer: Known as Olbers' paradox — in an infinite, eternal universe every line of sight would end on a star and the sky would blaze. It is dark because the universe has a finite age and is expanding, so most of that light has either not arrived or has been stretched out of the visible range.

3. How fast must something travel to escape Earth's gravity? Answer: About 11.2 km/s, roughly 40,300 km/h (25,000 mph). From the Moon it is only about 2.4 km/s, which is why the lunar module needed so small an engine.

4. Is there sound in space? Answer: No, in the sense that matters — sound needs a medium to carry pressure waves, and space is near-vacuum. Inside a spacecraft, where there is air, it behaves normally.

5. What is the event horizon of a black hole? Answer: The boundary at which escape velocity exceeds the speed of light. It is not a surface you could touch, just the point past which nothing gets out.

6. How old is the universe? Answer: About 13.8 billion years, derived largely from measurements of the cosmic microwave background and the expansion rate.

7. What is the cosmic microwave background? Answer: The faint afterglow of the early universe, released about 380,000 years after the Big Bang. Penzias and Wilson found it by accident in 1964 while hunting a persistent hiss in a radio antenna.

8. What is the universe mostly made of? Answer: Not the stuff we can see. Ordinary matter accounts for roughly 5%, dark matter around 27% and dark energy about 68% — so most of the universe is something we can measure the effects of but cannot identify.

Odd Corners of Space Trivia Questions

1. What does space smell like? Answer: Astronauts returning from spacewalks describe a smell clinging to their suits like seared steak or welding fumes, probably from compounds reacting with cabin air.

2. What is Jupiter's Great Red Spot? Answer: A storm roughly the width of Earth and slowly shrinking, watched continuously by astronomers since at least 1830 and possibly far longer.

3. Does it rain diamonds on Neptune and Uranus? Answer: Quite possibly. Laboratory experiments that compress carbon-rich material to the pressures found inside those planets produce nanodiamonds, supporting models in which diamond forms deep inside and sinks.

4. Does it rain on Venus? Answer: Yes, sulphuric acid — but the surface is so hot the droplets evaporate high above the ground and never land.

5. What shape is the storm at Saturn's north pole? Answer: A hexagon — a persistent six-sided jet stream about 30,000 km (18,600 miles) across, spotted by Voyager and photographed in detail by Cassini.

6. Does the Moon have earthquakes? Answer: It has moonquakes. Seismometers left by Apollo crews recorded them, and shallow ones can ring on for more than ten minutes because the dry rock carries vibrations so well.

7. Which small moon shoots water into space? Answer: Enceladus, one of Saturn's moons, which vents plumes of water vapour and ice from fractures near its south pole. The material feeds one of Saturn's outer rings and points to an ocean beneath the crust.

8. What is on the Voyager Golden Record? Answer: Greetings in 55 languages, about 90 minutes of music from around the world, natural sounds including whale song, and encoded images, for anything that works out how to play it.

Frequently Asked Questions

What are some good space trivia questions?

The best ones set up an expectation and break it: which planet is hottest, which has a day longer than its year, why astronauts float. Each has an answer that is easy to state and hard to guess, because the intuitive answer is wrong. Myth-correcting questions work the same way, which is why the dark side of the Moon and the Great Wall appear in almost every space round.

What is the most surprising fact about space?

For most people it is that weightlessness has nothing to do with the absence of gravity. At the space station's altitude gravity is still roughly 90% as strong as on the ground; astronauts float because they are falling around Earth at about 28,000 km/h and never hitting it. Once that lands, orbital mechanics stops being mysterious.

How hot is the Sun?

The visible surface is around 5,500°C (about 9,900°F), while the core reaches roughly 15 million°C, where hydrogen fuses into helium. Stranger still, the corona above the surface reaches one to two million degrees. Why the outer atmosphere is hotter than the surface beneath it remains an open problem in solar physics.

Keep Going

Trivia is a doorway rather than a destination. A one-line answer tells you Voyager 1 left the solar system, but not what it is like to build something in 1977 and still be listening decades later. If these questions left you wanting the stories underneath, our round-up of 10 fascinating history stories takes that approach to the past, and who invented electricity untangles a question that turns out to have no single answer at all — much like most good science questions.

The gap between knowing a fact and understanding it is usually a few minutes of narrative. Chunks publishes a free five-minute narrated story daily, on iOS and Android, if you would rather have that habit built for you.