Space Trivia Questions and Answers

Planets, moons, stars and the light that travels between them: these space trivia questions tour our solar system and beyond. Some are easy wins, others are record-breakers that surprise even astronomy fans. Each answer comes with a short explanation and a fun fact to take away.

8 questions · Every answer explained · Fact-checked October 2026

1. 1. What is the closest star to Earth?

   • A. Proxima Centauri
   • B. Sirius
   • C. The Sun
   • D. Polaris
   Show answer

   C. The Sun — The Sun is a star, about 150 million km away; the next nearest, Proxima Centauri, is over 4 light-years away.

   Did you know? Sunlight takes about eight minutes to reach us, but Proxima's light takes more than four years.

2. 2. How many planets are in our solar system?

   • A. 7
   • B. 8
   • C. 9
   • D. 10
   Show answer

   B. 8 — There are eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

   Did you know? Pluto was counted as the ninth until 2006, when it was reclassified as a dwarf planet.

3. 3. What is the largest planet in our solar system?

   • A. Saturn
   • B. Neptune
   • C. Earth
   • D. Jupiter
   Show answer

   D. Jupiter — Jupiter is a gas giant more than 11 times wider than Earth.

   Did you know? All the other planets could fit inside Jupiter with room to spare.

4. 4. Which planet spins on its side, with an axial tilt of about 98 degrees?

   • A. Neptune
   • B. Uranus
   • C. Saturn
   • D. Mars
   Show answer

   B. Uranus — Uranus is tipped so far over that it effectively rolls around the Sun, probably after an ancient giant collision.

   Did you know? Each of Uranus's poles gets about 42 years of continuous sunlight, then 42 years of darkness.

5. 5. About how long does sunlight take to reach Earth?

   • A. 8 seconds
   • B. 8 minutes
   • C. 8 hours
   • D. 8 days
   Show answer

   B. 8 minutes — Crossing about 150 million km at light speed takes roughly 8 minutes and 20 seconds.

   Did you know? So when you look at the Sun, you're seeing it as it was over eight minutes ago.

6. 6. Which is the hottest planet in our solar system?

   • A. Mercury
   • B. Venus
   • C. Mars
   • D. Jupiter
   Show answer

   B. Venus — Venus's thick carbon dioxide atmosphere traps heat, keeping its surface around 465 °C — hotter than Mercury, despite being farther from the Sun.

   Did you know? Venus is hot enough to melt lead, day and night.

7. 7. What is the largest moon in our solar system?

   • A. Titan
   • B. Ganymede
   • C. Callisto
   • D. Europa
   Show answer

   B. Ganymede — Jupiter's Ganymede is about 5,270 km across — larger than the planet Mercury.

   Did you know? It's the only moon known to have its own magnetic field.

8. 8. What will the Sun become at the very end of its life?

   • A. A black hole
   • B. A neutron star
   • C. A white dwarf
   • D. A supernova
   Show answer

   C. A white dwarf — The Sun isn't massive enough to explode; after a red-giant phase it will shed its outer layers and leave a white dwarf.

   Did you know? That's billions of years away — the Sun is only about halfway through its life.