5-Second Quiz: Space
Planets, moons and missions — ten questions, five seconds each.
10 questions · 5 seconds each · 3 easy, 4 medium, 3 hard
Faster right answers score more. Running out of time counts as wrong.
Every answer here comes from NASA or ESA: the hottest planet, the moon with a real atmosphere, the telescope that launched on Christmas Day, the year Pluto stopped being a planet. Nothing that shifts from year to year — no moon counts, no exoplanet tallies.
Each round draws 10 of the 40 questions — three easy, four medium, three hard. The wrong answers are always neighbours: another planet, another moon, a number of the same size, a mission from the same era. Close enough to cost you the second you don't have.
Grades
- 0–39 ptsStargazer — You know which way is up. The rest of the sky is still waiting.
- 40–59 ptsSpace Cadet — A solid cadet — the planets you know cold, the moons not quite yet.
- 60–79 ptsAstronaut — Astronaut level. Only the numbers and the far-out missions slowed you down.
- 80–100 ptsAstrophysicist — Astrophysicist. You answered faster than moonlight reaches Earth.
Two sample questions
Which planet is the hottest in our solar system?
- Mars
- Venus
- Jupiter
- Mercury
Show the answer
Venus — Venus's thick atmosphere traps heat, so it beats Mercury even though Mercury is closer to the Sun. Source
What is the largest moon in our solar system?
- Europa
- Callisto
- Titan
- Ganymede
Show the answer
Ganymede — Jupiter's moon Ganymede is bigger than the planet Mercury. Source
How scoring works
A right answer is worth 1 point plus up to 0.5 for speed — the more of the 5 seconds you have left, the bigger the bonus. Wrong answers and timeouts score nothing. The total is scaled to 100.
Ten right answers at about 2.5 seconds each lands just above 80 — the top grade. Nine right needs real speed to get there.
“Top %” is an estimate, not a leaderboard. It models players of different skill answering easy, medium and hard questions (about 76%, 54% and 33% right overall) in 1 to 5 seconds, and shows the share who would score at least as high as you. No one's results are stored.
Frequently asked questions
Does this quiz count Pluto as a planet?
No. It follows the International Astronomical Union, which reclassified Pluto as a dwarf planet in 2006 — and one of the questions is about exactly that.
Why are there no questions about how many moons a planet has?
Moon counts keep rising as telescopes find new ones, so any number would go stale. The questions stick to what stays true: sizes, temperatures, firsts and mission dates.
Where do the space answers come from?
NASA's planet and mission pages, JPL and ESA. Each answer on your own result links to the page it was checked against.