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Scale Detective

Which celestial body has more? Compare size, moons, gravity, temperature, and more across our solar system.

How to play

  • Two bodies appear — pick which has MORE of the property shown
  • 20 questions, 5 seconds each
  • 1 point per correct answer, max score 20

About Scale Detective

Which is bigger, Mars or Mercury? Which moon pulls harder — Titan or our own Moon? Human intuition is bad at this, since nothing in everyday life prepares you to compare objects that range from a small moon to a gas giant thousands of times its volume. This fast-paced quiz pits real planets, moons, and dwarf planets against each other on size and gravity, using actual NASA measurements for every comparison.

The surprises are the point — Jupiter's moon Ganymede is bigger than Mercury, and Saturn is less dense than water. Getting those wrong once tends to make them stick the second time.

Keep Exploring

More on the real scale of the solar system