Explore the Solar System
Tap any body for NASA fact-sheet data — diameter, gravity, day/year, atmosphere and a notable mission.
All bodies
Major Moons
More than 40 named natural satellites grouped by parent body. Earth has one. Saturn alone hosts 146 confirmed moons; the most pedagogically important are listed.
Orbital Animation
Watch the planets orbit at their real period ratios. Mercury laps Earth roughly four times per year; Neptune takes 165 years per loop.
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True Scale Visualizer
Most diagrams cheat on either size or distance. Try both side by side.
Diameter scale
Drag the slider to set Earth's radius in pixels. Every other body is drawn at the same proportional scale — the Sun gets enormous fast.
Distance scale
If the Sun were the size of a basketball (24 cm), here is how far apart everything would be on the same scale. Walk it.
A scale model where the Sun is a basketball puts Neptune nearly a kilometer away — and the nearest star, Proxima Centauri, more than 6,400 km off. The solar system is mostly empty space.
Drill
Four modes — identify a body from a clue, order by size, match a moon to its parent, or recall a key fact.
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Mystery Body
Three progressive clues. Guess at any time.
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Mystery #1
Daily Challenge
Eight questions. One set per day, the same for everyone. New set at midnight local time.
Today's set
Question 1 / 8