Learn Mode
Eight guided stages, each with an animation, a short explanation, hidden controls to experiment with, and a quick Check Yourself question. Move forward and back freely.
Earth Science · Earth in Space
Solar System Formation
From nebula to planets
About 4.6 billion years ago, a cold cloud of gas and dust became the Sun, the planets, and everything else in our solar system. Watch it happen in 8 steps, build your own solar system from a cloud of any size, and then test yourself.
Build Mode
Pick the mass of a gas cloud and watch it become a star with its own planets, asteroid belt, Kuiper belt and Oort cloud. Compare small, Sun-sized and giant clouds.
Test Mode
15 questions drawn from all eight stages and the build activity. No hints or feedback until the end, then you see your score, what to review, and can turn it in.
To turn in your score, sign in first with Sign in to turn in at the top of the page.
Check Yourself ↓
You finished Learn Mode!
You watched a cold nebula become a solar system. Ready to see what you remember?