Rings & the Roche Limit

Torn apart by tides

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Tidal forces tear apart loosely bound bodies inside the Roche limit.
• Roche limit $\approx 2.44 R (\rho_p/\rho_m)^{1/3}$ for a fluid moon.
• Planetary rings lie close in, around or inside the Roche limit.

Steps

1. Too close for comfort
2. Saturn’s rings
3. Our Moon
4. A comet’s fate
5. Saturn’s danger zone
6. The end of Phobos