How Fast Can a Planet Spin?

The spin barrier

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

• A spinning body flies apart at the equator if $\omega^2R > GM/R^2$.
• Minimum period $T_{\min} = \sqrt{3\pi/(G\rho)}$, set by density alone.
• Rubble-pile asteroids hit a 2.2-hour spin barrier; pulsars must be neutron stars.

Steps

1. Gravity versus spin
2. Earth today
3. Spin up the Earth
4. The bulge
5. The asteroid spin barrier
6. Millisecond pulsars