Labs / Astronomy
Tidal Locking
A moon circles its planet while spinning on its own axis. Slide the spin rate and watch the amber surface marker: when the moon turns exactly once per orbit, the same face stays aimed at the planet forever — that is tidal locking. Drag the moon around its orbit to inspect any moment for yourself.
spin:orbit 1.00 : 1drift/orbit +0°face offset +0°status Locked
What to try
- Set the spin to exactly 1× the orbit rate. Why does the marker never leave the planet-facing side?
- Turn off the spin entirely. If the moon does not rotate at all, why does every part of its surface still take a turn facing the planet?
- Try Mercury's 3:2 spin. How far does the near point drift each orbit, and how many orbits pass before the same face returns to the planet?
- Watch the tidal bulge. Which way does it lag when the moon spins too fast, and how could that lag act like a brake on the spin?
- Nudge the spin just above or below 1×. How slowly does the “face offset” creep — and is that near-locked state close enough to call it locked?