Home > Subscriber extras > Ask Astro
Ask Astro
What is the speed of the Moon's terminator?

The terminator is the line separating day from night on a planet or moon. As the changing angles between Sun, Moon, and Earth alter the parts of the Moon bathed in daylight, the lunar terminator sweeps across the Moon's surface. This creates the familiar cycle of lunar phases.

Subscriber Only Content
You are not currently logged in. To view this page you must be a subscriber to Astronomy magazine.
Already a subscriber?
Not a subscriber?
Current Issue
Subscribe today and get 12 issues of Astronomy magazine plus these great online subscriber-only benefits:
  • An Interactive Atlas of the Stars
  • Star Dome PLUS
  • Multimedia Gallery
  • The sky this month
  • And much more!
E-mail Address: Password:
Remember me?

Forgot your password » | Login help »

Not a member? Register » | Why join? »

Newsletter Signup

Receive news, sky-event information, observing tips, and more from Astronomy's free weekly e-mail newsletter.

Privacy Policy

Atlas of the Stars: New Edition