An eclipse occurs when the moon or the earth casts its shadow on the other.

Cause: [Go to  What Causes an Eclipse?]

Moon's orbit is nearly in line (varying about 5 degrees) with earth's orbit,

So each occasionally gets between the other and the sun.

Terms:

Umbra - the darkest portion of the shadow (all shadow)

Penumbra - the lighter edges, a "partial" shadow,

e.g., for a partial lunar eclipse:

- The moon is in Earth's penumbra, or only partially in the umbra and partially in the penumbra.

During which the moon moves in-between
the Earth and the Sun

Observing Eclipses Safely
Adapted from Chapter 11 - Totality: Eclipses of the Sun
Copyright ©1999 by Mark Littmann, Ken Willcox and Fred Espenak - "Mr. Eclipse"

Total, Partial and Annular Eclipse Animations and Tutorial From Ted Froberg's Eclipse Site

Solar Eclipses for Beginners - from "Mr. Eclipse"

Various stages of the annular solar eclipse 1994 May 10.  © Fred Espenak MrEclipse.com

Lunar Eclipses           

During which the Moon moves into Earth's shadow

See A Lunar Eclipse Diagram

Lunar Eclipse Photo Gallery - from "Mr. Eclipse"

Go Back to Astronomy Class Syllabus

Go On to Earth's Moon

Go Back to Sun/Earth/Moon System

Go Back to Moon Notes

Updated 03/03/08