What Is an Eclipse? :

An eclipse occurs when a celestial object passes in front of another object and blocks some of its light. There are two main types of eclipses that involve the Moon, the Sun, and Earth.

Sometimes the Moon blocks the light from the Sun and part of Earth is in the Moon’s shadow. The word solar refers to the Sun. During a solar eclipse, the Sun is blocked.

The word lunar refers to the Moon. During a lunar eclipse, the Moon is blocked: Earth blocks the Sun’s light from reaching the Moon and the Moon is in Earth’s shadow.

In this lesson, you will explore how the motions and positions of the Moon, the Sun, and Earth produce eclipses, and investigate how often they happen.

Watch this video for an introduction to lunar and solar eclipses.

Keyboard Shortcut	Action
Space	Pause/Play video playback
Enter	Pause/Play video playback
m	Mute/Unmute video volume
Up and Down arrows	Increase and decrease volume by 10%
Right and Left arrows	Seek forward or backward by 5 seconds
0-9	Fast seek to x% of the video.
f	Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key.
c	Press c to toggle captions on or off