Enhanced visual image

31

A total solar eclipse is a

lunar phenomenon. It

occurs when the moon

crosses in front of the

sun and hides its brilliant

surface. Then you can see

the sun’s extended

atmosphere. (© F. Espenak,

http://www.MrEclipse.com)

Cycles of the Moon

3

Guidepost
In the previous chapter, you studied the cycle of day and night and the cycle of the
seasons. Now you are ready to study the brightest object in the night sky. The moon
moves rapidly against the background of stars, changing its shape and occasionally
producing spectacular events called eclipses. This chapter will help you answer four
essential questions about Earth’s satellite:

Why does the moon go through phases?

What causes a lunar eclipse?

What causes a solar eclipse?

How can eclipses be predicted?

Understanding the phases of the moon and eclipses will exercise your scientifi c
imagination and help you enjoy the sight of the moon crossing the sky.
Once you have a 21st-century understanding of your world and its motion, you will
be ready to read the next chapter, in which you will see how Renaissance astronomers
analyzed what they saw in the sky, used their imaginations, and came to a revolutionary
conclusion—that Earth is a planet.