Far UV image

142

The Sun

8

This far-ultraviolet image

of the sun made from

space has been enhanced

and rendered in false

color to reveal complex

structure on the surface

and clouds of gas

trapped in arched

magnetic fi elds above

the surface. (NASA/TRACE)

Guidepost

The sun is the source of light and warmth in our solar system, so it is a natural object

of human curiosity. It is also the one star that is most clearly visible from Earth. The

interaction of light and matter, which you studied in Chapter 7, can reveal the secrets of

the sun and introduce you to the stars.

In this chapter, you will discover how the analysis of the solar spectrum can paint a

detailed picture of the sun’s atmosphere and how basic physics has solved the mystery of

the sun’s core. Here you will answer four essential questions:

What do you see when you look at the sun?

How does the sun make its energy?

What are the dark sunspots?

Why does the sun go through a cycle of activity?

Although this chapter is confi ned to the center of the solar system, it introduces

you to a star and leads your thoughts onward among the stars and galaxies that fi ll the

universe.