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The ozone hole is something different. Ozone is important to humans because it shields us from harmful ultraviolet radiation from the Sun. The chemicals from leaky refrigerators and air conditioners make their way up in to highest part of the Earth's atmosphere. Way up there, these chemicals destroy ozone, and scientists have noticed recently that the layer of ozone in the upper atmosphere is becoming thin in some places. Scientists must study this so we can understand why it is occurring, and to take action now to protect it. It is interesting, however, that ozone is considered a pollutant when it is close to the ground. It hurts plants and trees, and our lungs. But we need it way up high to shield us from the UV.

Also, learning more about the Sun helps us to understand better other stars. And this helps us understand better the universe in which we live.

How do scientists study the Sun?
Studying the Sun and how it affects the Earth is a very complicated process. In order to successfully do this, scientists approach the problem in many different ways. They separate their scientific efforts into categories and usually specialize in specific areas, such as How the amount of light from the Sun varies over time, or How the Sun's light affects the Earth's climate.

Some scientists study the Sun using computers to predict what the Sun may do in the future. Others build special instruments which look at the Sun and make measurements; they use computers both to collect and later make sense of the measurements.

What are the aurorae?
The Aurora are colorful, whispy, moving curtains of light that occur in the night sky near one the Earth's poles. This light moves around in and changes color in a dazzling dance of light. The aurora are caused by energetic particles coming from the Sun. The Sun is very active, always putting stuff out into space. Every once in a while it can suddenly eject material -- a million tons of it -- into space. Some of this comes towards the Earth and hits our atmosphere.

The material (small particles) interacts with the Earth's outer atmosphere, causing the gas in the atmosphere to release light. This light appears in many different colors (green, blue, and red), and we call it the aurorae.

In the north they are called aurora boreallis, or northern lights. In the south they are called aurora australis, or southern lights.

What is an eclipse?
Periodically the Moon will move directly in front of the the Sun. When it does, it blocks the light coming from the Sun. If it blocks out the Sun totally, we call this a total eclipse. If the Moon only blocks part of the Sun, it is a partial eclipse. You may wish to visit a real total eclipse, observed from the South American country Chile in 1994.

During a partial eclipse, you can still see part of the Sun behind the Moon, so you must not look at it. But, if you look at shadows from the leaves in trees you'll see they appear crescent shaped. Ask your teacher to make a pinhole camera, or project an image of the Sun using a mirror, and you'll be able to see the Moon blocking the Sun.

During a total eclipse, the bright Sun is completely blocked. At this time, the outer atmosphere of the Sun, or corona, becomes visible. During this brief occurrence, you can look at the corona with your eyes, because it is a million times dimmer than the Sun. Be very careful though -- even the slightest portion of the Sun poking past the edge of the Moon can hurt your eyes!

As you may know, the Moon is much smaller than the Earth, and it cannot block the Sun from the whole Earth at once. For this reason, eclipses only affect a small portion of the Earth's surface when they occur.

By the way, during a total eclipse, the stars are also visible!