NASA Space Place: Studying the sun is a gas!

By Michael Gregory

National Aeronautics and Space Administration

If someone asked you to draw the sun, would you make a little yellow circle with lines coming out of it? That's fun, but what does the sun look like up close? We can see the shapes and outlines of craters and mountains on the moon, but what about the sun? Does it have rocks and dust and hills and valleys? Good question.

The sun has been a mystery for thousands of years. In the first place, no human being has ever been to the sun. It's way too hot for anyone to go near it - even a million miles away would be too close. Also, we didn't even have telescopes until around 1608. But once they started looking through them, astronomers realized that a lot was happening on our star. Dark spots appeared, moved around, and disappeared. And during solar eclipses, astronomers saw that the sun had a big, active atmosphere.

Since the space age started, our understanding of what the sun is made of and why it is so dynamic keeps growing. Using powerful space telescopes, scientists have been able to see more details than ever, details which can't be seen from the ground. In fact, NASA currently has four different missions dedicated to watching the sun.

So, the sun definitely isn't made of rocks or dust. Or lava. Or even fire. We now believe that the sun is made up of very hot gases called plasma. Why is that important? Well, plasma carries electric currents and magnetic fields as it moves around. That means that the sun is like one giant magnet! We see the surface and atmosphere of the sun moving because magnetism on the sun is constantly changing. Yes, when it comes to the sun, this is a time of exciting discovery. It won't be long before the star at the center of our solar system is ready for her close up!

We've got a whole section of the NASA Space Place web site devoted to the sun! Check out http://spaceplace.nasa.gov/menu/sun/.