Watching the Sunsets
The surface of the Sun looks like a pot of boiling water, with millions of bubbles of hot gas carrying energy to its surface. But each of these bubbles -- called granules -- is bigger than Texas.
Astronomers suspect that the character of the granules changes over the course of the Sun's 11-year magnetic cycle. Astronomers at McDonald Observatory are looking for this change -- not by looking at the Sun itself, but by watching the beautiful West Texas sunsets.
The astronomers are using the giant Hobby-Eberly Telescope. Looking at the Sun directly would fry the telescope's electronics. But the light we see in the sky during the day is simply sunlight reflecting off of material in the atmosphere. So the astronomers are aiming the HET at the southern sky at sunset.
They use an instrument called a spectrograph to break the sunlight into its component wavelengths or colors. From this, astronomers can tell how bright the granules at the Sun's surface are, and how fast they're rising toward the surface.
During the Sun's magnetic cycle, dark sunspots appear on its surface, and flares of energy explode into space. Astronomers suspect that the change in the Sun's magnetic field may affect the pattern of the granules -- their size, motion, and temperature. By studying the granules as the Sun goes through this magnetic cycle, the Texas astronomers hope to find out if that's really the case -- just by watching the sunset.
Script by Damond Benningfield, Copyright 2004
For more skywatching tips, astronomy news, and much more, read StarDate magazine.
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