The Restless Sun

The sun is near the minimum of its current sunspot cycle, yet a number of major solar events have occurred. A month after the Solar and Heliospheric Observatory (SOHO) captured images of its 1,000th comet, the spacecraft imaged a huge coronal mass ejection emerging from the side of the sun. The mass eruption was associated with sunspot region 798. Two days later, that region was the source of a gigantic X-17 solar flare, the fifth largest solar flare recorded.

The SOHO team predicted that the activity from region 798 would enhance aurora displays on Earth, and it certainly did. A few days later people as far south as Arizona reported seeing an aurora display.

The sun completes a rotation in about 28 days, a parameter that can be easily measured by an amateur equipped with a very simple apparatus that projects the image of the solar disk onto a sheet of white paper. Sun spots are marked on the paper, and the sun is checked on successive days to see how the spots apparently move across the face of the sun. The movement is only relative, however, for the sun spots are stationary and the sun itself is rotating.

WARNING: Never attempt to observe sunspots by looking at the sun directly or through binoculars or a telescope! Safe directions for solar observing are found at various web sites and on the "The Amateur Scientist 2.0 CD-ROM" (see "Sunspots and How to Observe Them Safely," June 1990).

Solar flares can be detected by a Geiger counter, a method used by Vicki R. Mims to detect a dozen X-class solar flares when she was a high school student.

SOHO is a joint space mission to observe the sun conducted by the European Space Agency (ESA) and NASA.

Forrest M. Mims III