Reported September 2006

BACKGROUND: The sun is continuing to produce very large sunspots, more than four years after "solar maximum" in the sunspot cycle, which typically recurs over 11 years. There is a sunspot currently transiting the solar disk that is about five times wider than Earth, big enough to view with the unaided eye.

ABOUT THE SUN: The sun is a star, and like most stars, it's composed of hot gases: almost 75 percent hydrogen and 25 percent helium, with less than 1 percent being made up of oxygen and other elements. The source of the sun's energy is nuclear fusion. The nuclei of hydrogen atoms -- the simplest atoms, with one proton and one electron -- heat to such high temperatures (15,000,000 degrees Celsius) that they fuse together into helium nuclei -- with two protons and two electrons. In the process, they lose a small amount of mass, which is transformed into energy. Although the sun loses half a million tons every second, it will continue to shine for about 5 billion years. Once all the hydrogen in the sun's core is converted into helium, the core will contract and become even hotter, while the outer part will expand and become cooler -- it will become a red giant star. Eventually all sources of energy production will be consumed and the sun will collapse into a very small, hot object called a white dwarf.

SUNSPOTS AND SOLAR FLARES: Sunspots are temporary features on the surface of sun, regions that are somewhat cooler that the surrounding surface area, so they appear darker. Astronomers believe that sunspots are basically whirlwinds of electrified matter that burst out from inside the sun. The number of sunspots rises and falls, and corresponds to the number of solar flares: bursts of intense radiation that eject streams of electrically charged particles. An increase in flares leads to an increase in sunspots, and the same goes for any decreases. Sunspots can cause electrical effects in the earth's atmosphere, such as the Northern Lights.

STARING AT THE SUN: It is extremely dangerous to stare directly at the sun with the naked eye, or even with binoculars or telescopes using unfiltered lenses, since the radiation will seriously damage the eyes and result in partial or total blindness. But it is possible to safely observe solar phenomena like sunspots or eclipses by taking reasonable precautions. For instance, you can project an image of the sun through a telescope or binoculars onto some sort of white screen, like a paper plate or a wall. A bright circle of light will show up on the screen. The image will probably be blurry, but you can focus the telescope to sharpen the circle so that you can see details in and around sunspot groups. You can also use pinhole projectors or solar filters to safely view the sun.

The American Astronomical Society contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

Brad Schaefer, Ph.D.
Dept. of Physics and Astronomy
Louisiana State University
Baton Rouge, LA 70803
(225) 578-0015
schaefer@lsu.edu

SOHO Sunspots

American Astronomical Society
Washington, DC 20009-1231
(202) 328-2010
aas@aas.org
http://www.aas.org

FACTOID...

Sunspots have been directly observed since 350 B.C., and were first observed through a telescope by Galileo in 1610 A.D.

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Safe Sunwatching