Our Stormy Sun

H-alpha Sun
The Sun in the red light of the hydrogen atom on Tuesday, July 23rd, showing numerous prominences jutting from the limb. This composite of two exposures was made through a Coronado SolarMax 40 H-alpha filter. Celestial north is toward upper left. Active region 10030 is on the disk at upper right, while 10039 is at bottom.
S&T photo by Rick Fienberg.
The current solar-activity cycle peaked in May 2000, but someone apparently forgot to tell the Sun. As one giant sunspot complex prepares to rotate off our star's face, another has already swung into view. Both are currently visible to the unaided eye and are nothing short of spectacular in a telescope — provided you use safe solar filters, of course.

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Last week Sunwatchers kept an eye on the active region designated 10030 by the U.S. National Oceanic and Atmospheric Administration (NOAA). This complex flared repeatedly as it crossed the solar disk. It was (and still is) one of the largest spot groups in recent years. But active region 10039, which has now rotated into full view, looks like it may be even more stormy.

The sunspot complex corresponding to active region 10039 swings into view on the Sun's limb on July 23rd. This white-light view was obtained with a Questar 3.5-inch telescope, Baader AstroSolar filter, and Nikon digital camera.
S&T photo by Dennis di Cicco.

Even before this second sunspot complex became visible, astronomers suspected it packed a strong punch, because they detected ionized gas leaping up thousands of miles from behind the Sun's limb. Yesterday the newly visible spot group produced a spectacularly powerful ("X-class") flare. With the Moon now waning and out of the evening sky, there's a good chance observers at middle latitudes may catch a rare auroral display before bedtime one night soon.

"The next two weeks may see more 'fire in the sky' than we have in the last 10 years," says Cary Oler (Solar Terrestrial Dispatch), "if the spot complex continues to pump out activity at the furious rate that it is presumed to have produced over the last week."

Richard Tresch Fienberg

About Richard Tresch Fienberg

Professional astronomer by training and Sky & Telescope's former editor in chief, Rick Fienberg is now press officer at the American Astronomical Society and an advocate for astronomy outreach.
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