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Large sunspot group AR 2339

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May 10, 2015

View larger. | Photo taken May 7, 2015 by Alan Friedman. — View larger. | AR 2339. Photo taken May 7, 2015 by Alan Friedman.

The current solar cycle – Cycle 24, which peaked last year – has been the weakest solar cycle recorded in over a century. During very active solar cycle peaks, the sun’s surface might be blemished with dozens or even hundreds of spots. Not so with the peak of this cycle, and, although we should still be seeing a large number of sunspots as this cycle goes into its decline, there was a day in late April when the sun showed no visible spots at all. So astronomers were glad to see this large sunspot region rotate into view on May 5. It quickly grew to a size many times larger than Earth.

Astronomers call this sunspot grouping AR 2339.

Earth compared to sunspot group AR 2339. Image via SkyandTelescope.com

Just as it was coming into view, AR 2339 released a powerful X2-class solar flare.

That flare was associated with a coronal mass ejection (CME); however, the CME was not Earth-directed. Hence, no super auroral display, at least not caused by this sunspot grouping.

But that could still happen, with AR 2339!

View larger. | C.B. Devgun in New Delhi, India captured AR 2339 at sunset today (May 10, 2015). — View larger. | C.B. Devgun in New Delhi, India submitted this photo of AR 2339 to EarthSky today (May 10, 2015). It’s AR 2339 at sunset.

Abhijit Juvekar in India captured this photo earlier today - May 10, 2015. Thank you, Abhijit! — EarthSky Facebook friend Abhijit Juvekar in India captured this photo earlier today – May 10, 2015. Thank you, Abhijit!

AR 2339. Photo taken May 8, 2015 by EarthSky Facebook friend Brodin Alain.

Bottom line: AR 2339 – a sunspot group many times larger than Earth – rotated into view on the sun on May 5, after a period of quiescence on the sun. It immediately produced an X-flare!

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May 10, 2015

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Deborah Byrd

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Deborah Byrd (asteroid 3505 Byrd) helps edit EarthSky.org and is a frequent host of EarthSky videos. Deborah created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Prior to that, she had worked for the University of Texas McDonald Observatory since 1976, and created and produced their Star Date radio series. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named in her honor in 1990, a Public Service Award from the National Science Board in 2003, and the Education Prize from the American Astronomical Society in 2020. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.