Big sunspot takes aim at Earth

Photo: The Sun with sunspots July 12, 2012. Photo by James Guilford.

Just below center-left, is AR1520, as seen from Northeastern Ohio on July 12 at 6:18 PM EDT.

Dominating the face of our Sun, this week, has been an enormous group of sunspots including those designated AR1520. The active Sun has been very interesting to watch, of late, as the dark spots rotated over the star’s limb and towards the center of its disk, facing Earth. Hydrogen-alpha observers have also been rewarded with good numbers of prominences spouting into the blackness of space. Forecasters stated AR1520 had great potential for flare activity and on Thursday, July 12, the forecast was fulfilled — just as the sunspot was aimed directly at Earth.

According to SpaceWeather.com, “Big sunspot AR1520 unleashed an X1.4-class solar flare on July 12th at 1653 UT. Because this sunspot is directly facing Earth, everything about the blast was geoeffective. For one thing, it hurled a coronal mass ejection (CME) directly toward our planet. According to a forecast track prepared by analysts at the Goddard Space Weather Lab, the CME will hit Earth on July 14th around 10:20 UT (+/- 7 hours) and could spark strong geomagnetic storms. Sky watchers should be alert for auroras this weekend.”

NASA’s orbital solar observatories, of course, captured images of the flare as it erupted. Very rarely is any individual human observer watching when the detonation occurs but one can get lucky. CAA Vice-President Mike Williams was very lucky. “I was looking at the spot {with my personal solar telescope} when it popped,” he said. “Wow what a sight!”

As so often seems the case, weather forecasts for the weekend include plenty of clouds to interfere with the view. Still, aurora fans should stay alert to active displays and the potential for clear skies; it could be a good show!

UPDATE: The CME impacted the Earth’s magnetic field at ~ 1800 UT or 2:00 PM EDT, July 14.

Photo above: The Sun with prominent AR1520 accompanied by smaller sunspots. Canon EOS 50D: ISO 400, f/11, 1/1000 sec., 400mm telephoto lens with AstroZap white light filter, 6:18 PM, July 12, 2012 — “just before the clouds rolled in,” according to photographer James Guilford.

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About Webmaster

I am Webmaster for the Cuyahoga Astronomical Association. I also participate in outreach programming in public observing and occasional presentations on behalf of the CAA and a local college.
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