From Discover Magazine:
On August 31, the Sun threw a major tantrum. It started with a vast arc of material towering over its surface, a stream of plasma flowing between two sunspots. Sometimes these collapse back down to the Sun’s surface, but this one exploded, blasting hundreds of millions of tons of material out into space.
SDO captured this ridiculously awesome picture of the arc just before it erupted:
Holy solar hissy fit! [Click to enfilamentenate.]
This picture is a combination of two images, both in the extreme ultraviolet part of the spectrum (30.4 and 17.1 nanometers, to be specific), where magnetic activity is easy to spot. The bright spot to the upper left is a sunspot, which are normally dark in optical light, but shine brightly in the UV. The filament, as the arch is called, is so big it’s
hard to comprehend: it was something like 300,000 kilometers (nearly 200,000 miles) across! That’s nearly enough to extend from the Earth to the Moon.
Images credit: NASA/GSFC/SDO; Stephen Ramsden