<p dir="ltr"><strong>Bullseye! A bright flare erupts from the sun's surface as seen straight-on by <a href="http://sdo.gsfc.nasa.gov/">NASA's Solar Dynamics Observatory</a> (SDO) spacecraft.</strong></p><p><strong></strong></p><p dir="ltr">Solar flares release strong radiation outbursts, ones sometimes strong enough to interfere with radio signals on Earth. This October 23 outburst clocked in near the top of the "medium" class of such flares, making it an <a href="http://www.nasa.gov/content/goddard/sdo-sees-sun-emit-mid-level-solar-flare/#.UmqTWZTSOhA">M9.4-class solar flare</a>. (Related: <a href="http://news.nationalgeographic.com/news/2012/03/120308-solar-flare-storm-sun-space-weather-science-aurora/">"Solar Flare: What If Biggest Known Sun Storm Hit Today?"</a>)</p><p><strong></strong></p><p dir="ltr">Such flares have become more common with the sun now near the peak of its regular sunspot activity cycle.</p><p><strong></strong></p><p dir="ltr">SDO watches for such outbursts in the ultraviolet spectrum, as seen here, to see details of flares washed out or unseen in visible-light images. (Related: <a href="http://news.nationalgeographic.com/news/2011/06/110608-solar-flare-sun-science-space/">"Solar Flare Sparks Biggest Eruption Ever Seen on Sun."</a>)</p><p dir="ltr"><em>—Dan Vergano</em></p>