Solar Flare of April 16, 2012
May 06, 2012
Photographer: John Stetson
Summary Author: John Stetson
The M-class solar flare of April 16, 2012 (highlighted in the box at upper left) was a most amazing event. When aimed toward Earth flares such as this can seriously disrupt power grids and global communications once they hit our magnetosphere. However, when seen on the limb of the solar disk as this one is, they're aimed elsewhere and are more awe-inspiring than disruptive.
For purposes of perspective, the image shown above has been inserted into a full-disk inverted image of the Sun taken on April 13. Approximately 109 Earths would fit across the Sun's angular diameter (0.5 degree). In about 25 minutes of elapsed time, this flare extended out a distance of nearly 40 Earths from the Sun's limb. So, about 317,160 mi (510,419 km) was covered in 25 minutes. This translates into an estimated 761,184 mph (1,225,007 km/h). Initial flare activity was observed at 17:45 UT; time of the "snapshot" image showing the extent of the flare was 18:10 UT. For comparison, the speed of light is 670,616,629 mph (1,079,252,850 km/h).