Go Sun!! Biggest Solar Flare since 2005!

Evolution of the January 23, 2012 solar flare. Images, from left to right,
taken at 3:27, 3:42, and 4:13 UT. NASA Solar Dynamics Observatory

After a solar minimum that was unusually quiet and prolonged, the Sun has reawakened. Following the January 21 flare (previous post), the biggest outburst since 2005 occurred late on Sunday night, January 22, 2012, around 11:00 p.m. EST, sending a shower of charged protons toward the earth. (The flare was assigned a M8.7 intensity, and is expected to hit the earth today at 9 AM ET (plus or minus 7 hours). Here's the NASA release.

What is the difference between a solar flare and a coronal mass ejection? A solar flare is an intense burst of radiation from a sunspot as magnetic energy is released in an explosive event. It releases light at almost every wavelength of the spectrum.  A coronal mass ejection is mass released during a flare, primarily gas, often billions of tons.  CME's are sometimes associated with flares, but can also occur independently of a flare.

How are solar flares classified?
Solar flares are classified on a logarithmic scale (similar to the Richter magnitude scale), with each class having a peak flux ten times greater than the preceding one.  The flux is measured in watts per square meter (W/m**2) in a particular wavelength range (100-800 picometer X-rays) near the Earth, as measured by GEOS spacecraft. Within each class there are 9 sub-categories, each being twice as big as the previous one.  The classes are, in increasing order, A,B,C,M, and X. The flare discussed here was rated as a M8.7, just slightly below the most intense X category.

How is the effect of a flare on the earth classified?
A solar flare and CME can cause a geomagnetic storm on the earth, a disruption of our magnetosphere.
Here's a link to the classification of the effects of geomagnetic storms on earth.

Here's a link to a longer explanation.

Here, here, and here are previous posts on this blog that might be of interest.