Early Tuesday morning (August 9, 2011,) the Sun erupted with the largest solar flare of Cycle 24, registering as an X7-class flare. This flare had an X-ray magnitude of X6.9, meaning it was more than 3 times larger than the previous largest flare of this solar cycle – the X2.2 that occurred on Feb 15, 2011, NASA said. The source was Sunspot 1263 which is nearing the western limb of the Sun, and because of its location, scientists do not anticipate that this explosion will hit Earth directly. Therefore, the impact on communications and electric grids will likely (and luckily) be minimal.
A solar flare is an explosion on the Sun that happens when energy stored in twisted magnetic fields –usually above sunspots — is suddenly released. Flares produce a burst of radiation across the electromagnetic spectrum, from radio waves to x-rays and gamma-rays.
Solar flares are classified according to their x-ray brightness, and there are 3 categories: X-class flares are big and are major events that can trigger planet-wide radio blackouts and long-lasting radiation storms. M-class flares are medium-sized; they can cause brief radio blackouts that affect Earth’s polar regions. Minor radiation storms sometimes follow an M-class flare. Compared to X- and M-class events, C-class flares are small with little noticeable impact on Earth.
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Nancy Atkinson is currently Universe Today’s Contributing Editor. Previously she served as UT’s Senior Editor and lead writer, and has worked with Astronomy Cast and 365 Days of Astronomy. Nancy is the author of the new book “Incredible Stories from Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos.” She is also a NASA/JPL Solar System Ambassador.