August 2, 2010

Have you ever seen the Northern Lights, formally known as the Aurora Borealis, leap in the northern sky? The French scientist Pierre Gassendi gave this phenomenon its name in 1621, combining the name of the Roman goddess of dawn, Aurora, with the Greek name for the north wind, Boreas.

You never know exactly when the Aurora Borealis is going to be visible because these spectacular light shows are the result of space weather - including the eruption of solar flares. Early yesterday morning (August 1), NASA’s Solar Dynamics Observatory recorded what they called "a complex global disturbance involving almost the entire Earth-facing side of the sun."  The event included a long-duration C3-class solar flare, what called a "solar tsunami."

These blasts have created a coronal mass ejection (CME) that is heading toward Earth.  It may be possible, especially in northern latitudes, to see the Northern Lights when the cloud arrives. It takes two days for the "solar wind" to reach Earth, so tomorrow night is the time to look to the northern skies.  

We have been in a quiet period since 2007, with little solar activity dramatic enough to cause auroras. Readers in the Northern Hemisphere, particularly those at higher latitudes, I hope we’ll break the streak and see a great show this week!

If you’re interested in learning more about this topic, the Geophysical Institute at the University of Alaska/Fairbanks has an excellent FAQ page with many photographs of auroras, as well as diagrams showing clearly how they occur, and why.



Posted by: Seymour Simon

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