Red sky at night ... astronaut's delight

Alan Boyle writes

"Red sky at night, sailor's delight": That's one of the oldest sayings in the book when it comes to weather prediction, but this picture adds a new twist. The red sky is an aurora, seen from above by astronauts on the International Space Station. And the weather that's causing this phenomenon is space weather from the sun.

Auroras arise when electrically charged particles from the sun interact with atoms in the upper atmosphere, sparking emissions of light at various wavelengths. The displays are most likely to be visible around Earth's magnetic poles, where the interaction is strongest. The sun has been going through an upswing of activity over the past couple of months, which has generated a colorful series of northern and southern lights.

North or south, the most common shade of auroral light is green. That's the wavelength that's typically emitted when solar particles mix it up with oxygen atoms. But if there are lower-energy collisions with oxygen atoms or nitrogen atoms, the emissions edge toward the reddish end of the spectrum. That's what's happening in this picture, captured on Monday. You should be able to make out the space station's solar panels toward the upper left corner of the photo.

Space weather can create disruptions for satellite communication systems as well as electric grids on Earth, but so far the most noticeable effect from this year's solar storms has been a string of glorious auroras. We weathered the latest geomagnetic storm overnight, and SpaceWeather.com is offering up a selection of snapshots ? including this red-and-green stunner from Russia's Kola Peninsula.

To learn more about the colors of the aurora, check out this "Causes of Color" explanation. And if you live in northern or southern climes, there's always a chance of seeing the lights for yourself. Last night, the aurora was visible from Minnesota, Germany and Poland in the north, as well as New Zealand in the south. The University of Alaska at Fairbanks provides this handy-dandy online guide to aurora-watching.

More auroral glories:

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Source: http://photoblog.msnbc.msn.com/_news/2011/09/27/7997049-red-sky-at-night-astronauts-delight

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