THE NEXT STREAM OF SOLAR WIND: Earth is passing through a void between streams of solar wind. The next stream lies ahead. Estimated time of arrival: Aug. 20-21. The gaseous material is flowing from a southern hole in the sun's atmosphere. Its grazing impact could spark geomagnetic activity just below the level of a G1-class storm. Aurora alerts: SMS Text.
WHY ARE SO MANY METEORS GREEN? The Moon is not made of green cheese. Neither are meteors. But if that's true, why are so many meteors green? During the recent Perseid meteor shower, sky watchers witnessed hundreds of green meteors. Take a look at this fireball. And this one. And this one. And, last but not least, this one:
"This green Perseid cut right through the Double Cluster (h Persei and χ Persei) in Perseus," says photographer David Blanchard of Flagstaff, Arizona, who caught the verdant streak during a 30 second exposure with his Nikon digital camera.
The source of the green is not cheese, it's air. Green is caused by oxygen in Earth's atmosphere. When a meteoroid rips through the atmosphere, air in its path becomes so hot that oxygen molecules briefly lose one of their electrons. They recombine (e- + O2+) very rapidly, emitting green photons as a side-effect. A similar process is responsible for the green colors of many auroras.
Blanchard's meteor has a fringe of yellow alongside the green. Yellow, it turns out, is due to the meteor. When a sodium-rich meteoroid cuts through the atmosphere, hot sodium vapors glow yellow like a sodium discharge lamp.
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APOLLO 11 PROOF SILVER DOLLARS: The students of Earth to Sky Calculus weren't even born when Neil Armstrong and Buzz Aldrin landed on the Moon in 1969 years ago. Nevertheless, they "get it." On July 20th, the students launched 50 Apollo 11 silver dollars to the stratosphere onboard a cosmic ray balloon. The coins touched the edge of space 50 years to the day after Neil and Buzz made footprints in the Sea of Tranquillity:
You can have one for $197.95. The students are selling these coins to support their cosmic ray ballooning program. Quantities are limited and more than half have already been sold. Each one comes with a greeting card showing the item in flight and telling the story of its journey to the edge of space.
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