THE GIANT GREEN ATMOSPHERE OF A COMET: Earlier
this month, on March 21st, Comet 252P/LINEAR buzzed Earth only 5.4
million km away. It was the 3rd-closest approach by any comet in
recorded history. Since then, amateur astronomer Michael Jäger has been
tracking the comet, taking ever-improving pictures as 252P races into
northern skies over his private observatory in Stixendorf, Austria. His
latest image, obtained on March 31st, reveals the comet's magnificent
green atmosphere:
The green cloud in Jäger's
photo comes from jets of gas spewing out of the comet's core. While the
comet's icy core is tiny, perhaps only a few km wide, the surrounding
atmosphere is enormous. The gas cloud measures 90,000 km across. This
means it is more than half the size of the planet Jupiter, and about
twice as wide as Neptune. Comet 252P/LINEAR is a gas giant, indeed.
The comet is green because its vaporizing nucleus emits diatomic carbon, C2,
a gas which glows green in the
near-vacuum of space. Astronomers who wish to see the verdant hue for
themselves can point their telescopes using this ephemeris. Mid-sized telescopes and CCD cameras are required for best results.
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