charles 2009-3-27 10:52
地平線上的彗巴
A Comet Tail Horizon
[img]http://i5.tinypic.com/3yzjpsw.jpg[/img]
影像提供與版權: Marco Fulle (Stromboli online)
[color=navy]Explanation: [/color]
[color=dimgray]What's happening over the horizon? Many a sky enthusiast who thought they had seen it all had never seen anything like this. To the surprise of many Northern Hemisphere observers, the tail of Comet McNaught remained visible even after the comet's head set ahead of the Sun. What's more, visible were bright but extremely rare filamentary striae from the comet's expansive dust tail. The cause of dust tail striae are not known for sure, but are possibly related to fragmentation of comet's nucleus. The last comet to show prominent striae was Comet Hale-Bopp in 1997. Pictured above, the tail of Comet McNaught was caught just after sunset above the Carnic Alps of northern Italy.[/color]
[color=navy]說明:[/color]
[color=dimgray]地平線上是什麼東西？許多的天文愛好者從來沒看過像這樣的景像。讓北半球的觀測者驚奇的是，麥克諾特彗星雖然在日落前就下山，但日落後仍然可以看到它的彗尾。更甚者，你可以很清楚地看到彗尾展開並呈現難得一見的絲狀條紋。雖然天文學家對這種彗尾結構的成因還不是很確定，但極有可能是由於彗核的分裂所造成的。上一顆有明顯彗尾大彗星是1997年的海爾-波普彗星(Comet Hale-Bopp)。上圖是日落後，在義大利的卡爾尼克阿爾卑斯山 (Carnic Alps)所拍攝到麥克諾特彗星的彗尾。
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[size=2]資料來源: Scientific American
Department of Physics, NCKU[/size][color=white][size=1]
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