mariah 2009-3-24 14:38
紅外線波段的自轉泰坦衛星
Rotating Titan in Infrared Light
[img]http://www.apodaustralia.com/apod/image/0602/titanrotating_cassini_big.gif[/img]
影像提供: VIMS Team, U. Arizona, ESA, NASA
[color=navy]Explanation: [/color]
[color=dimgray]Titan is one of the strangest places in our Solar System. The only moon known with thick clouds, this unusual satellite of Saturn shows evidence of evaporating lakes created by methane rain. The clouds that make Titan featureless in visible light have now been pierced several times in infrared light by the robot Cassini spacecraft currently orbiting Saturn. These images have been compiled into the above time-lapse movie. Like Earth's Moon, Titan always shows the same face toward its central planet. It therefore takes Titan about 16 days to complete one rotation. Titan has numerous areas of light terrain with some large areas of dark terrain visible near the equator. Small areas of brightest terrain might arise from ice-volcanoes and have a high amount of reflective frozen water-ice. Titan's surface was imaged for the first time early last year by the Huygens probe, which survived for three hours on a cold and sandy dark region. [/color]
[color=navy]說明:[/color]
[color=dimgray]泰坦衛星是我們太陽系最怪異的天體之一，它是唯一具有厚重大氣的衛星，而且有相當的證據顯示這顆不尋常的土星衛星曾有許多甲烷雨所造成的乾涸湖泊。為了要穿透在可見光波段遮掩泰坦特徵的雲層，正在繞行土星的卡西尼號太空船數次在紅外光波段拍攝泰坦衛星，這些影像被集結成上面這個時序動畫電影。和地球的月亮相似，泰坦衛星永遠以同一面對了中央行星，因此要拍攝一個完整的自轉得用上十六天。泰坦衛星有許多淡色平野，而赤道附近則有大面積的暗色區域。有些很明亮的小範圍區塊可能有大量高反射率的水冰，它們可能是由冰火山所造成的。在去年，惠更斯探測器首次為泰坦衛星表面造影，它在表面冰冷多砂的暗色區域存活了三小時。[/color]
[size=2]資料來源: Scientific American
Department of Physics, NCKU[/size][color=white][size=1]
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