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Impressive crater chain in Ganymede

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發表於 2009-7-28 00:25:04 | 顯示全部樓層 |閱讀模式
On July 19, the Hubble Space Telescope captured a sharp atmospheric scar on Jupiter which was thought to form from a comet or asteroid that collided with the planet.

I recall an old picture too showing an impressive “crater chain” on Jupiter’s satellite Ganymede. It was created probably from a comet which was pulled into pieces by Jupiter's gravity as it passed too close to the planet. See this crater chain from
http://neo.jpl.nasa.gov/images/ganymede.html  or
http://apod.nasa.gov/apod/ap011215.html

Crater chains exist on the Moon too, see this example (named Catena Davy) on:

(A C8 amateur telescope can see this catena.)

AC
 樓主| 發表於 2009-7-28 01:04:55 | 顯示全部樓層

What is a “rubble-pile”

An asteroid is easily disrupted if it is in rubble pile (碎石堆) form.

Rubble Pile  refers to a weak aggregate of large and small debris held together by gravity rather than material strength. A good example is illustrated by near-Earth asteroid “Itokawa” explored by the Japanese Hayabusa spacecraft in 2005, shown in
http://en.wikipedia.org/wiki/25143_Itokawa   

or more specific in
http://www.isas.jaxa.jp/j/snews/2005/1101_hayabusa.shtml

AC

[ 本帖最後由 mca 於 2009-7-28 01:08 編輯 ]
發表於 2009-7-28 17:01:44 | 顯示全部樓層

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Davy's chain is a lovely sight and I enjoy watching it every time when it is well illuminated.
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