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.)
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
發表於 2009-7-28 00:25:04
發表於 2009-7-28 17:01:44