Relationship of indentations and age of object.

[Frank]

The asteroid or satellite shown in the latest photograph shows a lot of pock marks or craters. The commentator said it was a very old object b ecause of these indentations.
My question is whether scientists can tell how old an object is from looking at it and inspecting the number of "hits". Is this an emperical judgement or is it an experienced guess?

I would presume most of the objects in our solar system are the same age or the same age as the creation of the system. Presumably there could be objects that have been "captured" from outer space when they wandered into our sun's gravitational field.

I would welcome some learned comments on this subject. Thank You

[Bad Buoys]

Frank, if you could please delete [up by the edit button while viewing the post to be deleted] your duplicate post of this topic. [done - makc]

Your question about dating planetary items by their craters is answered about a third of the way down the page that Craterchains posted in the February 1, 2005 APOD Iapetus thread

[ruidh]

My question is whether scientists can tell how old an object is from looking at it and inspecting the number of "hits". Is this an emperical judgement or is it an experienced guess?

I think its fairly obvious that if you start with an uncratered surface and objects hit it now and again, the number of visible imact craters increases over time. An uncratered surface has been recently altered and a highly cratered surface has been around for a long time without being altered.

Io has few craters and we have observed the active vulcanism which continuously remakes Io's surface. Its surface is geologically young. The Moon has lots of craters and a few areas which were smoothed over by volcanism in the ancient past. It is still a relatively old surface.

I would presume most of the objects in our solar system are the same age or the same age as the creation of the system. Presumably there could be objects that have been "captured" from outer space when they wandered into our sun's gravitational field.

Something asteroid sized could have been "created" relatively recently from the breakup of a larger body due to tidal forces or a catastrophic impact. It cold have a relatively "young" surface.

We're really talking about the age of the surface. But it follows that if you have a very old surface, you have a very old object.