Identifying meteorites

Factual Questions
1

I caught a bit of a TV show last night that was about a guy who drove around the Prairies looking for Meteorites. He hosted “Odd Rock Shows” that were advertised and people would bring in their rocks that they thought were meteors and he would either positively or negatively ID them. After a couple months, he had yet to find a solid “positive” meteorite. However, he did find several he wasn’t sure of. All of them had what appeared to be scorched/melted from re-entry. He kept them and took them back to the U and investigated them a little more closely. All of them came back as negative as meteorites, but most were still “unidentified”. Basically, “We don’t know what these are, but we do know they are not meteorites.”

How can they be so sure? Is there a certain characteristic that all meteorites must have? Is it possible that there are still “unidentified” styles of meteorites? How would scientests know it if they found one of those?

2

http://www.novaspace.com/METEOR/Find.html

http://www.themeteorites.com/TM2/Howtorecog.htm

3

Here’s a decent article on the subject.

4

There was a notable meteorite tonight over the north-midwest (Tennesee-Illinois).

Geologists can look at a chunk of rock and figure out it’s pretty old. Pretty much because any solid thing (like a rock) that has been on earth is easily recognizable.

Throw all rocks at bernse

I’m kidding :b

5

One bizzare thing about medium to large meteorites is that the middle of the rock can remain cold - they are very cold in outer space due to radiative heat loss, and only the outside gets warm on the atmospheric entry.
Apparently what you see in the sky is the shockwave in front of the meteor glowing, and the meteor is not affected by friction so much as by the heat of the shockwave-most of which is dissipated behind the meteor.

6

I’ve heard it said that a meteorite came from Mars. How can this be? What happened on Mars to cause a piece of it to attain escape velocity? And how can you look at a rock and tell it came from Mars?

7

Apparently they tell it is from Mars by analysing the tiny inclusions of Mars’s atmosphere which are locked inside the rock during its long journey…
The martian rocks would have been blasted off Mar’s surface by a meteorite impact, no doubt actually an impact of a small asteroid wandering out of the nearby main asteroid belt.
This also happens with lunar impacts, but I can’t remember hearing of one from Venus…