This is picture of a "thin section" of a meteorite. While most meteorites look just like normal rocks to the naked eye, we can cut a very thin slice from one and look at it under normal or polarized light, making pictures like the one above.
Meteorites are rocks that fall to the Earth from space. Some are from the moon, and some are from Mars, but most appear to be from an area known as the asteroid belt, which lies between the orbits of Mars and Jupiter. Meteorites give us a lot of information about the places they're from; in 1996 one meteorite from Mars was reported to show the possible existence of life there once (the final judgement on that hasn't been decided yet).
Most meteorites are found in Antarctica. That's not because that's where most of them land, it's because they're a lot easier to see against the white snow.
PtyS 109 is the PtyS course with the most to say about meteorites.
PtyS 403, PtyS 407, and PtyS 411 all have something to say about meteorites as well.
Some other places you can find information on meteorites include: