| MadSci Network: Astronomy |
My dad found a rock that looks like a it came from space. It is black and has gas pockets magnets stick to it. Could it be from space?
Rocks from space that survive to the surface of the Earth are called meteorites. Thousands of these fall every year, and it isn't unusual for people to find them. The object you describe could be a meteorite, but it needs to be examined by an expert to know for sure.
Lets consider each of the characteristics you describe. First, you say the stone is black. When rocks in space cross paths with the Earth, they are traveling very fast. As they pass through the atmosphere they compress air in front of them, heating it to thousands of degrees. This makes them burn very brightly (producing what we call a meteor, or shooting star), and the outer surface of the object melts. If it survives to the ground, we often find a rock with a glassy black crust. But many Earth rocks, such as the very common basalts, are also black.
Second, you describe gas pockets. This is something that you do not find on meteorites. They are solid objects that are either smooth, or have shallow indentations on their surface called regmaglypts. True gas pockets would suggest something produced volcanically on Earth.
Finally, you say that magnets stick to it. Most meteorites are stony, but frequently contain high amount of metallic iron. This means that they are commonly attractive to magnets (but not always). But the same is true of many terrestrial stones.
Statistically, what your dad found is much more likely to be terrestrial than a meteorite. It could also be slag, a byproduct of smelting operations that is frequently mistaken for meteorites. If you have a local college with a geology department, you should take your stone there and ask for an opinion. You can also use the Internet to look at pictures of meteorites, and see if any look like what you have. These sites have many good images:
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