If you are hunting for a meteorite like the one thought to have fallen near St. Thomas, Ont., this week, how do you know if you've found one? And if you have, what should you do with it?
Here are some tips from scientists at Western University's meteor physics group.
What do meteorites look like?
Meteorites look like rocks, but they tend to stand out from other rocks. For one thing, if they have landed recently, they aren't partly embedded in the soil like other rocks.
"They really sit on the surface and they look weird," says Phil McCausland, assistant professor and meteorite curator at Western University. "They kind of attract your attention."
A freshly fallen meteorite is black and its surface isn't shiny – it has more of a matte finish.
"It almost looks like it's painted black," McCausland says.
The millimetre-thick black crust on the outside of a meteorite is caused by the melting of the outer surface as it falls through the atmosphere and heats up from the friction.
The surface of the meteorite tends to be smooth with dimples.
Some, but not all meteorites are attracted to a fridge magnet.
What's the best way to look for a meteorite?
Meteorite researchers say the best way to scan for rocks from space that have landed on Earth is with your eyes. Meteorite researchers who have a good idea where a meteorite has fallen sometimes do line searches where they sweep back and forth in straight, parallel lines across a field.
If you are looking for a meteorite outside your own property, researchers suggest that you get permission from the property owner first.
Can meteorites be dangerous?
As they're falling, they're as dangerous as any other falling rock. And once they've landed, they're no more hazardous than any other rock.
What should I do if I find one?
To avoid contaminating the rock, McCausland recommends that you pick it up with a plastic bag turned inside out, either one from the grocery store or a Ziploc bag. Then turn it right-side-in and seal it.
Western's meteor physics group suggests that you contact them so they can "type" it – that is, run the necessary lab tests to certify it as a bona fide meteorite, as well as collect scientific data on the meteorite.
Who owns the meteorite?
In Canada, meteorites are owned by the owner of the property where they were found.
Can I sell the meteorite for a lot of money?
In order to sell a meteorite, it needs to be first "typed" and certified as a real meteorite, says Peter Brown, director of Western's Centre for Planetary Science and Exploration.
Prices vary from about five cents per gram up to $1,000 a gram, depending on the composition of the meteorite. The rarer the composition, the more it's worth.
Brown added that while some meteorites can sell for a lot of money, most meteorite hunters spend more money getting to the site where they might find a meteorite and searching for it than they will get from selling it.
He believes the scientific value of meteorites is far greater than their monetary value.