About Meteorites

Meteorites are pieces of rock that formed in space that have made it all the way through Earth's atmosphere and hit the ground. 

Meteorites record billions of years of history from the formation of the very first solids through to the evolution of planets and, in some cases, the complete destruction of early planetary bodies. Researchers study meteorites to understand what was happening in the early solar system, how we went from small lumpy asteroids to planets, and what made Earth turn out so different to the other planets.

Learn more about meteorite research at UMN

There are lots of words that we use to talk about distinct periods in a meteorite's life. For instance, "asteroid" is the name we give to a body of rock in space. These can vary in size quite dramatically, but very small ones can also be referred to as a "meteoroid". If an asteroid or meteoroid travels into Earth's orbit and gets close enough, it can enter the atmosphere. At this point, it becomes a "meteor".

Meteors fall through the atmosphere at break-neck speeds and the friction of the air against the meteor causes it to heat up, the outer layer to melt and be stripped away, and for the meteor to glow. If it's very bright, we call this a "bolide" or a "fireball". In recent years, scientists have used fireballs to work out where a meteorite might have landed so that they can go and collect it, and to calculate the orbit of meteor.

Finally, if any material survives its journey through the atmosphere and hits the ground, it becomes a "meteorite".

There are over 45 different types of meteorite, but they can be broadly categorized into stony meteorites, iron meteorites, and stony-iron meteorites based on their general composition.

Learn more about the different types of meteorites

Meteorites can come from asteroids (or be asteroids) and from other planets. With few exceptions, each type of meteorite has its own origin or "parent body". The ordinary and enstatite chondrites come from the inner solar system, but the carbonaceous chondrites originate in the outer solar system. Igneous meteorites called achondrites come from various different planetary bodies including the Moon, Mars, and large asteroids like Vesta. Some groups like the iron meteorites don't have an obvious parent body at all because it was completely destroyed in the early solar system!

Researchers study the mineral and isotope compositions of meteorites to look for similarities and differences, helping them to work out where each particular meteorite might have come from and to understand the geology of it's parent body.

Meteorites are named after the location or region where they were found, and numbered sequentially. As an example, the first meteorite approved as part of the UMin repository is NWA 16313. NWA stands for Northwest Africa (it was found in Algeria) and is the 16313th meteorite to be found in this region. 

The Nomenclature Committee of the Meteoritical Society is responsible for giving meteorites official names, and aims to ensure that there is no ambiguity or duplication of names. 

Every square foot of Earth has the same chance to catch a meteorite, but that means only in very rare cases do they land directly outside your house. Instead, people have to go hunting for them. 

The best places to find meteorites are very old, dry landscapes. The older the land, the longer it has had for meteorites to land on it. Drier places also mean that the meteorites weather more slowly and there's less vegetation to cover them up. In an ideal world, we would also like the natural stone and soil to be a completely different color to meteorites so that we can easily spot them. 

Most meteorites being collected today come from countries in northwestern Africa like Morocco and Algeria, from the Australian outback, the Atacama desert, and Antarctica. 

The majority of meteorites are dark colored stones that feel much heavier than you'd expect and often look out of place. Most are magnetic and a freshly fallen meteorite will have a delicate, black glassy layer on the outer surface called a "fusion crust". This can flake off and reveal the inside of the meteorite and you might be able to see meteorite-specific features like chondrules. The longer a meteorite has been on the surface, the more weathered it gets. Old meteorites can be very fragile so scientists, museums, collections, and repositories work hard to keep them safe.

Be careful though! Lots of Earth's rocks look very similar to meteorites, and many weathering processes can mimic the look of a fusion crust. 

"Meteorwrong" is an affectionate term used by meteorite researchers for rocks that look like meteorites, but aren't. The most common meteorwrongs include stones with desert varnish (a coating that forms in hot, arid environments), mining waste, iron ore or iron ore-bearing rocks, terrestrial igneous rocks, and we've also seen some very convincing limestone.

We can often identify a meteorwrong from a photo but sometimes it can be quite difficult. At that point, we have to carry out the same sort of analysis we would do for a meteorite. This is a time consuming process and can be expensive, so we only do this when we think there's enough of a chance that it could be a meteorite. 

Lastly, keep in mind that meteorwrongs are much more common than meteorites! 

If you come across a freshly fallen meteorite (which does happen), here are a few things you should do.

1. Take a photo of the rock where it is, making sure there's plenty of light and the image is in focus.

2. Make note of where you found it. A written address, street name, map screenshot, co-ordinates etc. are all useful. 

3. Put it in a plastic bag and try not to touch it with your hands. Meteorites aren't dangerous to touch, but sweat and cells from your skin can contaminate it and make certain types of analysis much harder. 

4. Get in touch with a planetary scientist, share the photos, and see what they think!

However! The chances of finding a meteorite are very low, especially in places like Minnesota, but please don't be discouraged if your stone isn't from space. 

Test your meteorite identification skills here!