How many meteorites hit Earth each year?
How many meteorites hit the earth each year, and how do they determine that?
It's a bit hard to tell exactly how many meteorites hit Earth each year. Most meteors that you see in the sky are caused by pea-sized pieces of rock and there's a lot of stuff this size in the solar system that Earth can run into! We can estimate the number of meteorites per year by carefully monitering the meteorites per day in one area, for example by using an all-sky camera to image the meteors visible in a given location, and then assume that all areas get roughly the same number of meteorites and add up the total.
Another way to tell how many meteorites hit Earth each year is to look at the number of meteorites found in dry regions where there isn't much vegtation or erosion (like deserts), where you expect to be able to find most of the meteorites that fell. We can get an estimate of how long ago the meteorite fell to Earth by looking at how it's been weathered, or altered by Earth's atmosphere and the local climate. Then we can plot how many meteorites fell at that region per year.
However, I can still find a lot of different estimates for how much stuff hits Earth each year, partly because different studies look at different size ranges, and all the procedures have errors. Estimates for the mass of material that falls on Earth each year range from 37,000-78,000 tons. Most of this mass would come from dust-sized particles.
A study done in 1996 (looking at the number of meteorites found in deserts over time) calculated that for objects in the 10 gram to 1 kilogram size range, 2900-7300 kilograms per year hit Earth. However, unlike the number above this does not include the small dust particles. They also estimate between 36 and 166 meteorites larger than 10 grams fall to Earth per million square kilometers per year. Over the whole surface area of Earth, that translates to 18,000 to 84,000 meteorites bigger than 10 grams per year. But most meteorites are too small to actually fall all the way to the surface. (This study was led by P. A. Bland and was published in Monthly Notices of the Royal Astronomical Society.)
Get More 'Curious?' with Our New PODCAST:
- Podcast? Subscribe? Tell me about the Ask an Astronomer Podcast
- Subscribe to our Podcast | Listen to our current Episode
- Cool! But I can't now. Send me a quick reminder now for later.
How to ask a question:
If you have a follow-up question concerning the above subject, submit it here. If you have a question about another area of astronomy, find the topic you're interested in from the archive on our site menu, or go here for help.Table 'curious.Referrers' doesn't existTable 'curious.Referrers' doesn't exist
This page has been accessed 97351 times since February 18, 2003.
Last modified: June 4, 2003 9:47:16 PM
Ask an Astronomer is hosted by the Astronomy Department at Cornell University and is produced with PHP and MySQL.
Warning: Your browser is misbehaving! This page might look ugly. (Details)