Are the exact measurements known of how big a meteor needs to be to breach the atmosphere and land on Earth versus burn up in it and disappear?
In: Planetary Science
When I was a youngling at the planetarium I recall them* saying it would have to be about the size of a basketball to reach the ground
composition, angle and speed are variables that change the minimum size between burn and ground impact. i’m sure a theoretical scientist has a working model.
*typical masses of recovered meteorites are in the mass range 100 to 10000 grams; typical lengths are about 3 to 30 cm.*
https://meteorites.ucla.edu/faq/
I can’t find the numbers, but things larger than 100 m can usually make it to the ground in one piece. Smaller things, probably down to somewhere around a 20 cm, will tend to break up in the lower atmosphere, and land on the ground as fragments. Anything smaller will burn up entirely.
We can tell when something will absolutely make it through, and when something will absolutely not make it through. We determine it based on what its made of, how fast its going, how dense it is, and what angle it enters the atmosphere.
But as you get closer to the middle of the two things, it becomes less clear. A 5m iron meteor will always make it through the atmosphere. A 3m rocky meteor never will. But what about a 4m meteor made of both iron and rock?
There are still too many variables to determine, for sure, the exact conditions required for it to reach the earth or burn up.
This is the closest we can get: https://www.purdue.edu/impactearth/ which is pretty good, but not exact.
Burning up in the atmosphere or making it to the ground in one piece aren’t the only possible outcomes. Sometimes meteors explode in the atmosphere, [as happened with the Tunguska event in 1908](https://en.m.wikipedia.org/wiki/Tunguska_event). If the meteor makes it to the ground but not in one piece, does that count?
Questions like this are why I love the ELI5 sub. Great question OP. I’ve THOUGHT about looking for an answer but never do. Thanks!
When they say a meteor burns up, what actually happens? Does it fall apart into smaller and smaller rocks while all the ice and gaseous materials boil away? Will tiny, slower meteorites land over an area? If it’s a small iron meteor, certainly the iron doesn’t go away.
There are some that are so big they will always make it through, and some that are so small they will never make it through, but there’s actually a very large middle area where there are too many variables to know. For example, things like the size, shape, composition, structure, speed, and angle of entry into the atmosphere are all factors, so there’s no one single line where you say on this side it will burn up and on the other it will impact.
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