if an asteroid were to hit earth, how big would it have to be to make a crater and not just vaporise in the atmosphere?
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1 Answer
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Roughly 25 Meters
I don't know what you would consider a 'crater', because a pebble landing in mud will create a 'crater'. And very small particles can rain down as dust and make it all the way to the surface because they decelerate very quickly in the upper atmosphere. So in that sense, there is no limit to how small a meteor can be and make it to the ground.
If we assume a large enough meteor to stay mostly in one piece and make a crater big enough to do some kind of damage, that number is on the order of 25 meters.
From NASA:
https://www.nasa.gov/mission_pages/asteroids/overview/fastfacts.html
Space rocks smaller than about 25 meters (about 82 feet) will most likely burn up as they enter the Earth's atmosphere and cause little or no damage.
If a rocky meteoroid larger than 25 meters but smaller than one kilometer ( a little more than 1/2 mile) were to hit Earth, it would likely cause local damage to the impact area.
We believe anything larger than one to two kilometers (one kilometer is a little more than one-half mile) could have worldwide effects. At 5.4 kilometers in diameter, the largest known potentially hazardous asteroid is Toutatis.
