nematode

Wouldn't that heat up the atmosphere more/faster than a big rock landing in, say, the ocean? I would think the energy to heat water to boiling would be much greater because of the energy density of water compared to air. If all the energy was dissipated in the air, I would expect more total heating of the air than if the rock landed in the water and converted a lot of it to steam/converted underlying rock to magma.

That's very interesting, I did not know that.

That's very interesting, I did not know that.

What made me think of it was an article I read awhile ago that stated the dinosaur asteroid heated the entire atmosphere to over 400 degrees F, basically killing everything instantly that was not underground/in the mud or under water at the time. It is of course quite possible that article was wrong. I think it was trying to explain why large but submerged predators like crocodilians would survive such an event. Another aspect was their cold blooded metabolism, which allowed them to survive a long period of following global cooling due to ash in the air, and lack of food, despite being large predators. Their metabolism could practically stop, like frogs hibernating in winter, and they would be none the worse for wear. (What they ate when they woke up, I have no idea.) I agree local impact would be worse for a large body, I am thinking more of overall planetary impact of an extinction level event. Could it be avoided by breaking up the asteroid before it hit? I am puzzled as to why dispersing it would reduce the overall damage.

I have found there is a common assumption that a big asteroid hitting would be worse (like the dinosaur one) than the same mass and speed of much smaller ones hitting and mostly burning up/exploding in the atmosphere before reaching the ground. In terms of heating up the atmosphere to an unlivable temperature, are they any different? I would think a given mass moving at a given speed would impart the same kinetic energy to Earth and its atmosphere regardless of whether it was a big one or an equivalent mass of small ones hitting at once. If the small ones would do less damage I am curious why, since the total kinetic energy should be the same. In other words would there be any advantage of a meteor defense system if it broke up a large asteroid but all of the pieces would still hit Earth at the same speed as the initial asteroid? I realize if you broke it up further out some of the pieces would miss Earth and that would be a benefit, but that is not my scenario. Thanks.