How big must an asteroid be for it to survive entry into our atmosphere?

Meteor Crater in Arizona was left by an asteroid about 50 yards across, so look at its effects, and then increase them by... about 4 times?

880 megatons, NASA estimated. So massive local damage, and some brief climate chance (nuclear winter without the radiation). Giant tsunamis if it hit in the ocean.

How big an asteroid needs to be to make it probably depends on what it's made of. If Iron, a basketball- sized chunk might survive. Most of the "shooting stars" we see are the size of sand grains or marbles.

100 yards is plenty big to survive and make a very satisfying bang. How much mass is lost depends a lot on what the asteroid is made of, its shape and density, how fast its going and its angle of approach. Very large asteroids, miles in size, would barely have "their paint singed" before they impacted and if they hit an ocean, the ocean would provide no real resistence.

It would depend greatly on the speed of the object and it's trajectory.

Very large objects at a very high speeds may never make it to the earth's surface, either vaporizing or exploding from the tremendous heat before they ever reach the surface.

And object could be very very small (grain of sand)with the right flight path but not be noticed by anyone.

Lets just say an asteroid half the size of the moon and were hooped.

Depending on speed, objects as small as 100 m in diameter are historically extremely destructive.

Compressing air makes it warmth up. that's how a diesel engine works. Air interior the cylinder is compressed adequate so as that as quickly as gasoline is injected it burns without wanting a spark plug. the comparable element happens to spacecraft and meteors, with the air being compressed ahead of them as they commute. there is not any air in area so gadgets can commute very rapid without heating.