What degree of damage to the earth by this object?

Question

An object the size of a grain of sand moving as close to the speed of light as possible and hitting the earth. If not the size of a grain of sand then what size? What is the fastest natural moving object in space?

Answer 1

An object with the density of rock would need to be at least 9 centimeters in diameter in order to reach the surface of the Earth without burning up in the atmosphere, even if it were traveling at 99% of the speed of light and hitting the atmosphere head-on. It could be a bit smaller than that if it were more dense, like the density of iron.

High energy cosmic rays are often composed of protons (ionized Hydrogen nuclei) and do travel through space at near-light speeds. These are absorbed by the atmosphere too.

Answer 2

In order for the grain to get enough speed to damage the Earth, it would have to get energy from somewhere. The energy gets converted to speed, then when the grain hits the Earth, the speed is converted back to energy.

I don't know of any method to transfer enough energy into a grain of sand, for it to damage the Earth much. Even at 99.9999999% of the speed of light, the grain has only enough energy to blast a crater about 7 to 15 miles across.

Answer 3

It would burn up in the atmosphere. It would take an object about the size of a car to make it through and even then it would probably only cause a very small crater. In space there are lots of objects that move as close to the speed of light as you can get. Quick examples are cosmic rays and neutrinos.

Answer 4

Who cares? With so many serious problems in this world, you're worrying about a grain of sand.

Answer 5

The earth will vaporize but it will have taken infinite energy to get it going that fast so I'm not too worried about it.