25
votes
3answers
1k views

Why are there no asteroids or meteoroids with relativistic speeds?

Cosmic rays can have energies going into the $10^{20}$ eV domain. Asteroids and meteoroids originating in the solar system are probably limited in their speed because they all started out from the ...
0
votes
2answers
29 views

Ways to spot a comet or asteroid?

How do we spot a comet or asteroid if it does not emit light or pass infront of an object which emits light? And if such an object would be on a crash course with our planet how early would we be ...