It would be a spectacular sight, but no one has ever observed it happening. I think if you apply the current definition of planet to the bodies involved, you could demonstrate that if two 'planets' collide then at least one of them is not a planet.
Asteriods are composed of rock that broke off of other planets.
it makes an Earthquake
they hug each other
asteriods and comets are different because when asteriods hit earth we are going to to have destroyed buildings and places on eath and comets are like particles in the galaxy and its when they destroy planets and make them into a different shape or sized in the galaxy.
Stars or asteriods
Asteriods are composed of rock that broke off of other planets.
it makes an Earthquake
an earthquake
when continents collide you bum your pet hamster
A collision.
Asteriods are made up of rocks, dust,and minerals that float in spaces atmosphere.
Earthquakes and mountain building.
armageddon
it makes a mountain
It creates mountians
a big explosion occors
mountains are formed