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.
it makes an Earthquake
Asteriods are composed of rock that broke off of other planets.
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
it makes an Earthquake
an earthquake
Asteriods are composed of rock that broke off of other planets.
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.
It creates mountians
it makes a mountain
armageddon
mountains are formed
a big explosion occors