collision

Via NASA:

These two mighty galaxies are pulling each other apart. Known as the "Mice" because they have such long tails, each spiral galaxy has likely already passed through the other. The long tails are created by the relative difference between gravitational pulls on the near and far parts of each galaxy. Because the distances are so large, the cosmic interaction takes place in slow motion -- over hundreds of millions of years. NGC 4676 lies about 300 million light-years away toward the constellation of Bernice's Hair (Coma Berenices) and are likely members of the Coma Cluster of Galaxies. The above picture was taken with the Hubble Space Telescope's Advanced Camera for Surveys in 2002. These galactic mice will probably collide again and again over the next billion years until they coalesce to form a single galaxy.

This happened at a busy intersection in the heart of Warsaw. There was a miscommunication by train operators resulting in pretty much the least exciting collision possible.

...pole.

Researchers have found evidence of the world that crashed into the Earth billions of years ago to form the Moon.

Analysis of lunar rock brought back by Apollo astronauts shows traces of the "planet" called Theia.

The researchers claim that their discovery confirms the theory that the Moon was created by just such a cataclysmic collision.

The study has been published in the journal Science.

This beautiful and eerie photograph is evidence of what astronomers believe could be remnants of a head-on collision of 2 asteroids, resulting in an X-shaped debris pattern ahead of a long stream of dust that's usually indicative of a comet.