If you think Earth is a mess, consider the turmoil in the constellation Hydra, where astronomers have spotted two monster galactic clusters slamming together in one of the biggest collisions ever recorded.

The cosmic smash-up poses no danger to Earth � it is located about 800 million light-years away and the galaxies involved tend to speed by each other without crashing � but our own Milky Way could be on a similar collision course in a few billion years.