It is comforting to think - in a groovy, Age of Aquarius kind of way - that the ultimate destruction of our universe will be precipitated by an enormous galactic lovefest. This crackerjack computer model, created by astronomer Arman Khalatyan at Germany's Astrophysikalisches Institut Potsdam, shows how the calamitous coupling will likely go down starting now until 10 gigayears (10 billion years) in the future.
Most galaxies are running away from the Milky Way at a tremendous speed due to the initial force of the Big Bang, an effect known as the Hubble expansion. But one spiral-shaped suitor, Andromeda, inches closer day by day. The galaxy has been caught in the snare of our gravitational field and, as the two celestial bodies sidle up to each other at 310,000 m.p.h., a collision is expected to occur in about 2.3 billion years. (Using binoculars in a dark location, you can see a similar ongoing encounter between the gorgeous Whirlpool Galaxy and homely dwarf galaxy NGC 5195.)
The first encounter will probably just be an awkward peck on the cheek as Andromeda touches the Milky Way and races away to grab another drink.
But it will swing back with more confidence about 3 billion years later, and this time will score. Some studies predict that the sun will have boiled away the earth's oceans at this point. But if mankind is still hanging around, the night skies will be crazy as the two star systems begin to entwine. The massive black holes at the center of each galaxy will merge, causing a chaotic swarm of stars to conform into a football structure. Astronomers call this new entity Milkomeda.
As gigayears pass, Milkomeda's fuel reserves will tire out and its stars will begin to fade. Our sun might expand into a red giant that swallows the remnants of earth, then shrink down to a dark planet-sized cinder. So if you are the pessimistic type who believes that relationships don't matter in the grand scheme of things - well, you're right and you're wrong. (Kudos to New Scientist for finding the animation.)