End of the galaxy (but don't hold your breath)
BY MICHAEL HANLON
STOP worrying about the end of the world - the end of the whole galaxy is the real problem. Astronomers have calculated that the Milky Way will be destroyed in a headlong, 300,000mph collision with the giant Andromeda galaxy.
Stargazers have spotted several galactic collisions through telescopes and the Hubble observatory. But all these cosmic pile-ups have happened millions or billions of light years away. Now calculations have revealed that our own galaxy, which is shaped like a spiral and contains 100 billion suns, is heading straight for the much larger Andromeda galaxy, two million light years away.
The results will be catastrophic for our galaxy and could spell the end of our planet. "It will be a major car wreck, and we're the Yugo in this one," said Ohio astrophysicist Chris Mihos. As a result of the collision the solar system, at present safely located out on a quiet galactic arm, could end up at the hotbed centre of the new coagulated galaxy.
Galactic centres are not good places to be. "Massive young stars exploding as supernovae and bombardment by comets might make it too harsh for life," said a report in Science magazine.
Lurking at the centres of both galaxies are two giant black holes. After the merger these holes will coagulate like two blobs of mercury to make a colossal star-eater. Still, at least it would be spectacular. Francois Schweizer, a California astronomer, said: "You would be able to read the newspaper at night by the light of the starbursts."
Alternatively, the collision could result in our sun and its planets being flung out of the galaxy altogether. In which case, we are safe, but the night sky will be a dull affair, lit up only by the moon and the six visible planets with not a star in sight. But the end is certainly not nigh. Even at a closing speed of 300,000mph, the two galaxies will only start to distort each other in a billion and a half years and smash together in three billion.
Life on Earth, if it still exists, will be unrecognisable. Indeed, doom may have struck earlier as our sun expands and triggers global warming. If our descendants do survive, perhaps on the cooler outer planets, they are likely to be as different to us as we are to the bacteria billions of years ago.The universe is expanding, which means that, generally, the galaxies are flying apart. But in local "clusters" of galaxies, collisions, though rare, do happen. The stars themselves rarely collide as the two galaxies merge. There is so much empty space between them that even a full, head-on crash usually sees the stars just whizzing by. But out of the cosmic catastrophe life will be born. The Milky Way and Andromeda will coalesce into an ugly blob of stars. Gas and dust clouds will merge and spark the formation of millions of new stars and planets. When the collision is over, a vast number of sunlike stars and planets will age in unison for billions of years.