Science: Cosmic Smashup Predicted, But Earth Will Survive


Astronomers in a NASA news conference Thursday said that years of observations from the Hubble Space Telescope provide grisly details of a long-anticipated galactic smashup. Astronomers had seen the Andromeda galaxy coming at us, but thought there was a chance that its sideways motion would make it miss or graze the Milky Way.

Scientists say the sun and Earth are unlikely to be hit by stars or planets from Andromeda because of the vast emptiness of the two galaxies. So Earth should easily survive what will be a 1.2 million mile per hour galactic merger. Even at that speed, the event would take about 2 billion years.

The only way Andromeda could miss colliding with the Milky Way is if it were moving sideways about six times faster than Hubble indicates it is, said van der Marel, who is publishing the latest findings in an upcoming issue of Astrophysical Journal. Five years ago, Avi Loeb, head of Harvard University's astronomy department, simulated this crash and pronounced a miss unlikely.

Both the Milky Way and Andromeda are about the same size and same age. At times they've been considered virtual twins so it's hard to tell which of the galaxies will get the worst of the collision, van der Marel said.

When the collision is in full swing in 4 billion years, he said the sun will still have another 2 billion years before its expected death. However, by that time it will have grown so large and so hot that Earth might no longer be habitable without super-engineering techniques, he said.




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