The Philadelphia Jewish Voice rarely covers Astronomy, but we just got big news from NASA. This is really big news. Actually this is news that stretches a 2.6 million light years to our galaxy’s nearest neighbor the Andromeda Galaxy. We have long known that although the universe in general is expanding and most galaxies have a red-shift indicating they are moving away from us, the Andromeda Galaxy is actually blue-shifted indicating that it is approaching us at 190 miles per second.
Until recently Astronomers had no way to measure the Andromeda Galaxy’s transverse (or sideways) motion, so they couldn’t tell if our galaxies were doomed to collide or if they were merely passing in the night. Now, thanks to seven years of painstaking observations by the Hubble Space Telescope, NASA astronomers have been able to determine that the Andromeda Galaxy is aimed straight at us and will collide in four billion years.
The art work on the right shows what this might look like from Earth. The first image shows the current night sky with our Milky Way visible as a milky band in a dark sky and the Andromeda Galaxy is a small smudge. In successive images you can see the Andromeda Galaxy approach, interact with our galaxy, passing through it and then falling back to form a single vast elliptical galaxy after a total of 7 billion years.
NASA’s animation follows the jump.