Figure: Milky Way's heavenly twin?: NGC-1232. This beautiful spiral galaxy in the constellation Eridanus is located 100 million light years away, and many astronomers use it as an example of what our Milky Way might look like from outside. Our sun would be located about 2/3 of the way from the core region, in a spot perhaps not unlike what you would find in this image at about the 8 o'clock position. (Credit: European Southern Observatory )
Because light takes time to get from place to place in the universe, from far away, you would see what the Milky Way looked like long ago. The image would show a galaxy younger than ours today. Also, because of the cosmological redshift, the Milky Way would appear to be receding from us at a speed determined by the Hubble Law. At a distance of 300 million light years, the Milky Way would have a recession speed of 5,000 miles/sec. At three billion light years, it would have a recession speed of 50,000 miles/sec. Its image would be that of a galaxy three billion years younger than our Milky Way's current age. Not much will have changed, but at in-between distances perhaps the core of our galaxy would have temporarily flared-up as a Seyfert 'active galaxy'.
Latest studies in 2005-2010 now show that the Milky Way is a barred spiral galaxy similar to the artist rendering shown above. In 2008, it was announced that infrared images from NASA's Spitzer Space Telescope have shown that the Milky Way's elegant spiral structure is dominated by just two arms wrapping off the ends of a central bar of stars. Previously, our galaxy was thought to have four major arms. Image credit: NASA/JPL-Caltech
This answer was updated in 2011.
See my books:
The Astronomy Cafe (1998) and
Back to the Astronomy Cafe (2003) for more FAQs in printed form. Author: Dr. Sten Odenwald, Copyright 2011
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