May 3, 2011


Today’s Cool Photo of the Week, taken by the Hubble Space Telescope, is of two spiral galaxies bumping up against each other. The bigger galaxy (NGC 2207, on the left) has such a strong gravitational pull that it is pulling the smaller galaxy (IC 2163, on the right) in toward it.  Look at the long, white streak that looks like streamers, or a tail, on the right-hand side of the photograph. These are stars and gases, being pulled so strongly that they seem to stretch out across the light years.

NASA astronomers have calculated that the last time the two galaxies came this close was about 40 million years ago. However, IC 2163 does not have enough energy to escape the bigger galaxy’s gravitational pull, so they will continue to elbow each other as they travel through space, and billions of years from now they will probably merge into one big galaxy. It is believed that our own Milky Way galaxy was formed in just this way.

Don’t you love these Hubble photographs? The opportunity to see not only out into the universe but also back in time is still amazing to me. I never tire of looking at these magnificent images.


Photo: NASA/ESA and The Hubble Heritage Team (STScI)

Posted by: Seymour Simon

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