APOD 4.4

Peculiar Galaxies of Arp 273 (2011 April 21)

This picture is of the two galaxies of Arp 273. They are over 300 million light-years from the Milky Way Galaxy. There are about 5 bright spiky stars that are in the foreground of this picture. These stars are actually inside of the Milky Way Galaxy. So even with the distance between those stars and Arp 273, you can get a sense of how large these galaxies are. Their distorted appearance is due to gravitational tides as the two galaxies experience close encounters. This isn't strange at all though because interacting galaxies are actually very common. One example is with the Andromeda Galaxy and our own Milky Way. The Andromeda Galaxy is about 2 million light-years away and is getting closer to us. By observing Arp 273, astronomers may get a better sense of what could happen as the Andromeda Galaxy approaches us. In a video sequence from "Infinity Express: A 20-Minute Tour of the Universe," one can actually watch the results of these encounters that scientists have developed thanks to research and computer graphics. This was actually released in the Smithsonian Institution's National Air and Space Museum in Washington, D.C. in 2002 and was shown in the Einstein Planetarium. The result is supposed to be a merger into a single galaxy of stars. To be able to see this in the planetarium must have been amazing.