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APOD

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

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Arp 273

Explanation: The two prominent stars in the foreground of this colorful skyscape are well within our own Milky Way Galaxy . Their spiky appearance is due to diffraction in the astronomer's telescope. But the two eye-catching galaxies in view lie far beyond the Milky Way , at a distance of about 200 million light-years. Their distorted appearance is due to gravitational tides as the pair engage in close encounters . From our perspective, the bright cores of the galaxies are separated by about 80,000 light-years. Cataloged as Arp 273 (also as UGC 1810), the galaxies do look peculiar , but interacting galaxies are now understood to be common in the universe. In fact, the nearby large spiral Andromeda Galaxy is known to be some 2 million light-years away and approaching the Milky Way. Arp 273 may offer an analog of their far future encounter . Repeated galaxy encounters on a cosmic timescale can ultimately result in a merger into a single galaxy of stars.

Date November 15, 2008
Credit Credit & Copyright: Adam Block , Mount Lemmon SkyCenter , University of Arizona
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
A service of: ASD at NASA / GSFC,
NASA Science Activation & Michigan Tech. U.