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.

2010 October 27
See Explanation.
Moving the cursor over the image will bring up an alternate version.
Clicking on the image will bring up the highest resolution version

Ultraviolet Andromeda
Credit: UV - NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP)
Optical - Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF

Explanation: This stunning vista represents the highest resolution image ever made of the Andromeda Galaxy (aka M31) at ultraviolet wavelengths. Recorded by NASA's Swift satellite, the mosaic is composed of 330 individual images covering a region 200,000 light-years wide. It shows about 20,000 sources, dominated by hot, young stars and dense star clusters that radiate strongly in energetic ultraviolet light. Of course, the Andromeda Galaxy is the closest large spiral galaxy to our own Milky Way, at a distance of some 2.5 million light-years. Just slide your cursor over the image to compare the appearance of this gorgeous island universe in optical light with its ultraviolet portrait.

Tomorrow's picture: spooky season

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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