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.
Collinder 399: The Coat Hanger
Explanation: Is this coat hanger a star cluster or an asterism? This cosmic hang-up has been debated over much of last century, as astronomers wondered whether this binocular-visible object is really a physically associated open cluster or a chance projection . Chance star projections are known as asterisms , an example of which is the popular Big Dipper . Recent precise measurements from different vantage points in the Earth's orbit around the Sun have uncovered discrepant angular shifts indicating that the Coat Hanger is better described as an asterism . Known more formally as Collinder 399 , this bright stellar grouping is wider than the full moon and lies in the constellation of the Fox (Vulpecula).
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| Date | August 26, 2015 |
|---|---|
| Credit | Image Credit & Copyright: John Chumack |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |