Collinder 399: The Coat Hanger

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). APOD is also available in: Arabic , Bahasa Indonesian , Catalan , Chinese , Chinese , Czech , Dutch , Farsi , Farsi , Galego , German , French , Hebrew , Japanese , Korean , Montenegrin , Polish , Russian , Serbian , Slovenian , Spanish , Thai , or Turkish