NGC 188

File:Open cluster HR diagram ages.PNG

HR diagram showing the main sequence turnoff of NGC 188 and M 67, indicating their relatively high ages

NGC 188 (also known as Caldwell 1 or the Polarissima Cluster<ref name="interstellarum">Template:Cite book</ref>) is an open cluster in the constellation Cepheus. It was discovered by John Herschel in 1825. Unlike most open clusters that drift apart after a few million years because of the gravitational interaction of our Milky Way galaxy, NGC 188 lies far above the plane of the galaxy and is one of the most ancient of open clusters known, at approximately 6.8 billion years old.<ref name="VandenBerg"> Template:Cite journal</ref>

NGC 188 is very close to the North Celestial Pole, under five degrees away, and in the constellation of Cepheus at an estimated 5,000 light-years' distance, this puts it slightly above the Milky Way's disc and further from the center of the galaxy than the Sun. Template:Clear left

External links

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• NGC 188 at SEDS NGC objects pages
• NGC 188 at NightSkyInfo.com
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• Template:CelestialRefEx

Template:Sky Template:Catalogs Template:Caldwell catalogue Template:Ngc5 Template:Cepheus (constellation)