NGC 6888, also known as the Crescent nebula, is an emission nebula in the constellation Cygnus, about 5000 light-years from Earth.
It is formed by the stellar wind from the Wolf-Rayet star WR 136 (HD 192163), the brightest star at its center, colliding with the slower wind expelled by the star when it became a red giant about 250,000–400,000 years ago.
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