Emission nebula IC 1396. Optical image of the glowing cosmic gas and dark dust clouds of the emission nebula IC 1396, which lies nearly 3,000 light years from Earth in the constellation Cepheus. This star-forming region spans hundreds of light years and is energised by the bright blue star HD 206267 (centre). The prominent star at top left is Mu Cephei, which was named the Garnet Star by William Herschel. It is an M2 bright supergiant with a diameter larger than that of Jupiter's orbit. Mu is one of the most luminous stars in the Galaxy, emitting 350,000 times the power of our Sun. The Elephant's Trunk nebula can also be seen just below centre. Imaged by NASA's Chandra X-ray Observatory.