Sharpless 27 (Sh2-27) is an extremely large area of faint red emission nebulosity surrounding the star Zeta Ophiuchi in the constellation of Ophiuchus.

Spanning 10 x 15 degrees of sky, Sh2-27 is one of the largest emission nebulae in the sky. At an estimated distance of 550 light-years, this would correspond to a true size of 96 x 144 light-years in space.

Dark nebulae on the lower left side of the nebula have Lynds Dark Nebula catalog designations which include LDN 260, LDN 255, LDN 234, LDN 204.

Sh2-27 was cataloged by Stewart Sharpless in 1959.

Zeta Ophiuchi, at the center of the nebula, is a massive blue-white O-type star with a visual magnitude of 2.54. It is the third brightest star in the constellation of Ophiuchus, but it is greatly dimmed by large concentrations of gas and dust. Were it not so dimmed, it would be one of the brightest stars in the night sky as seen from Earth.

Zeta Ophiuchi does not have a common name. It is located 370 light-years away.

Zeta is a "runaway" star. It is hurtling through space at 86,000 kilometers per hour. It is thought that Zeta was expelled from a binary star system in the Scorpius-Centaurus Stellar Association when its companion star exploded in a supernova.

Zeta has 20 times the mass of the Sun and is believed to be only 3 million years old. With this amount of mass, Zeta will also end its life in a supernova explosion in another 5 million years.

North is to the top in the above image.

Sharpless 27 Catalogs: Sh2-27, Gum 73 Common Name: Zeta Ophiuchi Nebula Object Type: Emission Nebula Size: 12° x 9° Constellation: Ophiuchus Image Field Centered At: RA: 16h 38m 27s Dec: -11° 00' 03"