Astronomy picture of the day - 2015 September 11 - A Giant Squid in the Flying Bat

A Giant Squid in the Flying Bat 
Image Credit & Copyright: Steve Cannistra (StarryWonders)

Explanation: Very faint but also very large on planet Earth's sky, a giant Squid Nebula cataloged as Ou4, and Sh2-129 also known as the Flying Bat Nebula, are both caught in this scene toward the royal constellation Cepheus.Composed with a total of 20 hours of broadband and narrowband data, the telescopic field of view is almost 4 degrees or 8 Full Moons across. Discovered in 2011 by French astro-imager Nicolas Outters, the Squid Nebula's alluringbipolar shape is distinguished here by the telltale blue-green emission from doubly ionized oxygen atoms. Though apparently completely surrounded by the reddish hydrogen emission region Sh2-129, the true distance and nature of the Squid Nebula have been difficult to determine. Still, a recent investigation suggests Ou4 really does lie within Sh2-129 some 2,300 light-years away. Consistent with that scenario, Ou4 would represent a spectacular outflow driven by atriple system of hot, massive stars, cataloged as HR8119, seen near the center of the nebula. If so, the truly giant Squid Nebula would physically be nearly 50 light-years across.