IC 1396 is an emission nebula, ionized by a blue, type O star, the brightest star at one o'clock to the center of the photo.
Twice as far as the Orion Nebula
The distance to the nebula is less than 3000 light years, about twice as far as the Orion Nebula. IC 1396 is several hundred light-years in diameter, and extends over three degrees on our sky. This is the same angular diameter as six full moons. IC 1396 is so large on the sky that if one could see it with the naked eye (the nebulosity
is extremely faint), one could not entirely cover it with the thumb at arms length.
12000 solar masses
An extensive study published in 1996 in Astronomy and Astrophysics concluded that the entire mass of IC 1396 is around 12,000 solar masses. Approximately 4000 solar masses are cold, molecular gasses, - visible on the photo as dark clumps. The fluorescing areas are ionized gas consisting of about 300 solar masses.
IC 1396. 5 Sept 2016, Loc: Rennesøy, Norway, Telescope: Esprit 120 ED, Camera: Apogee Alta U16M, Mount: ASA DDM160, Exposure: LRGB 6/6/6/6 min, Field: 2,3 x 2,4 degrees.