This is a great picture showing a view of Orion you can’t see with the naked eye. The red is glowing gases, heated by the young bright stars of the region. The blue stars of Orion’s belt are just a few million years old and are illuminating the half-circle of Barnard’s loop which is a couple hundred light years in diameter.
To the left (north) is a dimmer globe of red surrounding the head of Orion. This is the Lambda Orionis star forming region, which was the focus of my PhD thesis. The center of this region has stars that are all around 10 million years old (and not younger) whereas the edge of the bubble has a range of ages from 10 Myr down to 1 Myr old. My thesis conjectured that this was because star formation ceased in the middle about 10 Myr ago due to a hot stars or a supernova clearing out the gas, thus starving the star forming process.
It reminds me of an image I looked at a lot during my thesis work:
http://www.astro.wisc.edu/~dolan/thesis/ori_kc.jpg (note: I did not take that picture — it’s from Sven Kohle & Till Credner)
Originally shared by Astronomy Picture of the Day (APoD)
Orion Over and Under Tibet
Image Credit & Copyright: Jeff Dai
This night was so serene you could see Orion rise downwards. The unusual spectacle was captured in this single-exposure image, featuring a deep sky around the famous constellation of Orion that appeared both above — and reflected in — a peaceful lake in the Gyirong Valley of Tibet, China. Taken last year at this time, the three belt stars of Orion can be seen lined up almost vertically above and below the Himalayan Mountains. The complex Orion Nebula can be seen to the belt stars’ right, while the red-glowing circular structure surrounding Orion is Barnard’s Loop. Also, the bright red star Betelgeuse is doubly visible on the image left, while bright blue Rigel appears twice on the image right. Familiar Orion is becoming increasingly visible as Winter (Summer) descends on the Northern (Southern) hemisphere.