Before I go home, let you all see a horse nebula. It's very
nice, too bad no colour, because of the particular technology
used.
Explanation: Why is the Horsehead Nebula surrounded by a bubble?
Although glowing like an emission nebula, the origin of the bubble,
known as Barnard's Loop, is currently unknown. Progenitor
hypotheses include the winds from bright Orion stars and the
supernovas of stars long gone. Barnard's Loop is too faint to be
identified with the unaided eye. The nebula was discovered only in
1895 by E. E. Barnard on long duration film exposures. The above
image was taken in a single specific color emitted by hydrogen to
bring out detail. To the left of the Horsehead Nebula, visible as
the small dark indentation near the image top, is the photogenic
Flame Nebula.
