Sunday, October 16, 2011

Horsehead Nebula

I've always seen pictures of the Horsehead Nebula, but I just realized that I know nothing about it. So I thought this would be a good opportunity to figure that out.

The Horsehead Nebula, also known as Barnard 33, is located on the east side of Orion's Belt, about 1500 light years away from the Earth.  It gets its name because the shape of the dust and gas clouds resembles that of a horse's head when views from the Earth. The Horsehead Nebula is a dark nebula, which means that it is a very dense interstellar cloud. In this case, the Horsehead Nebula obscures the light of the emission nebula IC 434, in which it is located.

The red glow around the nebula comes from hydrogen gas that is ionized by the star system Sigma Orionis. Sigma Orionis is system of five stars in Orion. The main components of the system are two hydrogen-fusing dwarf stars in binary, Sigma Orionis AB. The bright spots just inside the base of the nebula are young stars being born.


  1. Awesome picture!! I always wonder how retouched/enhanced these images are... they MUST be retouched, right???

  2. I remember reading somewhere that people use special filters because it's out of our visible range... I'll look up the details more carefully and try to make that into a post :]

  3. a lot of this stuff actually is in our visible range. when ionized hydrogen recombines, it emits Balmer lines (when an electron transitions from a higher level to n=2, which is often an intermediate step on the way to n=1). these are in the visible spectrum. the blue part of the image is probably a reflection nebula - this occurs because dust scatters blue light (similar to our atmosphere) so dust behind bright stars looks blue because it is reflecting the blue light (also something we can see with our eyes).

    i wonder what this would look like through the eyepiece of a telescope?