M 43 is the round nebula crossed by a dark lane of gas and dust near the
bottom center of this image. The star in the middle of this glowing
circle is the source of its energy. In this image, it is obvious that
M 43 is actually part of the huge nebula region which includes M 42,
The Great Orion Nebula. Just a portion of the Orion Nebula is visible in
the top half this image, but there (if you look at the "original" size
view) you can clearly see the 4 stars of the "Trapezium", which provide
the energy to light up the Orion Nebula.

Image data:
Camera: Canon 350 XT (modified)
Exposure: Color = 30 seconds x 20, 5 minutes x 13 (from January 20, 2007 image of M 42)
Hydrogen-alpha (7 nm) filtered, used as luminance layer: 30 sec x 58, 5 min x 28
Telescope: 10" Schmidt-Newtonian, Baader MPCC