M76 is a wonderful nebula to observe visually through the 20in telescope
on a dark night. It displays two distinct features- the bright inner rectangle
and very dim outer loops. Like most nebulae of this type, these loops of
material (the rectangular part is a torus viewed edgewise) are cast off
by the death of star of average mass. Stars more massive would actually
explode. This process is much more non-violent and results in the convoluted
bubbles shown here. The distance to M76 is uncertain; but most sources
place it between 3-5 thousand light years away. This would make the bubble
of gas about a light year across. The full resolution
image (click on left) best shows the very heart of
the nebula where the central star resides. The image shows a double star-
the top of which is distinctly blue. It is this hot star that is responsible for making the Little Dumbell glow!