This
nebula is a
cloud of dust that is reflecting the light from a
nearby star. Light with shorter
wavelengths is better bounced by the particles, so they usually appear to be
bluish-purple in colour.
These nebulae tend to be smaller as dust lanes are usually smaller than the vast rifts of gas found in Emission Nebulae.
For more of this kind of amusement, scope the Astronomy Picture Of the Day.