NGC 2261
Hubble's Variable Nebula
20" F4.5 170X
Hubble's Variable Nebula lies some 2500 LY away in the constellation monoceros.  Edwin Hubble extensively studied its variable nature.  The nebula is a little less than 1 LY across.  It is believed that knots of dark obscuring gas pass in front of the star casting shadows on the reflection nebula.  Changes in brightness and darker areas of the nebula occur over days and weeks.