C46 (NGC 2261)
This fan-shaped cloud of gas and dust shines by the light of a bright star at the bottom end of the nebula. The nebula is lit up by the massive, young star dubbed R Monocerotis (R Mon for short). Astronomers believe that dense knots of opaque dust pass close to R Mon and cast moving shadows onto the reflecting dust seen in the rest of the nebula.
Credits: NASA/ESA and the Hubble Heritage Team (AURA/STScI)