NGC 2261 is an odd nebula named for Edwin Hubble, who studied it early last century. It’s appearance can change over short periods of time. Hubble’s Variable Nebula is a reflection nebula made of gas and fine dust moving out from the star R Monocerotis. The faint nebula is about one light-year across and lies about 2500 light-years away in the constellation of Monocerotis (the Unicorn). The leading explanation for the nebula’s rapid changes suggests that dense knots of opaque dust is passing close to R Mon and cast moving shadows onto the reflecting dust seen in the rest of the nebula.
Image Credit: NASA / ESA
Data: Mark Clampin (GSFC)
Processing & License: Judy Schmidt, CC BY 2.0