NGC 2261, also known as Hubble's Variable Nebula, is a reflection nebula located in the constellation Monoceros. It is about 2,500 light-years away from Earth and is associated with the young star R Monocerotis, which is responsible for illuminating the surrounding gas and dust. The nebula is notable for its changing appearance, which is caused by the varying brightness of R Monocerotis. Observations have shown that the nebula's shape and brightness can change over time, making it a fascinating subject for astronomers studying stellar formation and the dynamics of interstellar matter.