Astronomy Picture of the Day

Explanation: What causes Hubble's Variable Nebula to vary? The unusual nebula pictured above changes its appearance noticeably in just a few weeks. Discovered over 200 years ago and subsequently cataloged as NGC 2661, the remarkable nebula is named for Edwin Hubble, who studied it earlier this century. Hubble's Variable Nebula is a reflection nebula made of gas and fine dust fanning out from the star R Monocerotis. The faint nebula is about one light-year across and lies about 2500 light-years away towards the constellation of Monocerotis. A leading variability explanation for Hubble's Variable Nebula holds 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.

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Publications with keywords: Hubble space telescope - variable - reflection nebula
Publications with words: Hubble space telescope - variable - reflection nebula
See also:

• Reflections on the 1970s
• Stardust in Perseus
• Pleiades and Stardust
• NGC 7129 and NGC 7142
• Wisps of the Iris Nebula
• vdB 152: Reflection Nebula in Cepheus
• The Merope Reflection Nebula

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