Post by glactus on Dec 16, 2008 8:53:06 GMT
The Reflection nebula
NGC 1999 is a dust filled reflection nebula located 1,500 light-years from Earth in the constellation of Orion. Magnitude is variable.
Unlike emission nebulae, whose reddish glow comes from excited atoms of gas, reflection nebulae have a bluish cast as their interstellar dust grains preferentially reflect blue starlight.
While perhaps the most famous reflection nebulae surround the bright young stars of the Pleiades star cluster, NGC 1999's stellar illumination is provided by the embedded variable star V380 Orionis.
Extending right of center, the ominous dark nebula is actually a condensation of cold molecular gas and dust so thick and dense that it blocks light. From our perspective it lies in front of the bright nebula, and silhouetted against the ghostly glow.
New stars will likely form within the dark cloud, called a Bok globule, as self-gravity continues to compress its dense gas and dust.
Credits: This is a NASA/Hubble image