June 22, 2009
A nebula is a vast cloud of gas and dust. The physical processes that shape its appearance differ depending on whether it is an emission nebula or a planetary nebula.
In the Trifid Nebula (M20), three dense dust lanes cut across glowing gas clouds. The combination creates the object’s distinctive appearance.
Photo by Jim and Janet Castano/Adam Block/NOAO/AURA/NSF
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