Crescent-shaped planetary nebula SH2-188 glows in wisps of green in this skywatching image.
Astrophotographer Bill Snyder captured this stunning deep-space image Feb. 22, 2012 at his Home Observatory in Connellsville Pa.
Sh2-188, also referred to as the Dolphin nebula, is approximately 850 light years from Earth in the constellation Cassiopeia. A light-year is the distance light travels in one year, or about 6 trillion miles (10 trillion kilometers).
The unique, crescent shape of the nebula led astronomers to initially believe SH2-188 was the remnant of a supernova. However, SH2-188 was confirmed to be an asymmetrical planetary nebula.
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Nina Sen is a freelance writer and producer who covered night sky photography and astronomy for Space.com. She began writing and producing content for Space.com in 2011 with a focus on story and image production, as well as amazing space photos captured by NASA telescopes and other missions. Her work also includes coverage of amazing images by astrophotographers that showcase the night sky's beauty.