This glowing green nebula gets its ring-like shape from the powerful light of the most massive stars known to exist.
The ten light-year-wide nebula, named RCW 120 and imaged by NASA's Spitzer Space Telescope, is found in clouds of dust and gas near the tail of the constellation Scorpius. It lies slightly above the flat plane of our galaxy, the hazy glow of which can been seen towards the picture's bottom.
To human eyes the ring of glowing dust is invisible, but it shines in the infrared wavelengths Spitzer sees. Blue represents 3.6-micrometer light, green is 8 micrometers, and red is 24-micrometer light.
The ring is sculpted by a pair of giant "O-type" stars that lie at the ring's center, blowing bubbles with the pressure of intense ultraviolet light. Spitzer observations have found that many of the Milky Way's O-type stars blow similar bubbles of glowing gas. The small objects at this image's right may be similar rings seen at much greater distances across the galaxy.
Citizen scientists can help find more of these rings in Spitzer data with the Milky Way Project, part of the "Zooniverse" constellation of public astronomy projects.
Image: NASA/JPL-Caltech
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