NASA’s Spitzer Space Telescope captured this image of a glowing emerald nebula, RCW 120. This region of incandescent gas and dust is located in the murky clouds encircled by the tail of the constellation Scorpius. The green ring of dust is radiating in infrared colors that our eyes cannot see but that show up brightly when viewed by Spitzer’s infrared detectors. They have been rendered into false colors for this spectacular view. Astronomers believe rings like this are created by the powerful light of giant O-class stars, the most massive type of star known to exist.
The green ring (our view of a nearly spherical bubble) is where dust is being hit by winds and intense light from the massive stars. The green color represents infrared light coming from tiny dust grains that have been destroyed inside the bubble. The red color inside the ring shows slightly larger, hotter dust grains, heated by the massive stars.
The flat plane of our galaxy is located toward the bottom of the picture, and the ring is slightly above the plane. The green haze seen at the bottom of the image is the diffuse glow of dust from the galactic plane.
Spitzer has found that such bubbles are common around O-type stars throughout our Milky Way galaxy. The small objects at the lower right area of the image may themselves be similar regions seen at much greater distances across the galaxy. Rings like this are so common in Spitzer’s observations that astronomers have enlisted the public to help find and catalog them. Anyone interested in joining the search as a citizen scientist can visit The Milky Way Project, part of the Zooniverse of public astronomy projects.
Bottom line: Spitzer Space Telescope captured the infrared light from a nebula, RCW 120. Massive O-type stars in the center likely created the green bubble that we see as a ring. This type of bubble is found throughout the Milky Way galaxy.