This image from the Spitzer Space Telescope reveals a giant “bubble” in space. Almost 100 light-years across and 15,000 light-years away, the expanding blob is triggering bursts of star formation.

At the bubble’s core sits a cluster of several dozen blazing young stars. These stars—each dozens of times more massive than the sun—drive fierce winds that carve out a void in the interstellar gas and dust.

As the growing bubble plows through space, it compresses gas. The compression triggers new waves of star formation. All along the bubble’s edge new stars begin to light up. The stellar infants begin blowing bubbles of their own. The smaller bubbles (circled for clarity) appear strung out along the main bubble’s edge.

Images like this give astronomers a rare glimpse into how stars are born. In this case the birth of one star cluster gives rise to the creation of several others. Astronomers call this phenomenon “triggered star formation.” By measuring how quickly the bubbles are expanding, researchers estimate that the main cluster formed sometime within the last million years. The newer sites on the bubble’s edge are probably only a few hundred thousand years old.

The photo is part of GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire)—a program that uses infrared light to map our galaxy’s disk. The infrared Spitzer telescope can penetrate the thick, dark dust lanes that normally block our view in this part of the galaxy thus allowing astronomers to study distant stellar nurseries in great detail.

Christopher Crockett