Volunteers using the web-based Milky Way Project brought star-forming features nicknamed "yellowballs" to the attention of researchers, who later showed that they are a phase of massive star formation. The yellow balls -- which are several hundred to thousands times the size of our solar system -- are pictured here in the center of this image taken by NASA's Spitzer Space Telescope. Infrared light has been assigned different colors; yellow occurs where green and red overlap. The yellow balls represent an intermediary stage of massive star formation that takes place before massive stars carve out cavities in the surrounding gas and dust (seen as green-rimmed bubbles with red interiors in this image).

Infrared light of 3.6 microns is blue; 8-micron light is green; and 24-micron light is red.

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

For more information about Spitzer, visit http://spitzer.caltech.edu and http://www.nasa.gov/spitzer.