Spitzer and Hubble find 'Big Baby' galaxy in the early Universe - Spitzer/IRAC view
This image demonstrates how data from two space observatories, the Spitzer and Hubble Space Telescopes, are used to identify one of the most distant galaxies ever seen. This galaxy is unusually massive for its youthful age of 800 million years. (After the Big Bang, the Milky Way by comparison, is approximately 13 billion years old.)
The Spitzer Infrared Array Camera (IRAC), easily detects the galaxy at longer infrared wavelengths. Spitzer's IRAC is sensitive to the light from older, redder stars, which should make up most of the mass in a galaxy. The brightness of the infrared galaxy suggests that it is quite massive.