This artist's animation demonstrates that an invisible galaxy shrouded in
dust can become glaringly bright when viewed in infrared light. The movie
begins with a visible-light view, showing a dark blob of a galaxy that is
so shrouded in dust it appears invisible. The picture then transitions to
what the same region of space might look like in infrared light. A galaxy
appears out of the darkness, because its heated dust glows at infrared
wavelengths.
NASA's Spitzer Space Telescope uncovered a hidden population of invisible
galaxies like these using its highly sensitive infrared eyes. The dusty
galaxies are among the brightest in the universe and are located 11
billion light-years away, back to a time when the universe was 3 billion
years old. The universe is currently believed to be 13.5 billion years
old.
Astronomers are not sure what is lighting up these cosmic behemoths, but
they speculate that quasars--the most luminous objects in the
universe--may be lurking inside.
