Except for the plane of our own Galaxy, the brightest far-infrared object in the sky is central region of a galaxy called M82. The nucleus of M82 radiates as much energy in the far-infrared as all of the stars in our Galaxy combined. This far-infrared energy comes from dust heated by a source that is hidden from view. The central regions of most galaxies shine very brightly in the far-infrared. IRAS infrared view of the Andromeda Galaxy - notice the bright central region.
Several galaxies have active nuclei hidden in dense regions of dust.
Others, called starburst galaxies, have an extremely high number of newly forming stars heating interstellar dust clouds. These galaxies, far outshine all others galaxies in the far-infrared.