ESA Galaxy Clusters.jpg
(545 GHz) The Planck all-sky map at submillimeter wavelengths . The band running through the middle corresponds to dust in our Milky Way galaxy. The black dots indicate the location of the proto-cluster candidates identified by Planck and subsequently observed by Herschel. The inset images showcase some of the observations made by Herschel's SPIRE instrument; the contours represent the density of galaxies.