ESA Planck Observatory

Launched along with the Herschel Space Observatory in May, the European Space Agency’s Planck Observatory will study the radiation left over from the first 370,000 years after the big bang—known as the cosmic microwave background, or CMB—with three times the sharpness of previous satellites. To detect temperature differences in the CMB as small as millionths of a degree (the equivalent of detecting the body heat of a rabbit on the moon, from Earth), Planck uses two devices, one for high frequencies and one for low. To keep the satellite’s own heat from skewing its observations, Planck’s instruments were cooled in several stages after reaching orbit; now, at­ –459.49ºF, Planck’s High Frequency Instrument is the coldest known object in space. By reading the CMB more accurately than ever before, scientists hope to answer thorny cosmic questions, such as how much of the universe is made of dark matter.
esa.int/planck