Science Daily: "On July 2 the detectors of Planck's High Frequency Instrument reached their amazingly low operational temperature of -273°C, making them the coldest known objects in space. The spacecraft has also just entered its final orbit around the second Lagrange point of the Sun-Earth system, L2. Planck is equipped with a passive cooling system that brings its temperature down to about -230°C by radiating heat into space. Three active coolers take over from there, and bring the temperature down further to an amazing low of -273.05°C, only 0.1°C above absolute zero - the coldest temperature theoretically possible in our Universe."