Satellite hints at slower expansion rate for universe
ESA and the Planck Collaboration
In October, astronomers said good-bye to the European Space Agency’s Planck satellite, breaking off contact with the source of the most precise measurements yet of the universe’s oldest light.
Planck had finished its mission to measure the Big Bang’s remnant radiation, which today constitutes an invisible bath of microwaves permeating the cosmos. This ancient radiation has cooled over time to less than 3 kelvins (degrees above absolute zero). Its precise temperature varies ever so slightly from point to point across the sky.
With 25 times the sensitivity of its predecessor, NASA’s Wilkinson Microwave Anisotropy Probe, Planck was able to identify temperature variations as small as a millionth of a degree. Those temperature fluctuations reflect tiny density