Year in Review: Planck refines cosmic history

Satellite hints at slower expansion rate for universe

By Andrew Grant, 21:00 PM December 13, 2013


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 f...

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