OLogy Cards > Planck satellite

What was the universe like right after the Big Bang? To find out, you'd have to look back in time. That was the job of the Planck satellite. As Planck orbited the Sun, it rotated and scanned the sky in all directions, mapping a faint radiation nearly 14 billion light-years away. This radiation, called the cosmic microwave background, is the afterglow of the Big Bang. Planck's data helped reveal the composition of the early universe.