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.

Description: a satellite orbiting the Sun that measures microwave radiation in space
Purpose: to gather information to understand the age and content of the universe
Operated by: European Space Agency
In Operation: 2007-2013
Cool Fact: Planck mapped the entire sky each year, observing some points thousands of times over.

Image credits: main image, © JPL/NASA.