The COBE, WMAP, and Planck observations of the microwave sky have progressively improved our understanding of detailed composition and structure of our universe.
In order to appreciate the full resolution of the Planck data, this card would have to be the size of a poster. How many space missions have studied the cosmic microwave background? CMB as seen by Planck and WMAP . The first space mission specifically designed to study the cosmic microwave background (CMB) was the Cosmic Background Explorer (COBE), launched by NASA in 1989.