Microwaves Map the Early Universe
Most microwave light from space passes through Earth's atmosphere without much interference. Scientists first detected cosmic microwaves from the ground. Astronomers need to use space-based observatories to make the very precise measurements that help map the structure of the early universe.
The ancient history of the universe is written in a faint glow of cosmic background radiation. This first light emerged from the fog of the Big Bang, more than 13 billion years ago.
The Wilkinson Microwave Anisotropy Probe mapped fluctuations in the temperature of matter in the very early universe. Gravity pulled that matter together, creating the seeds of the galaxy clusters we see today.