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Astronomy

How the Cosmic Microwave Background Reveals the Universe's Infancy

Quick fact

The cosmic microwave background is a snapshot of the universe at 380,000 years old, and its temperature is now a frigid 2.7 Kelvin (-270°C), but tiny variations in that temperature are the seeds of every galaxy.

Why this is interesting

You can't see the Big Bang, but its faint glow fills the entire sky. If your eyes could detect microwaves, the whole universe would appear to glow from a time when atoms were just being born.