Why is the cosmic microwave background so important?
Quick Answer
The cosmic microwave background is the leftover glow from when the universe first became transparent about 380,000 years after the Big Bang. It gives us a snapshot of the infant universe and helps measure its age, composition, and shape.
The Full Story
The cosmic microwave background, or CMB, is faint microwave radiation coming from all directions in space. It was released when the universe cooled enough for electrons and protons to form neutral hydrogen, allowing light to travel freely. That happened about 380,000 years after the Big Bang, and the light has been stretched by expansion into microwaves. Its tiny temperature variations show the seeds of future galaxies. The CMB was discovered accidentally in 1965 by Arno Penzias and Robert Wilson.
Key Facts
YouTube Angle
Suggested video title for this topic:
"The universe still glows with its baby picture."