~13.5 billion years agoReputable sourceEstimated
The First Stars
On the timeline · around ~13.5 billion years ago · Cosmic Dawn
What happened
After recombination the universe entered the 'cosmic dark ages,' with no shining stars. A few hundred million years after the Big Bang, gravity pulled clouds of hydrogen and helium together until they ignited as the first stars. Made almost entirely of those two lightest elements, these first stars forged the first heavier elements in their cores.
Why it matters
The first stars ended the darkness and began enriching the universe with the elements — carbon, oxygen, iron — that make up planets and living things. Astronomers have not yet directly observed them, so their exact timing is still being pinned down.
Sources
- NASA Science. Webb — The Early Universe · Reputable source