Cosmic epoch · Cosmology
Recombination
Cosmology & UniverseEstablished Science
Definition
The moment the cooling Universe let electrons and protons combine into neutral atoms, allowing light to travel freely for the first time.
Scientific overview
As the Universe expanded and cooled to about 3,000 K, electrons and nuclei combined into neutral hydrogen. Space became transparent, and the light released at that moment streams to us today, stretched by expansion into the cosmic microwave background.
Rests on
Predicts
Related discoveries & objects
Knowledge connections
- Depends onThe Big Bang
- PredictsThe Cosmic Microwave Background
- Part of modelThe Lambda-CDM Model
- Related toThe Cosmic Microwave Background
- Required byThe Cosmic Dark Ages
- Required byThe Cosmic Microwave Background
- Required byBaryon Acoustic Oscillations
- Preceded byBig Bang Nucleosynthesis
- Followed byThe Cosmic Dark Ages
Sources & references
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.
- Planck CollaborationESA Planck mission / Planck Collaboration
Cosmic microwave background maps and the cosmological parameters of the ΛCDM model.