Loading…
Loading contentLoading…
Loading contentThe standard model of cosmology: a flat, expanding Universe dominated by a cosmological constant (Λ) and cold dark matter (CDM).
ΛCDM is the simplest model that fits nearly all cosmological observations — the cosmic microwave background, large-scale structure, the light-element abundances, and the accelerating expansion — with just six parameters. It describes a Universe that is about 68% dark energy, 27% dark matter, and 5% ordinary matter.
Emerged in the late 1990s as dark-energy evidence combined with CMB and structure data; refined to percent-level precision by WMAP and Planck.
| Dark energy (Λ) | ≈ 68% | Planck Collaboration |
| Cold dark matter | ≈ 27% | Planck Collaboration |
| Ordinary matter | ≈ 5% | Planck Collaboration |
| Geometry | Flat (Ω ≈ 1) | Planck Collaboration |
Facts on this topic will be cited from these primary and reference sources.
Cosmic microwave background maps and the cosmological parameters of the ΛCDM model.
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.