Cosmological concept · Cosmology

Dark Energy

Cosmology & UniverseStrong Evidence

Definition

The unknown component driving the accelerating expansion of the Universe, making up roughly 68% of it.

Scientific overview

In 1998 two teams found that cosmic expansion is speeding up, not slowing down. The cause — dubbed dark energy — behaves like an energy of empty space with negative pressure. It dominates the present Universe but its nature is a complete mystery.

Evidence

Type Ia supernovae (1998)
The CMB combined with large-scale structure
Baryon acoustic oscillations

Current measurements

Fraction of the Universe

≈ 68%

Planck Collaboration

Open questions

Is dark energy a cosmological constant, or does it evolve?
Why is its value so small yet non-zero?

Rests on

General Relativity

Related discoveries & objects

The Accelerating Universe

Measured by

Euclid

DESI (Dark Energy Spectroscopic Instrument)

Dark Energy Survey

Related scientists

Saul Perlmutter

Adam Riess

Brian Schmidt

The Cosmological Constant (Λ)

The Expansion of the Universe

Knowledge connections

Required byThe Present Universe
Related toThe Cosmic Horizon
Related toBaryon Acoustic Oscillations
Related toThe Cosmological Constant (Λ)
Related toThe Expansion of the Universe
Part of modelThe Lambda-CDM Model
Depends onGeneral Relativity
Related toThe Accelerating Universe
Studied bySaul Perlmutter
Studied byAdam Riess
Studied byBrian Schmidt
Measured byEuclid
Measured byDESI (Dark Energy Spectroscopic Instrument)
Measured byDark Energy Survey
Required byThe Cosmological Constant (Λ)
Related toThe Lambda-CDM Model
Related toWhite Dwarf
Associated withDark Energy Density (ΩΛ)
Associated withEarly Dark Energy
Associated withEvidence Chains
Associated withZero-Point Energy
Associated withVacuum Energy
Associated withThe Cosmological Constant Problem

Sources & references

Facts on this topic will be cited from these primary and reference sources.

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.
ESAEuropean Space Agency
European missions, observatories, and space science imagery.
DESIDark Energy Spectroscopic Instrument
Spectroscopic redshift survey measuring baryon acoustic oscillations and dark energy.

Quick facts

Type: Cosmological concept
Field: Cosmology
Consensus: Strong Evidence
Part of model: The Lambda-CDM Model

Scientific consensus

Strong Evidence

Strongly supported by multiple independent observations; some details remain open.

Quality & authority

63%

Reviewed

Completeness: Complete
Source coverage: Complete
Citation coverage: Complete
Relationship coverage: Complete
Review coverage: Complete
Image coverage: None

Curated from authoritative sources. See source quality.

Provenance & sources

review 2026.1

Asteria Scientific Review Process · verification: sourced · accurate

Moderate evidencelikely
Dark energy is the name given to whatever drives the observed accelerating expansion of the universe, discovered in 1998; it dominates the universe's energy budget, but its nature remains unknown.
Source: ESA — Planck Collaboration
- Planck 2018 results. VI. Cosmological parameters, Astronomy & Astrophysics 641, A6 (2020)doi:10.1051/0004-6361/201833910
Limitation: The accelerating expansion is well established (2011 Nobel Prize), but the nature of dark energy is unknown — so this is rated moderate, not high, and is not overstated.

Reviewed by the internal Asteria Scientific Review Process — not an external institutional review. See the evidence framework and authority dashboard.

Scientific citations

Real, source-backed references — primary papers first, then datasets and institutional sources. Formatted through the citation engine; nothing is fabricated.

Peer-reviewed paperMeasurements of Omega and Lambda from 42 High-Redshift Supernovae

Saul Perlmutter & et al. · The Astrophysical Journal 517, 565–586 · 1999

The Astrophysical Journal · doi:10.1086/307221

Cite (APA / BibTeX)

Saul Perlmutter & et al. (1999). Measurements of Omega and Lambda from 42 High-Redshift Supernovae. The Astrophysical Journal 517, 565–586. The Astrophysical Journal. https://doi.org/10.1086/307221

@misc{cite:perlmutter-1999,
  title        = {Measurements of Omega and Lambda from 42 High-Redshift Supernovae},
  author       = {Saul Perlmutter and et al.},
  organization = {The Astrophysical Journal},
  howpublished = {The Astrophysical Journal 517, 565–586},
  year         = {1999},
  doi          = {10.1086/307221},
  url          = {https://doi.org/10.1086/307221},
  note         = {Supernova Cosmology Project evidence for dark energy.}
}

Peer-reviewed paperObservational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant

Adam G. Riess & et al. · The Astronomical Journal 116, 1009–1038 · 1998

The Astronomical Journal · doi:10.1086/300499

Cite (APA / BibTeX)

Adam G. Riess & et al. (1998). Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant. The Astronomical Journal 116, 1009–1038. The Astronomical Journal. https://doi.org/10.1086/300499

@misc{cite:riess-1998,
  title        = {Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant},
  author       = {Adam G. Riess and et al.},
  organization = {The Astronomical Journal},
  howpublished = {The Astronomical Journal 116, 1009–1038},
  year         = {1998},
  doi          = {10.1086/300499},
  url          = {https://doi.org/10.1086/300499},
  note         = {Evidence for accelerating cosmic expansion (High-z Supernova Search Team).}
}

Institutional pageDark Energy — NASA Universe

NASA

Cite (APA / BibTeX)

NASA (n.d.). Dark Energy — NASA Universe. NASA. https://science.nasa.gov/

@misc{cite:nasa-cosmo-dark-energy,
  title        = {Dark Energy — NASA Universe},
  organization = {NASA},
  year         = {n.d.},
  url          = {https://science.nasa.gov/},
  note         = {NASA science overview: Dark Energy.}
}

Historical referenceThe Nobel Prize in Physics 2011

2011

The Nobel Prize

Cite (APA / BibTeX)

The Nobel Prize (2011). The Nobel Prize in Physics 2011. The Nobel Prize. https://www.nobelprize.org/prizes/physics/2011/

@misc{cite:nobel-physics-2011,
  title        = {The Nobel Prize in Physics 2011},
  organization = {The Nobel Prize},
  year         = {2011},
  url          = {https://www.nobelprize.org/prizes/physics/2011/},
  note         = {Perlmutter, Schmidt & Riess (accelerating expansion of the universe).}
}

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Sources & references

Facts on this topic will be cited from these primary and reference sources.

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.

ESAEuropean Space Agency

European missions, observatories, and space science imagery.

DESIDark Energy Spectroscopic Instrument

Spectroscopic redshift survey measuring baryon acoustic oscillations and dark energy.

Saul Perlmutter & et al. (1999). Measurements of Omega and Lambda from 42 High-Redshift Supernovae. The Astrophysical Journal 517, 565–586. The Astrophysical Journal. https://doi.org/10.1086/307221 @misc{cite:perlmutter-1999, title = {Measurements of Omega and Lambda from 42 High-Redshift Supernovae}, author = {Saul Perlmutter and et al.}, organization = {The Astrophysical Journal}, howpublished = {The Astrophysical Journal 517, 565–586}, year = {1999}, doi = {10.1086/307221}, url = {https://doi.org/10.1086/307221}, note = {Supernova Cosmology Project evidence for dark energy.} }

Adam G. Riess & et al. (1998). Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant. The Astronomical Journal 116, 1009–1038. The Astronomical Journal. https://doi.org/10.1086/300499 @misc{cite:riess-1998, title = {Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant}, author = {Adam G. Riess and et al.}, organization = {The Astronomical Journal}, howpublished = {The Astronomical Journal 116, 1009–1038}, year = {1998}, doi = {10.1086/300499}, url = {https://doi.org/10.1086/300499}, note = {Evidence for accelerating cosmic expansion (High-z Supernova Search Team).} }

NASA (n.d.). Dark Energy — NASA Universe. NASA. https://science.nasa.gov/ @misc{cite:nasa-cosmo-dark-energy, title = {Dark Energy — NASA Universe}, organization = {NASA}, year = {n.d.}, url = {https://science.nasa.gov/}, note = {NASA science overview: Dark Energy.} }

The Nobel Prize (2011). The Nobel Prize in Physics 2011. The Nobel Prize. https://www.nobelprize.org/prizes/physics/2011/ @misc{cite:nobel-physics-2011, title = {The Nobel Prize in Physics 2011}, organization = {The Nobel Prize}, year = {2011}, url = {https://www.nobelprize.org/prizes/physics/2011/}, note = {Perlmutter, Schmidt & Riess (accelerating expansion of the universe).} }

Dark Energy

Definition

Scientific overview

Evidence

Current measurements

Open questions

Rests on

Related discoveries & objects

Measured by

Related scientists

Related topics

Knowledge connections

Sources & references

Dark Energy

Definition

Scientific overview

Evidence

Current measurements

Open questions

Rests on

Related discoveries & objects

Measured by

Related scientists

Related topics

Knowledge connections

Sources & references