Supernova Cosmology Project

The Supernova Cosmology Project was an international collaboration that measured distant Type Ia supernovae to determine how cosmic expansion changes over time. Its observations contributed to the discovery that the universe’s expansion is accelerating.

Type Ia supernova: A stellar explosion whose peak brightness can be calibrated to estimate its distance. The project used these explosions as distance indicators across the universe.
Saul Perlmutter: An American astrophysicist who led the Supernova Cosmology Project. He organized the collaboration and led its analysis of distant supernovae.
Cosmic acceleration: The observed increase over time in the rate at which the universe expands. The project’s distant-supernova data supplied direct evidence for this acceleration.
Accelerating expansion of the universe: The cosmological observation that the universe’s expansion rate has increased over time. This was the discovery that made the project historically consequential.
High-Z Supernova Search Team: An international collaboration that independently measured distant Type Ia supernovae to test cosmic expansion. Its parallel observations provided an independent route to the same acceleration result.
1990s supernova search: The observing campaigns that sought distant Type Ia supernovae to measure the universe’s expansion history. The project’s defining work began with systematic searches for suitable distant explosions.
Cosmological constant: A constant energy density in space that can drive accelerated expansion in general relativity. It is the simplest theoretical explanation for the expansion acceleration the project measured.
Dark energy equation of state: A parameter describing the relationship between dark energy’s pressure and energy density. After acceleration was established, measuring this parameter became a major follow-up goal.
Standard candle: An astronomical object with a known or calibratable luminosity, used to measure distance. The project inferred supernova distances by comparing calibrated luminosity with observed brightness.
Lawrence Berkeley National Laboratory: A United States national laboratory that conducts research in physical and computational sciences. The project was based there and Perlmutter led it from the laboratory.

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Adam RiessRelated: This independent team reached the same acceleration conclusion in 1998.