Planck satellite

Planck was a European Space Agency space observatory that mapped the cosmic microwave background across the entire sky from 2009 to 2013, measuring its temperature and polarization.

Cosmic microwave background: The relic radiation released when the early universe became transparent, now observed as microwave light across the sky. Planck mapped this radiation to measure its tiny temperature and polarization variations.
COBE: NASA’s Cosmic Background Explorer satellite, which detected cosmic microwave background anisotropies and measured its spectrum. COBE established the large-scale anisotropies that Planck later mapped in far greater detail.
Lambda-CDM model: The standard cosmological model, combining cold dark matter with a cosmological constant in an expanding universe. Planck’s measurements tightly constrained this model’s parameters and supported its six-parameter form.
Planck 2013 results: The first major cosmological results released from Planck’s observations of the cosmic microwave background. They supplied a precise full-sky temperature map and revised estimates of key cosmological parameters.
Low Frequency Instrument: Planck’s radiometer instrument, which observed the sky at 30, 44, and 70 GHz. Its low-frequency channels helped distinguish Galactic emission from the microwave background.
Wilkinson Microwave Anisotropy Probe: A NASA satellite that mapped the cosmic microwave background from 2001 to 2010. WMAP’s full-sky results preceded Planck and provided a direct comparison of cosmological measurements.
Hubble constant: The present-day rate at which the universe’s expansion speed increases with distance. Planck inferred its value from the early universe, yielding a result lower than several local measurements.
Planck 2015 results: Planck’s second major release of cosmological results, including temperature and polarization analyses. The release added polarization information and refined constraints on the standard cosmological model.
High Frequency Instrument: Planck’s bolometer instrument, which observed the sky from 100 to 857 GHz. Its higher-frequency channels measured the background and foregrounds such as dust emission.
Herschel Space Observatory: An ESA space observatory that studied the universe in far-infrared and submillimeter wavelengths from 2009 to 2013. Herschel and Planck launched together on the same Ariane 5 rocket.

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