98 articles
Electromagnetic follow-up of gravitational-wave events
Electromagnetic follow-up of gravitational-wave events is the search with optical, radio, X-ray, and other telescopes for light from gravitational-wave sources, most successfully for GW170817 in 2017.
Equinox
An equinox, also called an equinoctial point, is either of the two moments each year when the Sun crosses the plane of Earth's equator, in March and September.
Exoplanet
An exoplanet, or extrasolar planet, is a planet orbiting a star other than the Sun. Over 6,000 have been confirmed since the first discovery around a Sun-like star in 1995.
Exoplanet phase curve
An exoplanet phase curve is the measurement of a star-planet system's total brightness as the planet orbits, letting astronomers infer an exoplanet's atmosphere, clouds, winds, and heat distribution without imaging it.
Fast radio burst
A fast radio burst is a millisecond flash of radio emission from cosmological distances, first detected in 2007 and now known to come at least partly from magnetars.
Flux calibration
Flux calibration is the observational procedure in astronomy that converts raw detector counts into physical flux units by comparing observations of standard sources with the science target.
Galaxy spectroscopy
Galaxy spectroscopy is the technique of dispersing the light of whole galaxies into spectra to measure redshifts, internal velocities, and the physical properties of their stars and gas.
Gamma-ray imaging
Gamma-ray imaging is a set of techniques for mapping the direction, energy, and intensity of gamma rays, using coded masks, Compton telescopes, and pair-conversion telescopes.
Geostationary orbit
A geostationary orbit, also called the Clarke Belt or Clarke orbit, is a circular equatorial orbit at 35,786 km where a satellite stays fixed above one spot on Earth.
Geosynchronous orbit
A geosynchronous orbit (GEO) is an Earth orbit with a period of one sidereal day, at about 35,786 km altitude, so satellites stay over a fixed longitude.
Graveyard orbit
A graveyard orbit is an orbit above geostationary altitude where retired satellites are parked at end of mission so they no longer interfere with operating spacecraft.
HI intensity mapping
HI intensity mapping is a radio astronomy technique that maps the large-scale distribution of matter by measuring integrated redshifted 21-cm emission from neutral hydrogen, without resolving individual galaxies.
Integral field spectroscopy
Integral field spectroscopy (IFS) is an astronomical technique that records a spectrum for every position in a two-dimensional field at once, producing a data cube used to map galaxies.
Intensity interferometry
Intensity interferometry is an optical astronomy technique that measures stellar angular diameters by correlating light-intensity fluctuations at separate telescopes, introduced by Hanbury Brown and Twiss in 1956.
Interferometric imaging
Interferometric imaging reconstructs an image of a distant or large object by coherently combining signals from separated antennas or apertures, a technique central to radio astronomy and used in InSAR.
Interplanetary scintillation
Interplanetary scintillation is a radio astronomy technique that measures rapid intensity fluctuations of compact radio sources caused by solar wind density irregularities, used for space weather remote sensing.
JAGB method
The JAGB method, introduced by Madore and Freedman in 2020, measures galaxy distances using carbon-rich asymptotic giant branch stars as near-infrared standard candles and helps calibrate the Hubble constant.
JWST exoplanet atmosphere spectroscopy
JWST exoplanet atmosphere spectroscopy measures how starlight filtered through an exoplanet's atmosphere changes with infrared wavelength, revealing composition, temperature, and clouds on planets outside the Solar System.
JWST infrared spectroscopy
JWST infrared spectroscopy is the observation of infrared spectra by the James Webb Space Telescope, whose four instruments cover 0.6 to 28 micrometers from Lagrange point 2.
K2-18b
K2-18b is a temperate sub-Neptune exoplanet orbiting the red dwarf K2-18 in Leo, about 120 light-years away, discovered in 2015 and known for contested signs of life.
Kepler-186f
Kepler-186f is an Earth-size exoplanet about 500 light-years away in the constellation Cygnus, announced in 2014 as the first Earth-size planet found orbiting a red dwarf within its habitable zone.
Kepler-442b
Kepler-442b, also designated KOI-4742.01, is a super-Earth exoplanet orbiting the K-type star Kepler-442 in Lyra, about 1,200 light-years away, announced in 2015 and ranked among the most Earth-like planets known.
Kepler-452b
Kepler-452b is a candidate super-Earth exoplanet orbiting the Sun-like star Kepler-452 about 1,400 light-years away, announced in 2015 as a possibly rocky planet in the habitable zone, though a 2018 reanalysis left it unconfirmed.
Light curve analysis
Light curve analysis is the set of techniques for measuring and modeling a celestial object's brightness over time, revealing periods, masses, and shapes of variable stars, planets, and asteroids.
Line intensity mapping
Line intensity mapping (LIM) is an observational technique that maps integrated spectral-line emission from unresolved galaxies and the diffuse intergalactic medium, tracing large-scale structure across nearly the universe's entire history.
Long-baseline interferometry
Long-baseline interferometry is an observational astronomy technique that combines signals from telescopes separated by long distances, resolving fine detail in celestial sources at radio, optical, and infrared wavelengths.
Long-slit spectroscopy
Long-slit spectroscopy is an astronomical observing technique that disperses light from a narrow strip of sky, recording a separate spectrum for each point along the slit.
Magnitude (astronomy)
Magnitude, also called star magnitude, is astronomy's logarithmic measure of celestial brightness: five magnitudes equal a 100-fold brightness difference, so brighter objects carry smaller or negative numbers.
Methods of detecting exoplanets
Methods of detecting exoplanets are the observational techniques astronomers use to find planets around other stars. Most detections are indirect, through transit photometry, radial velocity, astrometry, microlensing, and direct imaging.
Multi-object spectroscopy
Multi-object spectroscopy (MOS) is an observational technique in astronomy that records the spectra of many objects at once, using objective prisms, slit masks, or fiber-fed spectrographs, and underpinning large galaxy redshift surveys.