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Ultraviolet astronomy is the observation of
electromagnetic radiation In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength ...
at
ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
wavelengths between approximately 10 and 320
nanometre 330px, Different lengths as in respect to the Molecule">molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm), or nanometer (American spelling), is a unit of length ...
s; shorter wavelengths—higher energy photons—are studied by
X-ray astronomy X-ray astronomy is an observational branch of astronomy which deals with the study of X-ray observation and detection from astronomical objects. X-radiation is absorbed by the Earth's atmosphere, so instruments to detect X-rays must be taken to ...
and
gamma-ray astronomy Gamma-ray astronomy is a subfield of astronomy where scientists observe and study celestial objects and phenomena in outer space which emit cosmic electromagnetic radiation in the form of gamma rays,Astronomical literature generally hyphena ...
. Ultraviolet light is not visible to the
human eye The human eye is a sensory organ in the visual system that reacts to light, visible light allowing eyesight. Other functions include maintaining the circadian rhythm, and Balance (ability), keeping balance. The eye can be considered as a living ...
. Most of the light at these wavelengths is absorbed by the Earth's atmosphere, so observations at these wavelengths must be performed from the upper atmosphere or from space.


Overview

Ultraviolet line spectrum measurements (
spectroscopy Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectro ...
) are used to discern the chemical composition, densities, and temperatures of the
interstellar medium The interstellar medium (ISM) is the matter and radiation that exists in the outer space, space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as cosmic dust, dust and cosmic rays. It f ...
, and the temperature and composition of hot young stars. UV observations can also provide essential information about the evolution of galaxies. They can be used to discern the presence of a hot
white dwarf A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...
or
main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...
companion in orbit around a cooler star. The ultraviolet
universe The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...
looks quite different from the familiar
star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...
s and galaxies seen in
visible light Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm ...
. Most stars are actually relatively cool objects emitting much of their electromagnetic radiation in the visible or near-
infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...
part of the spectrum. Ultraviolet radiation is the signature of hotter objects, typically in the early and late stages of their
evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...
. In the Earth's sky seen in ultraviolet light, most stars would fade in prominence. Some very young massive stars and some very old stars and galaxies, growing hotter and producing higher-energy radiation near their birth or death, would be visible. Clouds of gas and dust would block the vision in many directions along the
Milky Way The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...
. Space-based solar observatories such as SDO and
SOHO SoHo, short for "South of Houston Street, Houston Street", is a neighborhood in Lower Manhattan, New York City. Since the 1970s, the neighborhood has been the location of many artists' lofts and art galleries, art installations such as The Wall ...
use ultraviolet telescopes (called AIA and EIT, respectively) to view activity on the Sun and its corona. Weather satellites such as the GOES-R series also carry
telescopes A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...
for observing the Sun in ultraviolet. The
Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...
and FUSE have been the most recent major
space telescope A space telescope (also known as space observatory) is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO ...
s to view the near and far UV
spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...
of the sky, though other UV instruments have flown on smaller observatories such as GALEX, as well as
sounding rockets A sounding rocket or rocketsonde, sometimes called a research rocket or a suborbital rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital spaceflight, sub-orbital flight ...
and the
Space Shuttle The Space Shuttle is a retired, partially reusable launch system, reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. ...
. Pioneers in ultraviolet astronomy include George Robert Carruthers, Robert Wilson, and Charles Stuart Bowyer.


Ultraviolet space telescopes

* - Far Ultraviolet Camera/Spectrograph on
Apollo 16 Apollo 16 (April 1627, 1972) was the tenth human spaceflight, crewed mission in the United States Apollo program, Apollo space program, administered by NASA, and the fifth and penultimate to Moon landing, land on the Moon. It was the second o ...
(April 1972) * + ESRO - TD-1A (135-286 nm; 1972–1974) * - Orbiting Astronomical Observatory (#2:1968-73. #3:1972-1981) * - Orion 1 and Orion 2 Space Observatories (#1: 200-380 nm, 1971; #2: 200-300 nm, 1973) * + - Astronomical Netherlands Satellite (150-330 nm, 1974–1976) * + - International Ultraviolet Explorer (115-320 nm, 1978–1996) * - Astron-1 (150-350 nm, 1983–1989) * - Glazar 1 and 2 on Mir (in Kvant-1, 1987–2001) * - FAUST (140-180 nm, in ATLAS-1
Spacelab Spacelab was a reusable laboratory developed by European Space Agency (ESA) and used on certain spaceflights flown by the Space Shuttle. The laboratory comprised multiple components, including a pressurized module, an unpressurized carrier, ...
aboard STS-45 mission, March 1992) * - EUVE (7-76 nm, 1992–2001) * - FUSE (90.5-119.5 nm, 1999–2007) * + - Extreme ultraviolet Imaging Telescope (on
SOHO SoHo, short for "South of Houston Street, Houston Street", is a neighborhood in Lower Manhattan, New York City. Since the 1970s, the neighborhood has been the location of many artists' lofts and art galleries, art installations such as The Wall ...
imaging Sun at 17.1, 19.5, 28.4, and 30.4 nm) * + -
Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...
(various 115-800 nm,1990-1997-) ( STIS 115–1030 nm, 1997–) ( WFC3 200-1700 nm, 2009–) * - Swift Gamma-Ray Burst Mission (170–650 nm, 2004- ) * - Hopkins Ultraviolet Telescope (flew in 1990 and 1995) * - ROSAT XUV (17-210eV) (30-6 nm, 1990–1999) * - Far Ultraviolet Spectroscopic Explorer (90.5-119.5 nm, 1999–2007) * - Galaxy Evolution Explorer (135–280 nm, 2003–2012) * - Hisaki (130-530 nm, 2013 - 2023) * - Lunar-based ultraviolet telescope (LUT) (on Chang'e 3 lunar lander, 245-340  nm, 2013 -) * - Astrosat (130-530 nm, 2015 -) * - Colorado Ultraviolet Transit Experiment - (255-330 nm spectrograph, 2021- ) * - PROBA-3 (CUTE) - (530-588 nm coronagraph, 2024- ) * - Public Telescope (PST) (100-180 nm, Proposed 2015, EU funded study ) * - Viewpoint-1 SpaceFab.US (200-950 nm, Launch planned 2022) See also List of ultraviolet space telescopes


Ultraviolet instruments on planetary spacecraft

* - UVIS ('' Cassini'') - 1997 of (at Saturn from 2004 to 2017) * - MASCS (''
MESSENGER Messenger, Messengers, The Messenger or The Messengers may refer to: People * Courier, a person or company that delivers messages, packages, or mail * Messenger (surname) * Bicycle messenger, a bicyclist who transports packages through cities * M ...
'') - 2004 (at Mercury from 2011 to 2015) * - Alice (''
New Horizons ''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institut ...
'') - 2006 (Pluto flyby in 2015) * - UVS (''Juno'') - 2011 (at Jupiter since 2016) * - IUVS ( MAVEN) - 2013 (at Mars since 2014)


See also

* *


References


External links

* {{Authority control Astronomical imaging Astronomical sub-disciplines
Astronomy Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest includ ...