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Far-infrared astronomy is the branch of
The Earth's atmosphere is opaque over most of the far-infrared, so most far-infrared astronomy is performed by satellites such as the
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 ...
and astrophysics
Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the ...
that deals with objects visible in far-infrared radiation (extending from 30 μm towards submillimeter
Submillimetre astronomy or submillimeter astronomy (see spelling differences) is the branch of observational astronomy that is conducted at submillimetre wavelengths (i.e., terahertz radiation) of the electromagnetic spectrum. Astronomers plac ...
wavelengths around 450 μm).
In the far-infrared, stars are not especially bright, but emission from very cold matter (140 Kelvin or less) can be observed that is not seen at shorter wavelengths. This is due to thermal radiation
Thermal radiation is electromagnetic radiation emitted by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. The emission of energy arises from a combination of electro ...
of interstellar dust
Cosmic dustalso called extraterrestrial dust, space dust, or star dustis dust that occurs in outer space or has fallen onto Earth. Most cosmic dust particles measure between a few molecules and , such as micrometeoroids (30 μm). Cosmic dust can ...
contained in molecular clouds
A molecular cloud—sometimes called a stellar nursery if star formation is occurring within—is a type of interstellar cloud of which the density and size permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, ...
.
These emissions are from dust in circumstellar envelope
A circumstellar envelope (CSE) is a part of a star that has a roughly spherical shape and is not gravitationally bound to the star core. Usually circumstellar envelopes are formed from the dense stellar wind, or they are present before the formati ...
s around numerous old red giant
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The stellar atmosphere, outer atmosphere is inflated and tenuous, making the radius large and the surface t ...
stars. The Bolocam Galactic Plane Survey mapped the galaxy for the first time in the far-infrared.
Telescopes
On 22 January 2014,European Space Agency
The European Space Agency (ESA) is a 23-member International organization, international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 ...
scientists reported the detection, for the first definitive time, of water vapor
Water vapor, water vapour, or aqueous vapor is the gaseous phase of Properties of water, water. It is one Phase (matter), state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from th ...
on the dwarf planet
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be hydrostatic equilibrium, gravitationally rounded, but insufficient to achieve clearing the neighbourhood, orbital dominance like the ...
, Ceres, largest object in the asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...
. The detection was made by using the far-infrared abilities of the Herschel Space Observatory
The Herschel Space Observatory was a space observatory built and operated by the European Space Agency (ESA). It was active from 2009 to 2013, and was the largest infrared telescope ever launched until the launch of the James Webb Space Telesco ...
. The finding is unexpected because comets
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or coma surrounding the nucleus, an ...
, not asteroids
An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
, are typically considered to "sprout jets and plumes". According to one of the scientists, "The lines are becoming more and more blurred between comets and asteroids."
The Earth's atmosphere is opaque over most of the far-infrared, so most far-infrared astronomy is performed by satellites such as the Herschel Space Observatory
The Herschel Space Observatory was a space observatory built and operated by the European Space Agency (ESA). It was active from 2009 to 2013, and was the largest infrared telescope ever launched until the launch of the James Webb Space Telesco ...
, Spitzer Space Telescope
The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003, that was deactivated when operations ended on 30 January 2020. Spitzer was the third space telescope dedicate ...
, IRAS
The Infrared Astronomical Satellite (Dutch language, Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a astronomical survey, survey of the entire night sky at infrared wavelengths. Launched on 25 Janu ...
, and Infrared Space Observatory. Upper-atmosphere observations are also possible, as conducted by the airborne SOFIA
Sofia is the Capital city, capital and List of cities and towns in Bulgaria, largest city of Bulgaria. It is situated in the Sofia Valley at the foot of the Vitosha mountain, in the western part of the country. The city is built west of the Is ...
telescope.
Ground-based observations are limited to submillimetre wavelengths using high-altitude telescopes such as the James Clerk Maxwell Telescope
The James Clerk Maxwell Telescope (JCMT) is a submillimetre-wavelength radio telescope at Mauna Kea Observatory in Hawaii, US. The telescope is near the summit of Mauna Kea at . Its primary mirror is 15 metres (16.4 yards) across: it is the la ...
, the Caltech Submillimeter Observatory, the High Elevation Antarctic Terahertz Telescope and the Submillimeter Array
The Submillimeter Array (SMA) consists of eight diameter radio telescopes arranged as an interferometer for submillimetre astronomy, submillimeter wavelength observations. It is the first purpose-built submillimeter interferometer, constructed a ...
.
See also
*Infrared astronomy
Infrared astronomy is a sub-discipline of astronomy which specializes in the astronomical observation, observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 microm ...
References
{{Authority control Infrared imaging Astronomical imaging Observational astronomy