Extraterrestrial atmosphere explained

The study of extraterrestrial atmospheres is an active field of research,[1] both as an aspect of astronomy and to gain insight into Earth's atmosphere.[2] In addition to Earth, many of the other astronomical objects in the Solar System have atmospheres. These include all the giant planets, as well as Mars, Venus and Titan. Several moons and other bodies also have atmospheres, as do comets and the Sun. There is evidence that extrasolar planets can have an atmosphere. Comparisons of these atmospheres to one another and to Earth's atmosphere broaden our basic understanding of atmospheric processes such as the greenhouse effect, aerosol and cloud physics, and atmospheric chemistry and dynamics.

In September 2022, astronomers were reported to have formed a new group, called "Categorizing Atmospheric Technosignatures" (CATS), to list the results of exoplanet atmosphere studies for biosignatures, technosignatures and related.[3]

Planets

Inner planets

Mercury

See main article: Atmosphere of Mercury. Due to its small size (and thus its small gravity), Mercury has no substantial atmosphere. Its extremely thin atmosphere mostly consists of a small amount of helium and traces of sodium, potassium, and oxygen. These gases derive from the solar wind, radioactive decay, meteor impacts, and breakdown of Mercury's crust.[4] [5] Mercury's atmosphere is not stable and is constantly being refreshed because of its atoms escaping into space as a result of the planet's heat.

Venus

See main article: Atmosphere of Venus. Venus' atmosphere is mostly composed of carbon dioxide. It contains minor amounts of nitrogen and other trace elements, including compounds based on hydrogen, nitrogen, sulphur, carbon, and oxygen. The atmosphere of Venus is much hotter and denser than that of Earth, though shallower. As greenhouse gases warm a lower atmosphere, they cool the upper atmosphere, leading to compact thermospheres.[6] [7] By some definitions, Venus has no stratosphere.

The troposphere begins at the surface and extends up to an altitude of 65 kilometres (an altitude at which the mesosphere has already been reached on Earth). At the top of the troposphere, temperature and pressure reach Earth-like levels. Winds at the surface are a few metres per second, reaching 70 m/s or more in the upper troposphere. The stratosphere and mesosphere extend from 65 km to 95 km in height. The thermosphere and exosphere begin at around 95 kilometres, eventually reaching the limit of the atmosphere at about 220 to 250 km.

The air pressure at Venus' surface is about 92 times that of the Earth. The enormous amount of CO2 in the atmosphere creates a strong greenhouse effect, raising the surface temperature to around 470 °C, hotter than that of any other planet in the Solar System.

Mars

See main article: Atmosphere of Mars and Climate of Mars. The Martian atmosphere is very thin and composed mainly of carbon dioxide, with some nitrogen and argon. The average surface pressure on Mars is 0.6-0.9 kPa, compared to about 101 kPa for Earth. This results in a much lower atmospheric thermal inertia, and as a consequence Mars is subject to strong thermal tides that can change total atmospheric pressure by up to 10%. The thin atmosphere also increases the variability of the planet's temperature. Martian surface temperatures vary from lows of approximately −140 °C (−220 °F) during the polar winters to highs of up to 20 °C (70 °F) in summers.Between the Viking and Mars Global Surveyor missions, Mars saw "Much colder (10-20 K) global atmospheric temperatures were observed during the 1997 versus 1977 perihelion periods" and "that the global aphelion atmosphere of Mars is colder, less dusty, and cloudier than indicated by the established Viking climatology,"[8] with "generally colder atmospheric temperatures and lower dust loading in recent decades on Mars than during the Viking Mission."[9] The Mars Reconnaissance Orbiter, though spanning a much shorter dataset, shows no warming of planetary average temperature, and a possible cooling. "MCS MY 28 temperatures are an average of 0.9 (daytime) and 1.7 K (night- time) cooler than TES MY 24 measurements."[10] Locally and regionally, however, changes in pits in the layer of frozen carbon dioxide at the Martian south pole observed between 1999 and 2001 suggest the south polar ice cap is shrinking. More recent observations indicate that Mars' south pole is continuing to melt. "It's evaporating right now at a prodigious rate," says Michael Malin, principal investigator for the Mars Orbiter Camera.[11] The pits in the ice are growing by about 3 meters (9.8 ft) per year. Malin states that conditions on Mars are not currently conductive to the formation of new ice. A web site has suggested that this indicates a "climate change in progress" on Mars.[12] Multiple studies suggests this may be a local phenomenon rather than a global one.[13]

Colin Wilson has proposed that the observed variations are caused by irregularities in the orbit of Mars.[14] William Feldman speculates the warming could be because Mars might be coming out of an ice age.[15] Other scientists state the warming may be a result of albedo changes from dust storms.[16] [17] The study predicts the planet could continue to warm, as a result of positive feedback.[17]

On June 7, 2018, NASA announced that the Curiosity rover detected a cyclical seasonal variation in atmospheric methane, as well as the presence of kerogen and other complex organic compounds.[18] [19] [20] [21] [22] [23] [24] [25]

Giant Planets

The four outer planets of the Solar System are all giant planets: the gas giants Jupiter and Saturn, and the ice giants Uranus and Neptune. They share some atmospheric commonalities. All have atmospheres that are mostly hydrogen and helium and that blend into the liquid interior at pressures greater than the critical pressure, so that there is no clear boundary between atmosphere and body.

Jupiter

See main article: Atmosphere of Jupiter. Jupiter's upper atmosphere is composed of about 75% hydrogen and 24% helium by mass, with the remaining 1% consisting of other elements. The interior contains denser materials such that the distribution is roughly 71% hydrogen, 24% helium and 5% other elements by mass. The atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur. The outermost layer of the atmosphere contains crystals of frozen ammonia, possibly underlaid by a thin layer of water.

Jupiter is covered with a cloud layer about 50 km deep. The clouds are composed of ammonia crystals and possibly ammonium hydrosulfide. The clouds are located in the tropopause and are arranged into bands of different latitudes, known as tropical regions. These are sub-divided into lighter-hued zones and darker belts. The interactions of these conflicting circulation patterns cause storms and turbulence. The best-known feature of the cloud layer is the Great Red Spot, a persistent anticyclonic storm located 22° south of the equator that is larger than Earth. In 2000, an atmospheric feature formed in the southern hemisphere that is similar in appearance to the Great Red Spot, but smaller in size. The feature was named Oval BA, and has been nicknamed Red Spot Junior.

Observations of the Red Spot Jr. storm suggest Jupiter could be in a period of global climate change.[26] [27] This is hypothesized to be part of an approximately 70 year global climate cycle, characterized by the relatively rapid forming and subsequent slow erosion and merging of cyclonic and anticyclonic vortices in Jupiter's atmosphere. These vortices facilitate the heat exchange between poles and equator. If they have sufficiently eroded, heat exchange is strongly reduced and regional temperatures may shift by as much as 10 K, with the poles cooling down and the equator region heating up. The resulting large temperature differential destabilizes the atmosphere and thereby leads to the creation of new vortices.[28] [29]

Saturn

The outer atmosphere of Saturn consists of about 93.2% hydrogen and 6.7% helium. Trace amounts of ammonia, acetylene, ethane, phosphine, and methane have also been detected. As with Jupiter, the upper clouds on Saturn are composed of ammonia crystals, while the lower level clouds appear to be composed of either ammonium hydrosulfide (NH4SH) or water.

The Saturnian atmosphere is in several ways similar to that of Jupiter. It exhibits a banded pattern similar to Jupiter's, and occasionally exhibits long-lived ovals caused by storms. A storm formation analogous to Jupiter's Great Red Spot, the Great White Spot, is a short-lived phenomenon that forms with a roughly 30-year periodicity. It was last observed in 1990. However, the storms and the band pattern are less visible and active than those of Jupiter, due to the overlying ammonia hazes in Saturn's troposphere.

Saturn's atmosphere has several unusual features. Its winds are among the Solar System's fastest, with Voyager data indicating peak easterly winds of 500 m/s. It is also the only planet with a warm polar vortex, and is the only planet other than Earth where eyewall clouds have been observed in hurricane-like structures.

Uranus

See main article: Atmosphere of Uranus and Climate of Uranus. The atmosphere of Uranus is composed primarily of gas and various ices. It is about 83% hydrogen, 15% helium, 2% methane and traces of acetylene. Like Jupiter and Saturn, Uranus has a banded cloud layer, although this is not readily visible without enhancement of visual images of the planet. Unlike the larger giant planets, the low temperatures in the upper Uranian cloud layer, down to 50 K, causes cloud formation from methane rather than ammonia.

Less storm activity has been observed in the Uranian atmosphere than in those of Jupiter or Saturn, due to the overlying methane and acetylene hazes in its atmosphere making the planet look like a bland, light blue globe. Images taken in 1997 with the Hubble Space Telescope showed storm activity in that part of the atmosphere emerging from the 25-year-long Uranian winter. The general lack of storm activity may be related to the lack of an internal energy generation mechanism for Uranus, a feature unique among the giant planets.[30]

Neptune

The atmosphere of Neptune is similar to that of Uranus. It is about 80% hydrogen, 19% helium, and 1.5% methane. However the weather activity on Neptune is much more active, and its atmosphere is much bluer than that of Uranus. The upper levels of the atmosphere reach temperatures of about 55 K, giving rise to methane clouds in its troposphere, which gives the planet its ultramarine color. Temperatures rise steadily deeper inside the atmosphere. Neptune has extremely dynamic weather systems, including the highest wind speeds in the Solar System, thought to be powered by the flow of internal heat. Typical winds in the banded equatorial region can possess speeds of around 350 m/s (comparable to the speed of sound at room temperature on Earth[31] viz. 343.6 m/s) while storm systems can have winds reaching up to around 900 m/s, in Neptune's atmosphere. Several large storm systems have been identified, including the Great Dark Spot, a cyclonic storm system the size of Eurasia, the Scooter, a white cloud group further south than the Great Dark Spot, and the Wizard's eye/Dark Spot 2, a southern cyclonic storm.

Neptune, the farthest planet from Earth, has increased in brightness since 1980. Neptune's brightness is statistically correlated with its stratospheric temperature. Hammel and Lockwood hypothesize that the change in brightness includes a solar variation component as well as a seasonal component, though they did not find a statistically significant correlation with solar variation. They propose that the resolution of this issue will be clarified by brightness observations in the next few years: forcing by a change in sub-solar latitude should be reflected in a flattening and decline of brightness, while solar forcing should be reflected in a flattening and then resumed rise of brightness.[32]

Other bodies in the Solar System

Natural satellites

Ten of the many natural satellites in the Solar System are known to have atmospheres: Europa, Io, Callisto, Enceladus, Ganymede, Titan, Rhea, Dione, Triton and Earth's Moon. Ganymede and Europa both have very tenuous oxygen atmospheres, thought to be produced by radiation splitting the water ice present on the surface of these moons into hydrogen and oxygen. Io has an extremely thin atmosphere consisting mainly of sulfur dioxide, arising from volcanism and sunlight-driven sublimation of surface sulfur dioxide deposits. The atmosphere of Enceladus is also extremely thin and variable, consisting mainly of water vapor, nitrogen, methane, and carbon dioxide vented from the moon's interior through cryovolcanism. The extremely thin carbon dioxide atmosphere of Callisto is thought to be replenished by sublimation from surface deposits.

Moon

See main article: Atmosphere of the Moon.

Titan

See main article: Atmosphere of Titan. Titan has by far the densest atmosphere of any moon. The Titanian atmosphere is in fact denser than Earth's, with a surface pressure of 147 kPa, one and a half times that of the Earth. The atmosphere is 94.2% nitrogen, 5.65% methane, and 0.099% hydrogen,[33] with the remaining 1.6% composed of other gases such as hydrocarbons (including ethane, diacetylene, methylacetylene, cyanoacetylene, acetylene, propane), argon, carbon dioxide, carbon monoxide, cyanogen, hydrogen cyanide and helium. The hydrocarbons are thought to form in Titan's upper atmosphere in reactions resulting from the breakup of methane by the Sun's ultraviolet light, producing a thick orange smog. Titan has no magnetic field and sometimes orbits outside Saturn's magnetosphere, directly exposing it to the solar wind. This may ionize and carry away some molecules from the top of the atmosphere.

Titan's atmosphere supports an opaque cloud layer that obscures Titan's surface features at visible wavelengths. The haze that can be seen in the adjacent picture contributes to the moon's anti-greenhouse effect and lowers the temperature by reflecting sunlight away from the satellite. The thick atmosphere blocks most visible wavelength light from the Sun and other sources from reaching Titan's surface.

Triton

See main article: Atmosphere of Triton. Triton, Neptune's largest moon, has a tenuous nitrogen atmosphere with small amounts of methane. Tritonian atmospheric pressure is about 1Pa. The surface temperature is at least 35.6 K, with the nitrogen atmosphere in equilibrium with nitrogen ice on Triton's surface.

Triton has increased in absolute temperature by 5% since 1989 to 1998.[34] [35] A similar rise of temperature on Earth would be equal to about 11 °C (20 °F) increase in temperature in nine years. "At least since 1989, Triton has been undergoing a period of global warming. Percentage-wise, it's a very large increase," said James L. Elliot, who published the report.[34]

Triton is approaching an unusually warm summer season that only happens once every few hundred years. Elliot and his colleagues believe that Triton's warming trend could be driven by seasonal changes in the absorption of solar energy by its polar ice caps. One suggestion for this warming is that it is a result of frost patterns changing on its surface. Another is that ice albedo has changed, allowing for more heat from the Sun to be absorbed.[36] Bonnie J. Buratti et al. argue the changes in temperature are a result of deposition of dark, red material from geological processes on the moon, such as massive venting. Because Triton's Bond albedo is among the highest within the Solar System, it is sensitive to small variations in spectral albedo.[37]

Pluto

See main article: Atmosphere of Pluto. Pluto has an extremely thin atmosphere that consists of nitrogen, methane, and carbon monoxide, derived from the ices on its surface.[38] Two models[39] [40] show that the atmosphere does not completely freeze and collapse when Pluto moves further from the Sun on its extremely elliptical orbit. However, some other models do show this. Pluto needs 248 years for one complete orbit, and has been observed for less than one third of that time. It has an average distance of 39 AU from the Sun, hence in-depth data from Pluto is sparse and difficult to gather. Temperature is inferred indirectly for Pluto; when it passes in front of a star, observers note how fast the light drops off. From this, they deduce the density of the atmosphere, and that is used as an indicator of temperature.One such occultation event happened in 1988. Observations of a second occultation on August 20, 2002 suggest that Pluto's atmospheric pressure has tripled, indicating a warming of about 2 °C (3.6 °F),[41] [42] as predicted by Hansen and Paige.[43] The warming is "likely not connected with that of the Earth," says Jay Pasachoff.[44] One astronomer has speculated the warming may be a result of eruptive activity, but it is more likely Pluto's temperature is heavily influenced by its elliptical orbit. It was closest to the Sun in 1989 (perihelion) and has slowly receded since. If it has any thermal inertia, it is expected to warm for a while after it passes perihelion.[45] "This warming trend on Pluto could easily last for another 13 years," says David J. Tholen.[41] It has also been suggested that a darkening of surface ice may also be the cause, but additional data and modeling is needed. Frost distribution on the surface of Pluto is significantly affected by the dwarf planet's high obliquity.[46]

Brown dwarfs

See main article: articles and Brown dwarf. Brown dwarfs have an atmosphere that produces a spectrum from late M-type, over L-type, T-type and finally arriving at Y-dwarf with decreasing temperature. The atmosphere is hydrogen rich and a brown dwarf is 70% hydrogen by mass.[47] Several chemical compounds are present in the atmosphere of brown dwarfs and their importance in shaping the spectrum changes with temperature. Methane and water vapor for example becomes more prominent for colder brown dwarfs.[48]

The physical properties can influence the atmosphere significantly. A low surface gravity of low-mass brown dwarfs or planetary-mass objects can bring the atmosphere in a chemical disequilibrium.[49] Metallicity can influence the amount of methane in the atmosphere and in the extreme case of WISEA 1810−1010 the methane feature is undetectable.

Several models for clouds in the atmosphere of brown dwarfs exist. Near the L/T transition these clouds consists of iron with varying thickness, or of a patchy silicate cloud layer above a thick iron cloud layer.[50] Late T-dwarfs to early Y-dwarfs on the other hand have clouds made from chromium and potassium chloride, as well as several sulfides. At the lowest temperature of some Y-dwarfs water clouds and possibly ammonium dihydrogen phosphate clouds might exist.[51]

Free-floating brown dwarfs rotate faster than Jupiter and studies have inferred the presence of zonal winds. The brown dwarf 2MASS J1047+21 has a rotation period of 1.77 ± 0.04 hours and it has strong winds with speeds of 650±310 m/s proceeding eastwards.[52]

Exoplanets

Several planets outside the Solar System (exoplanets) have been observed to have atmospheres. At the present time, most atmosphere detections are of hot Jupiters or hot Neptunes that orbit very close to their star and thus have heated and extended atmospheres. Observations of exoplanet atmospheres are of two types. First, transmission photometry or spectra detect the light that passes through a planet's atmosphere as it transits in front of its star. Second, the direct emission from a planet atmosphere may be detected by differencing the star plus planet light obtained during most of the planet's orbit with the light of just the star during secondary eclipse (when the exoplanet is behind its star).

The first observation of an extrasolar planetary atmosphere was made in 2001.[53] Sodium in the atmosphere of the planet HD 209458 b was detected during a set of four transits of the planet across its star. Later observations with the Hubble Space Telescope showed an enormous ellipsoidal envelope of hydrogen, carbon and oxygen around the planet. This envelope reaches temperatures of 10,000 K. The planet is estimated to be losing of hydrogen per second. This type of atmosphere loss may be common to all planets orbiting Sun-like stars closer than around 0.1 AU.[54] In addition to hydrogen, carbon, and oxygen, HD 209458 b is thought to have water vapor in its atmosphere.[55] [56] [57] Sodium and water vapour has also been observed in the atmosphere of HD 189733 b,[58] [59] another hot gas giant planet.

In October 2013, the detection of clouds in the atmosphere of Kepler-7b was announced,[60] [61] and, in December 2013, also in the atmospheres of Gliese 436 b and Gliese 1214 b.[62] [63] [64] [65]

In May 2017, glints of light from Earth, seen as twinkling from an orbiting satellite a million kilometres away, were found to be reflected light from ice crystals in the atmosphere.[66] [67] The technology used to determine this may be useful in studying the atmospheres of distant worlds, including those of exoplanets.

Atmospheric composition

In 2001, sodium was detected in the atmosphere of HD 209458 b.

In 2008, water, carbon monoxide, carbon dioxide[68] and methane[69] were detected in the atmosphere of HD 189733 b.

In 2013, water was detected in the atmospheres of HD 209458 b, XO-1b, WASP-12b, WASP-17b, and WASP-19b.[70] [71] [72]

In July 2014, NASA announced finding very dry atmospheres on three exoplanets (HD 189733b, HD 209458b, WASP-12b) orbiting Sun-like stars.[73]

In September 2014, NASA reported that HAT-P-11b is the first Neptune-sized exoplanet known to have a relatively cloud-free atmosphere and, as well, the first time molecules of any kind have been found, specifically water vapor, on such a relatively small exoplanet.[74]

The presence of molecular oxygen may be detectable by ground-based telescopes,[75] and it can be produced by geophysical processes, as well as a byproduct of photosynthesis by life forms, so although encouraging, is not a reliable biosignature.[76] [77] [78] In fact, planets with high concentration of in their atmosphere may be uninhabitable.[78] Abiogenesis in the presence of massive amounts of atmospheric oxygen could be difficult because early organisms relied on the free energy available in redox reactions involving a variety of hydrogen compounds; on an -rich planet, organisms would have to compete with the oxygen for this free energy.[78]

In June 2015, NASA reported that WASP-33b has a stratosphere. Ozone and hydrocarbons absorb large amounts of ultraviolet radiation, heating the upper parts of atmospheres that contain them, creating a temperature inversion and a stratosphere. However, these molecules are destroyed at the temperatures of hot exoplanets, creating doubt if the hot exoplanets could have a stratosphere. A temperature inversion, and stratosphere was identified on WASP-33b caused by titanium oxide, which is a strong absorber of visible and ultraviolet radiation, and can only exist as a gas in a hot atmosphere. WASP-33b is the hottest exoplanet known, with a temperature of 3200°C[79] and is approximately four and a half times the mass of Jupiter.[80] [81]

In February 2016, it was announced that NASA Hubble Space Telescope had detected hydrogen and helium (and suggestions of hydrogen cyanide), but no water vapor, in the atmosphere of 55 Cancri e, the first time the atmosphere of a super-Earth exoplanet was analyzed successfully.[82]

In September 2019, two independent research studies concluded, from Hubble Space Telescope data, that there were significant amounts of water in the atmosphere of exoplanet K2-18b, the first such discovery for a planet within a star's habitable zone.[83] [84] [85]

On 24 Aug 2022, NASA published the discovery by the James Webb Space Telescope of carbon dioxide in the atmosphere of WASP-39b.[86] [87]

Missing Methane Problem

Carbon monoxide should be replaced by methane as the dominant carbon-bearing molecule in the atmosphere of exoplanets at temperatures below 1000 K. While methane is detected in solar system objects, young directly imaged exoplanets and in free-floating brown dwarfs (T/Y-dwarfs), it is rarely detected in transiting exoplanets. This observation was dubbed the Missing Methane Problem. Some studies tried to explain this with a depletion of methane. The most solid detection of methane is in the atmosphere of the warm Jupiter (825 K) WASP-80b, which was detected with NIRCam. This detection is in agreement with models that do not require a strong methane depletion. This detection suggested that other instruments did not have the wavelength coverage or precision needed to detect methane.[88] Non-detection of methane in HD 209458b on the other hand showed that the missing methane problem cannot be resolved for all exoplanets with JWST and an explanation for the missing methane is required. Explanations often involve a high metallicity and a low carbon-to-oxygen ratio.[89]

A similar problem exists for the detection of ammonia.[90] Methane and ammonia is detected in free-floating Y-dwarfs (Teff<400 K), such as WISE 0359−5401. Transiting exoplanets on the other hand do rarely show ammonia. For example the ~300 K exoplanets K2-18b showed a depletion of methane and ammonia[91] and more recent observations with NIRISS and NIRSpec was able to resolve the methane problem for K2-18b. The observations showed strong absorption due to methane, but was not able to detect any ammonia in K2-18b.[92] The research team explained this missing ammonia with an ocean that absorbs certain gases. Other researchers are more cautious about this ocean claim.[93] One problem is that ammonia and methane absorption overlap in the near-infrared. Ammonia absorption could be mistaken as methane and mid-infrared detections of ammonia are much clearer, such as in WISE 0359−5401 with MIRI.

Another problem exists for phosphine (PH3) which is a strong absorber in Jupiter, but does not appear in similar cold free-floating T- and Y-dwarfs, such as WISE 0855−0714, WISE 0359−5401, WISE 1828+2650 and 2MASS 0415−0935. One explanation is that the behaviour of phosphorus in the atmosphere of brown dwarfs to giant exoplanets is not well understood.[94]

Atmospheric circulation

See also: Exometeorology. The atmospheric circulation of planets that rotate more slowly or have a thicker atmosphere allows more heat to flow to the poles which reduces the temperature differences between the poles and the equator.[95]

Winds

Winds of over 2 km/s—which is seven times the speed of sound or 20 times faster than the fastest ever winds known on Earth—have been discovered flowing around the planet HD 189733b.[96] [97]

Clouds

The composition of clouds in gas giants depend on temperature. A cloud layer does "sink" with decreasing temperature. This way one exoplanet might have a cloud layer at a higher pressure (lower altitude) compared to a warmer exoplanet. High altitude clouds often block light coming from deeper layers of the atmosphere, including chemical absorption features. Weaker than normal absorption features is the main method to detect the presence of clouds via transmission spectroscopy.[98] In some cases the absorption from the clouds can be directly observed, such as quartz-clouds on WASP-17b with JWST.[99] One way to predict the appearance of a gas giant is the Sudarsky's gas giant classification. But this classification scheme is over two decades old and more recent models sometimes predict thin clouds for class III and class IV. This classification also does not consider ultra-hot Jupiters, which do have nightside clouds.[100] Relative cloud-free atmospheres also exist.[101]

Similar to brown dwarfs the composition at hotter temperature (class V or >900 K) is a thick iron cloud deck with silicate clouds (quartz, corundum, fosterite and/or enstatite) on top. This top layer can be patchy and cover 70-90% of the planet.[102] At lower temperatures (class III-IV or 400-1,300 K) the iron and silicate clouds sink deep into the atmosphere and thin clouds made of chromium, potassium chloride and especially sulfides (manganese sulfide, sodium sulfide and zink sulfide) become more important. At low temperatures (class II <400 K) water clouds and possibly ammonium dihydrogen phosphate clouds might exist. But lower layers of clouds of sulfides and potassium chloride should exist at this temperature. Jupiter and Saturn-like atmospheres (class I or <150 K) are dominated by ammonia clouds, but lower layers of water clouds might exist.[103]

A newer type of exoplanets, called ultra-hot Jupiters have a temperature above 2,000 K and have a cloud-free dayside with molecules often dissociated into atoms or ions. A wide variety of atomic lines were detected in the transmission spectra of the ultra-hot Jupiters.[104] [105] [106] The nightside can be up to 2,500 K colder than the dayside and in WASP-18b this temperature drop causes clouds to form at the terminator. At the equator of the terminator, which forms clouds on WASP-18b (in the west seen from the dayside) the cloud top is made of thin layers dominated by titanium dioxide, corundum (aluminium oxide), perovskite (calcium titanate) and iron. The majority of the vertical portion of the cloud is made up of clouds of enstatite, fosterite, periclase (magnesium oxide), quartz, iron and inclusion of other material. The cloud bottom changes from quartz dominated, to iron, then corundum and then perovskite dominated. These bottom layers have large particle sizes of about 60 μm. At other positions of the terminator these clouds change their composition and particle size. The cloud-free dayside and the cloudy terminator/nightside would make these ultra-hot Jupiters look similar to an eyeball planet.

In October 2013, the detection of clouds in the atmosphere of Kepler-7b was announced, and, in December 2013, also in the atmospheres of GJ 436 b and GJ 1214 b.

Precipitation

Precipitation in the form of liquid (rain) or solid (snow) varies in composition depending on atmospheric temperature, pressure, composition, and altitude. Hot atmospheres could have iron rain,[107] molten-glass rain,[108] and rain made from rocky minerals such as enstatite, corundum, spinel, and wollastonite.[109] Deep in the atmospheres of gas giants, it could rain diamonds[110] and helium containing dissolved neon.[111]

Abiotic oxygen

There are geological and atmospheric processes that produce free oxygen, so the detection of oxygen is not necessarily an indication of life.[112]

The processes of life result in a mixture of chemicals that are not in chemical equilibrium but there are also abiotic disequilibrium processes that need to be considered. The most robust atmospheric biosignature is often considered to be molecular oxygen and its photochemical byproduct ozone . The photolysis of water by UV rays followed by hydrodynamic escape of hydrogen can lead to a build-up of oxygen in planets close to their star undergoing runaway greenhouse effect. For planets in the habitable zone, it was thought that water photolysis would be strongly limited by cold-trapping of water vapour in the lower atmosphere. However, the extent of H2O cold-trapping depends strongly on the amount of non-condensible gases in the atmosphere such as nitrogen N2 and argon. In the absence of such gases, the likelihood of build-up of oxygen also depends in complex ways on the planet's accretion history, internal chemistry, atmospheric dynamics, and orbital state. Therefore, oxygen, on its own, cannot be considered a robust biosignature.[113] The ratio of nitrogen and argon to oxygen could be detected by studying thermal phase curves[114] or by transit transmission spectroscopy measurement of the spectral Rayleigh scattering slope in a clear-sky (i.e. aerosol-free) atmosphere.[115]

Life

See main article: Planetary habitability and Biosignature.

Methane

Detection of methane in astronomical bodies is of interest to science and technology, as it may be evidence of extraterrestrial life (biosignature),[116] [117] it may help provide organic ingredients for life to form,[116] [118] [119] and also, methane could be used as a fuel or rocket propellant for future robotic and crewed missions in the Solar System.[120] [121]

See also

Further reading

Notes and References

  1. Web site: Department of Atmospheric Science, University of Washington . 2007-05-24.
  2. Web site: NASA GISS: Research in Planetary Atmospheres . 2007-05-24 . dead . https://web.archive.org/web/20070516075433/http://www.giss.nasa.gov/research/planets/ . 2007-05-16 .
  3. News: Gertner . Jon . The Search for Intelligent Life Is About to Get a Lot More Interesting - There are an estimated 100 billion galaxies in the universe, home to an unimaginable abundance of planets. And now there are new ways to spot signs of life on them. . 15 September 2022 . . 15 September 2022 .
  4. Web site: Thin Atmosphere of Mercury, Formation and Composition - Windows to the Universe. www.windows.ucar.edu. 2007-05-25. https://web.archive.org/web/20100327214903/http://www.windows.ucar.edu/tour/link=/mercury/Atmosphere/atmosphere.html. 2010-03-27. dead.
  5. Web site: ESA Science & Technology: Mercury Atmosphere. https://archive.today/20120721222817/http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=31275. dead. 21 July 2012. 21 July 2012. esa.int.
  6. J. . Picone . J. . Lean . Judith Lean . Global Change in the Thermosphere: Compelling Evidence of a Secular Decrease in Density . 2005 . 225–227 . 2005 NRL Review.
  7. H. . etal . Lewis . Response of the Space Debris Environment to Greenhouse Cooling . April 2005 . 243 . Proceedings of the 4th European Conference on Space Debris . 587 . 2005ESASP.587..243L .
  8. An intercomparison of ground-based millimeter, MGS TES, and Viking atmospheric temperature measurements: Seasonal and interannual variability of temperatures and dust loading in the global Mars atmosphere . Journal of Geophysical Research . Clancy . R. . 105 . 4 . April 25, 2000 . 9553–9571. 2000JGR...105.9553C . 10.1029/1999JE001089 . free .
  9. Mars Reconnaissance Orbiter Mars Color Imager (MARCI): Instrument Description, Calibration, and Performance . Journal of Geophysical Research . Bell, J . 140643009 . etal . 114 . 8 . E08S92 . August 28, 2009 . 10.1029/2008je003315 . 2009JGRE..114.8S92B. free .
  10. Bandfield, J. L. . etal . Radiometric Comparison of Mars Climate Sounder and Thermal Emission Spectrometer Measurements . Icarus . 225 . 1 . 2013 . 28–39 . 10.1016/j.icarus.2013.03.007 . 2013Icar..225...28B.
  11. Web site: MGS sees changing face of Mars . Reddy . Francis . . 2005-09-23 . 2007-02-22.
  12. Web site: Orbiter's Long Life Helps Scientists Track Changes on Mars . 2005-09-20 . . 2007-05-09 . dead . https://web.archive.org/web/20070430085506/http://mpfwww.jpl.nasa.gov/mgs/newsroom/20050920a.html . April 30, 2007 .
  13. Liu, J. . Richardson, M. . 7433260 . An assessment of the global, seasonal, and interannual spacecraft record of Martian climate in the thermal infrared . Journal of Geophysical Research . 108 . 8 . 5089 . August 2003 . 10.1029/2002je001921 . 2003JGRE..108.5089L. free .
  14. Web site: Mars Melt Hints at Solar, Not Human, Cause for Warming, Scientist Says . https://web.archive.org/web/20070302094717/http://news.nationalgeographic.com/news/2007/02/070228-mars-warming.html . dead . March 2, 2007 . Ravilious . . Kate . 2007-03-28 . 2007-05-09.
  15. Web site: Mars Emerging from Ice Age, Data Suggest . . 2003-12-08 . 2007-05-10.
  16. Lori K. . Fenton . etal . Global warming and climate forcing by recent of albedo changes on Mars . 2007-04-05 . . 446 . 7136 . 10.1038/nature05718 . 646–649 . 2007-05-09 . 17410170 . 2007Natur.446..646F . 4411643 . dead . https://web.archive.org/web/20070708011126/http://humbabe.arc.nasa.gov/~fenton/pdf/fenton/nature05718.pdf . 2007-07-08 .
  17. Web site: Mars Warming Due to Dust Storms, Study Finds . https://web.archive.org/web/20070409184218/http://news.nationalgeographic.com/news/2007/04/070404-mars-warming.html . dead . April 9, 2007 . Ravilious . . Kate . 2007-04-04 . 2007-05-19.
  18. Web site: Brown . Dwayne . Wendel . JoAnna . Steigerwald . Bill . Jones . Nancy . Good . Andrew . Release 18-050 - NASA Finds Ancient Organic Material, Mysterious Methane on Mars . June 7, 2018 . . June 7, 2018 .
  19. Web site: NASA . Ancient Organics Discovered on Mars - video (03:17) . https://ghostarchive.org/varchive/youtube/20211221/a0gsz8EHiNc . 2021-12-21 . live. June 7, 2018 . . June 7, 2018 .
  20. Web site: Wall . Mike . Curiosity Rover Finds Ancient 'Building Blocks for Life' on Mars . June 7, 2018 . . June 7, 2018 .
  21. News: Chang . Kenneth . Life on Mars? Rover's Latest Discovery Puts It 'On the Table' - The identification of organic molecules in rocks on the red planet does not necessarily point to life there, past or present, but does indicate that some of the building blocks were present. . June 7, 2018 . . June 8, 2018 .
  22. Voosen . Paul . NASA rover hits organic pay dirt on Mars . June 7, 2018 . . June 7, 2018 . 10.1126/science.aau3992 . 115442477 .
  23. ten Kate . Inge Loes . Organic molecules on Mars . June 8, 2018 . . 360 . 6393 . 1068–1069 . 10.1126/science.aat2662. 29880670 . 2018Sci...360.1068T . 195666358 .
  24. Webster, Christopher R.. etal. Background levels of methane in Mars' atmosphere show strong seasonal variations . June 8, 2018 . . 360 . 6393 . 1093–1096 . 10.1126/science.aaq0131. 29880682. 2018Sci...360.1093W. free .
  25. Eigenbrode, Jennifer L.. etal. Organic matter preserved in 3-billion-year-old mudstones at Gale crater, Mars . June 8, 2018 . . 360 . 6393 . 1096–1101 . 10.1126/science.aas9185. 29880683 . 2018Sci...360.1096E. free . 10044/1/60810 . free .
  26. Velocities and Temperatures of Jupiter's Great Red Spot and the New Red Oval and Implications for Global Climate Change . APS Division of Fluid Dynamics Meeting Abstracts . 59 . FG.005 . 2006APS..DFD.FG005M . Marcus. Philip S. . etal . November 2006.
  27. Web site: New Storm on Jupiter Hints at Climate Change . Goudarzi . Sara . . 2006-05-04 . 2007-05-09.
  28. Prediction of a global climate change on Jupiter . Marcus . Philip S. . 2004-04-22 . . 428 . 6985 . 828–831 . 2007-05-09 . 10.1038/nature02470 . 15103369 . 2004Natur.428..828M . 4412876 . dead . https://web.archive.org/web/20070416201459/http://www.me.berkeley.edu/cfd/people/marcus/nature02470.pdf . 2007-04-16 .
  29. Web site: Researcher predicts global climate change on Jupiter as giant planet's spots disappear . Yang . Sarah . 2004-04-21 . . 2007-05-09.
  30. Web site: Uranus' Atmosphere . 2007-05-23.
  31. Web site: Speed of sound calculation.
  32. Web site: AGU - American Geophysical Union. AGU. 2007-05-10. 2012-11-02. https://web.archive.org/web/20121102124827/http://www.agu.org/pubs/crossref/2007/2006GL028764.shtml. dead.
  33. Catling, David C.; Kasting, James F. (10 May 2017). Atmospheric Evolution on Inhabited and Lifeless Worlds (1 ed.). Cambridge University Press. .
  34. Web site: MIT researcher finds evidence of global warming on Neptune's largest moon . 1998-06-24 . . 2007-05-10.
  35. Global warming on Triton . Elliot . James L. . James L. Elliot . etal . . 393 . 6687 . 1998-06-25 . 765–767 . 2007-05-10 . 10.1038/31651 . 1998Natur.393..765E . 40865426. dead . https://web.archive.org/web/20110520042510/http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=TRD&recid=A9833826AH&q=&uid=&setcookie=yes . 2011-05-20 .
  36. Web site: Global Warming Detected on Triton . 1998-05-28 . Scienceagogo.com . 2007-05-10.
  37. Does global warming make Triton blush? . Buratti . Bonnie J. . etal . . 397 . 6716 . 1999-01-21 . 219–20 . 10.1038/16615 . 9930696 . 1999Natur.397..219B . free .
  38. Web site: Nitrogen in Pluto's Atmosphere. Ken Croswell. 1992. 2007-04-27.
  39. Seasonal Nitrogen Cycles on Pluto . Hansen . C . Paige . D . Icarus . Apr 1996 . 10.1006/icar.1996.0049 . 1996Icar..120..247H . 120 . 2 . 247–265. 10.1.1.26.4515 .
  40. Evidence That Pluto's Atmosphere Does Not Collapse From Occultations Including The 2013 May 04 Event . Olkin . C . Young . L . etal . Icarus . March 2014 . 10.1016/j.icarus.2014.03.026 . 2015Icar..246..220O . 246 . 220–225. free . 10261/167246 . free .
  41. Web site: Global Warming on Pluto Puzzles Scientists . Britt . Roy . 2002-10-09 . . 2007-05-09.
  42. The recent expansion of Pluto's atmosphere . Elliot . James L. . James L. Elliot . etal . . 424 . 6945 . 165–168 . 2003-07-10 . 2007-05-10. 10.1038/nature01762. 12853949 . https://web.archive.org/web/20070417165057/http://occult.mit.edu/publications/Elliot2003Nature424.165.pdf . 2007-04-17. 2003Natur.424..165E . 10512970 .
  43. Web site: Staff . Postcards from Pluto . . April 2014 . March 1, 2015.
  44. Web site: Pluto is undergoing global warming, researchers find . . 2002-10-09 . 2007-05-09.
  45. Web site: Pluto's atmosphere does not collapse . Lakdawalla . E. . April 17, 2013 . November 11, 2014 .
  46. Seasonal Nitrogen Cycles on Pluto . Hansen . Candice J. . Paige, David A. . April 1996 . . 120 . 2 . 247–265. 10.1006/icar.1996.0049 . 1996Icar..120..247H. 10.1.1.26.4515.
  47. Web site: Brown Dwarf - an overview ScienceDirect Topics . 2023-10-16 . www.sciencedirect.com . The brown dwarfs are distinguished from white dwarfs first by their very cool surface temperatures and second by the fact that their internal composition is practically unchanged from the time of formation; that is, it is about 71% hydrogen by mass..
  48. Marley . Mark S. . Saumon . Didier . Visscher . Channon . Lupu . Roxana . Freedman . Richard . Morley . Caroline . Fortney . Jonathan J. . Seay . Christopher . Smith . Adam J. R. W. . Teal . D. J. . Wang . Ruoyan . 2021-10-01 . The Sonora Brown Dwarf Atmosphere and Evolution Models. I. Model Description and Application to Cloudless Atmospheres in Rainout Chemical Equilibrium . The Astrophysical Journal . 920 . 2 . 85 . 10.3847/1538-4357/ac141d . 2107.07434 . 2021ApJ...920...85M . 0004-637X . See Figure 3 to 7. free .
  49. Zahnle . Kevin J. . Marley . Mark S. . 2014-12-01 . Methane, Carbon Monoxide, and Ammonia in Brown Dwarfs and Self-Luminous Giant Planets . The Astrophysical Journal . 797 . 1 . 41 . 10.1088/0004-637X/797/1/41 . 1408.6283 . 2014ApJ...797...41Z . 0004-637X. free .
  50. Vos . Johanna M. . Burningham . Ben . Faherty . Jacqueline K. . Alejandro . Sherelyn . Gonzales . Eileen . Calamari . Emily . Bardalez Gagliuffi . Daniella . Visscher . Channon . Tan . Xianyu . Morley . Caroline V. . Marley . Mark . Gemma . Marina E. . Whiteford . Niall . Gaarn . Josefine . Park . Grace . 2023-02-01 . Patchy Forsterite Clouds in the Atmospheres of Two Highly Variable Exoplanet Analogs . The Astrophysical Journal . 944 . 2 . 138 . 10.3847/1538-4357/acab58 . 2212.07399 . 2023ApJ...944..138V . 0004-637X. free .
  51. Morley . Caroline V. . Fortney . Jonathan J. . Marley . Mark S. . Visscher . Channon . Saumon . Didier . Leggett . S. K. . 2012-09-01 . Neglected Clouds in T and Y Dwarf Atmospheres . The Astrophysical Journal . 756 . 2 . 172 . 10.1088/0004-637X/756/2/172 . 0004-637X. 1206.4313 . 2012ApJ...756..172M . 118398946 .
  52. Allers . Katelyn. N. . Vos . Johanna M. . Biller . Beth A. . Williams . Peter. K. G. . 2020-04-01 . A measurement of the wind speed on a brown dwarf . Science . 368 . 6487 . 169–172 . 10.1126/science.aaz2856 . 32273464 . 2020Sci...368..169A . 264645727 . 0036-8075. 20.500.11820/06e2e379-467a-456f-956c-b37912b8d95a . free .
  53. Charbonneau. David. etal. 2002. Detection of an Extrasolar Planet Atmosphere. The Astrophysical Journal. 568. 1. 377–384. astro-ph/0111544. 2002ApJ...568..377C. 10.1086/338770. 14487268.
  54. astro-ph/0312384 . Hébrard . G. . Lecavelier des Étangs . A. . Vidal-Madjar . A. . Désert . J. -M. . Ferlet . R. . Evaporation rate of hot Jupiters and formation of Chthonian planets . 2003 .
  55. http://www.space.com/scienceastronomy/070410_water_exoplanet.html Water Found in Extrasolar Planet's Atmosphere
  56. https://www.reuters.com/article/scienceNews/idUSN1043498020070411 Signs of water seen on planet outside solar system
  57. http://www.lowell.edu/press_room/releases/recent_releases/extrasolar_water.html Water Identified in Extrasolar Planet Atmosphere
  58. Khalafinejad . S. . Essen . C. von . Hoeijmakers . H. J. . Zhou . G. . Klocová . T. . Schmitt . J. H. M. M. . Dreizler . S. . Lopez-Morales . M. . Husser . T.-O. . 2017-02-01 . Exoplanetary atmospheric sodium revealed by orbital motion . Astronomy & Astrophysics . en . 598 . A131 . 10.1051/0004-6361/201629473 . 0004-6361. 1610.01610 . 2017A&A...598A.131K . 55263138 .
  59. Web site: Press Release: NASA's Spitzer Finds Water Vapor on Hot, Alien Planet. caltech.edu. 2007-07-22. 2007-07-15. https://web.archive.org/web/20070715120124/http://www.spitzer.caltech.edu/Media/releases/ssc2007-12/release.shtml. dead.
  60. Web site: Chu . Jennifer . Scientists generate first map of clouds on an exoplanet . October 2, 2013 . . January 2, 2014 .
  61. Demory, Brice-Olivier . etal . Inference of Inhomogeneous Clouds in an Exoplanet Atmosphere . September 30, 2013 . The Astrophysical Journal. 1309.7894 . 2013ApJ...776L..25D . 10.1088/2041-8205/776/2/L25 . 776 . 2 . L25. 701011 .
  62. Web site: Harrington . J.D. . Weaver . Donna . Villard . Ray . Release 13-383 - NASA's Hubble Sees Cloudy Super-Worlds With Chance for More Clouds . December 31, 2013 . . January 1, 2014 .
  63. Moses . Julianne . Extrasolar planets: Cloudy with a chance of dustballs . January 1, 2014 . . 505 . 7481 . 31–32 . 10.1038/505031a . 2014Natur.505...31M . 24380949. 4408861 .
  64. Knutson, Heather . etal . A featureless transmission spectrum for the Neptune-mass exoplanet GJ 436b . January 1, 2014 . . 505 . 7481 . 66–68 . 10.1038/nature12887 . 1401.3350 . 2014Natur.505...66K . 24380953. 4454617 .
  65. Kreidberg, Laura . etal . Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b . January 1, 2014 . . 505 . 7481 . 69–72 . 10.1038/nature12888 . 1401.0022 . 2014Natur.505...69K . 24380954. 4447642 .
  66. News: St. Fleur . Nicholas . Spotting Mysterious Twinkles on Earth From a Million Miles Away . 19 May 2017 . . 20 May 2017 .
  67. Marshak . Alexander . Várnai . Tamás . Kostinski . Alexander . Terrestrial glint seen from deep space: oriented ice crystals detected from the Lagrangian point . 15 May 2017 . . 44 . 10 . 5197 . 10.1002/2017GL073248 . 2017GeoRL..44.5197M . 109930589 . 11603/13118 . free .
  68. 10.1088/0004-637X/690/2/L114. 0812.1844. Molecular Signatures in the Near Infrared Dayside Spectrum of HD 189733b. The Astrophysical Journal. 690. 2. L114. 2009. Swain . M. R.. Vasisht . G.. Tinetti . G.. Bouwman . J.. Chen . P. . Yung . Y.. Deming . D.. Deroo . P.. 2009ApJ...690L.114S. 10720307.
  69. http://www.nasa.gov/mission_pages/hubble/science/hst_img_20080319.html NASA – Hubble Finds First Organic Molecule on an Exoplanet
  70. Web site: Hubble Traces Subtle Signals of Water on Hazy Worlds . 3 December 2013 . NASA. 4 December 2013 .
  71. 10.1088/0004-637X/774/2/95. 1302.1141 . 2013ApJ...774...95D. Infrared Transmission Spectroscopy of the Exoplanets HD 209458b and XO-1b Using the Wide Field Camera-3 on the Hubble Space Telescope. The Astrophysical Journal. 774. 2. 95. 2013. Deming . D. . Wilkins . A. . McCullough . P. . Burrows . A. . Fortney . J. J. . Agol . E. . Dobbs-Dixon . I. . Madhusudhan . N. . Crouzet . N. . Desert . J. M. . Gilliland . R. L. . Haynes . K. . Knutson . H. A. . Line . M. . Magic . Z. . Mandell . A. M. . Ranjan . S. . Charbonneau . D. . Clampin . M. . Seager . S. . Showman . A. P. . 10960488 .
  72. 10.1088/0004-637X/779/2/128. 2013ApJ...779..128M. 1310.2949 . Exoplanet Transit Spectroscopy Using WFC3: WASP-12 b, WASP-17 b, and WASP-19 b. The Astrophysical Journal. 779. 2. 128. 2013. Mandell . A. M. . Haynes . K. . Sinukoff . E. . Madhusudhan . N. . Burrows . A. . Deming . D. . 52997396.
  73. Web site: Harrington . J.D. . Villard . Ray . RELEASE 14–197 – Hubble Finds Three Surprisingly Dry Exoplanets . 24 July 2014 . . 25 July 2014 .
  74. Web site: Clavin . Whitney . Chou . Felicia . Weaver . Donna . Villard . Ray . Johnson . Michele . NASA Telescopes Find Clear Skies and Water Vapor on Exoplanet . 24 September 2014 . . 24 September 2014 .
  75. 10.1088/0004-637X/758/1/13. 1206.0558. 2012ApJ...758...13K . Can Ground-based Telescopes Detect the Oxygen 1.27 μm Absorption Feature as a Biomarker in Exoplanets?. The Astrophysical Journal. 758. 1. 13. 2012. Kawahara . H. . Matsuo . T. . Takami . M. . Fujii . Y. . Kotani . T. . Murakami . N. . Tamura . M. . Guyon . O. . 119261987.
  76. 10.1038/srep13977. 4564821 . 5 . Titania may produce abiotic oxygen atmospheres on habitable exoplanets . 2015 . Scientific Reports . 13977 . Narita . Norio. 26354078 . 1509.03123 . 2015NatSR...513977N . free .
  77. astro-ph/0308324. A New Family of Planets ? "Ocean Planets". Alain. Léger. 2004. 10.1016/j.icarus.2004.01.001. Icarus. 169. 2. 499–504. 2004Icar..169..499L. 119101078.
  78. 10.1089/ast.2014.1231 . 2015AsBio..15..119L . 4323125 . 15 . Extreme water loss and abiotic O2 buildup on planets throughout the habitable zones of M dwarfs . 2015 . Astrobiology . 119–43 . Luger . R . Barnes . R . 2 . 25629240 . 1411.7412 .
  79. Web site: Hottest planet is hotter than some stars. 2015-06-12.
  80. Web site: NASA's Hubble Telescope Detects 'Sunscreen' Layer on Distant Planet. 2015-06-11. 2015-06-11.
  81. Spectroscopic Evidence for a Temperature Inversion in the Dayside Atmosphere of the Hot Jupiter WASP-33b . 1505.01490 . 2015-05-06. Korey. Haynes. Avi M.. Mandell. Nikku. Madhusudhan. Drake. Deming. Heather. Knutson. 2015ApJ...806..146H . 10.1088/0004-637X/806/2/146 . 806 . 2 . The Astrophysical Journal . 146. 35485407 .
  82. Web site: Staff . First detection of super-earth atmosphere . 16 February 2016 . . 17 February 2016 .
  83. News: Ghosh . Pallab . Water found on 'habitable' planet . . 11 September 2019 . 12 September 2019 .
  84. Web site: Greshko . Michael . Water found on a potentially life-friendly alien planet . https://web.archive.org/web/20190911201003/https://www.nationalgeographic.com/science/2019/09/first-water-found-in-habitable-exoplanets-atmosphere-hubble-kepler-k2-18b/ . dead . September 11, 2019 . . 11 September 2019 . 12 September 2019 .
  85. Tsiaras, Angelo . et al. . Water vapour in the atmosphere of the habitable-zone eight-Earth-mass planet K2-18 b . . 1086–1091 . 11 September 2019 . 10.1038/s41550-019-0878-9 . 1909.05218 . 2019NatAs...3.1086T . 3 . 12 . 202558393 .
  86. Web site: 2022-08-26 . The James Webb telescope spotted CO2 in an exoplanet's atmosphere . 2022-08-28 . Science News . en-US.
  87. The JWST Transiting Exoplanet Community Early Release Science Team . Ahrer . Eva-Maria . Alderson . Lili . Batalha . Natalie M. . Batalha . Natasha E. . Bean . Jacob L. . Beatty . Thomas G. . Bell . Taylor J. . Benneke . Björn . Berta-Thompson . Zachory K. . Carter . Aarynn L. . Crossfield . Ian J. M. . Espinoza . Néstor . Feinstein . Adina D. . Fortney . Jonathan J. . 2023 . Identification of carbon dioxide in an exoplanet atmosphere . Nature . 614 . 7949 . 649–652 . 10.1038/s41586-022-05269-w . 36055338 . 9946830 . 2208.11692 . 2023Natur.614..649J .
  88. Bell . Taylor J. . Welbanks . Luis . Schlawin . Everett . Line . Michael R. . Fortney . Jonathan J. . Greene . Thomas P. . Ohno . Kazumasa . Parmentier . Vivien . Rauscher . Emily . Beatty . Thomas G. . Mukherjee . Sagnick . Wiser . Lindsey S. . Boyer . Martha L. . Rieke . Marcia J. . Stansberry . John A. . 7 Sep 2023 . Methane Throughout the Atmosphere of the Warm Exoplanet WASP-80b . Nature . 623 . 7988 . 709–712 . 10.1038/s41586-023-06687-0 . 37993572 . 2309.04042 . 2023Natur.623..709B. 261660354 .
  89. Xue . Qiao . Bean . Jacob L. . Zhang . Michael . Welbanks . Luis . Lunine . Jonathan . August . Prune . 2024 . JWST Transmission Spectroscopy of HD 209458b: A Supersolar Metallicity, a Very Low C/O, and No Evidence of CH4, HCN, or C2H2 . The Astrophysical Journal Letters . 963 . 1 . L5 . 10.3847/2041-8213/ad2682 . free . 2310.03245 . 2024ApJ...963L...5X .
  90. Constantinou . Savvas . Madhusudhan . Nikku . 2022-08-01 . Characterizing atmospheres of cloudy temperate mini-neptunes with JWST . Monthly Notices of the Royal Astronomical Society . 514 . 2 . 2073–2091 . 10.1093/mnras/stac1277 . free . 0035-8711. 2205.01690 . 2022MNRAS.514.2073C .
  91. Madhusudhan . Nikku . Nixon . Matthew C. . Welbanks . Luis . Piette . Anjali A. A. . Booth . Richard A. . 2020-03-01 . The Interior and Atmosphere of the Habitable-zone Exoplanet K2-18b . The Astrophysical Journal . 891 . 1 . L7 . 10.3847/2041-8213/ab7229 . 2002.11115 . 2020ApJ...891L...7M . 0004-637X. free .
  92. Madhusudhan . Nikku . Sarkar . Subhajit . Constantinou . Savvas . Holmberg . Måns . Piette . Anjali A. A. . Moses . Julianne I. . 2023-10-01 . Carbon-bearing Molecules in a Possible Hycean Atmosphere . The Astrophysical Journal . 956 . 1 . L13 . 10.3847/2041-8213/acf577 . 2309.05566 . 2023ApJ...956L..13M . 0004-637X. free .
  93. Wright . Katherine . 2023-10-13 . The Skinny on Detecting Life with the JWST . Physics . en . 16 . 178. 10.1103/Physics.16.178 . 2023PhyOJ..16..178W . 264332900 . free .
  94. Miles . Brittany E. . Skemer . Andrew J. I. . Morley . Caroline V. . Marley . Mark S. . Fortney . Jonathan J. . Allers . Katelyn N. . Faherty . Jacqueline K. . Geballe . Thomas R. . Visscher . Channon . Schneider . Adam C. . Lupu . Roxana . Freedman . Richard S. . Bjoraker . Gordon L. . 2020-08-01 . Observations of Disequilibrium CO Chemistry in the Coldest Brown Dwarfs . The Astronomical Journal . 160 . 2 . 63 . 10.3847/1538-3881/ab9114 . 2004.10770 . 2020AJ....160...63M . 0004-6256. free .
  95. Book: 1306.2418. 2013cctp.book..277S . 10.2458/azu_uapress_9780816530595-ch12 . 277 . 2013 . Showman . A. P. . Wordsworth . R. D. . Merlis . T. M. . Kaspi . Y. . Comparative Climatology of Terrestrial Planets . Atmospheric Circulation of Terrestrial Exoplanets . 978-0-8165-3059-5 . 52494412 .
  96. https://www.sciencedaily.com/releases/2015/11/151113051338.htm 5400mph winds discovered hurtling around planet outside solar system
  97. 1511.03689 . 10.1088/2041-8205/814/2/L24 . SPATIALLY RESOLVED EASTWARD WINDS AND ROTATION OF HD 189733b . 2015 . Louden . Tom . Wheatley . Peter J. . The Astrophysical Journal . 814 . 2 . L24 . 2015ApJ...814L..24L .
  98. Kreidberg . Laura . Line . Michael R. . Thorngren . Daniel . Morley . Caroline V. . Stevenson . Kevin B. . 2018-05-01 . Water, High-altitude Condensates, and Possible Methane Depletion in the Atmosphere of the Warm Super-Neptune WASP-107b . The Astrophysical Journal . 858 . 1 . L6 . 10.3847/2041-8213/aabfce . 1709.08635 . 2018ApJ...858L...6K . 0004-637X. free .
  99. Grant . David . Lewis . Nikole K. . Wakeford . Hannah R. . Batalha . Natasha E. . Glidden . Ana . Goyal . Jayesh . Mullens . Elijah . MacDonald . Ryan J. . May . Erin M. . Seager . Sara . Stevenson . Kevin B. . Valenti . Jeff A. . Visscher . Channon . Alderson . Lili . Allen . Natalie H. . 2023-10-01 . JWST-TST DREAMS: Quartz Clouds in the Atmosphere of WASP-17b . The Astrophysical Journal . 956 . 2 . L29 . 10.3847/2041-8213/acfc3b . 2310.08637 . 2023ApJ...956L..32G . 0004-637X. free .
  100. Helling . Ch. . Gourbin . P. . Woitke . P. . Parmentier . V. . 2019-06-01 . Sparkling nights and very hot days on WASP-18b: the formation of clouds and the emergence of an ionosphere . Astronomy and Astrophysics . 626 . A133 . 10.1051/0004-6361/201834085 . 1901.08640 . 2019A&A...626A.133H . 0004-6361. free .
  101. Kuzuhara . M. . Tamura . M. . Kudo . T. . Janson . M. . Kandori . R. . Brandt . T. D. . Thalmann . C. . Spiegel . D. . Biller . B. . Carson . J. . Hori . Y. . Suzuki . R. . Burrows . A. . Henning . T. . Turner . E. L. . 2013-09-01 . Direct Imaging of a Cold Jovian Exoplanet in Orbit around the Sun-like Star GJ 504 . The Astrophysical Journal . 774 . 1 . 11 . 10.1088/0004-637X/774/1/11 . 1307.2886 . 2013ApJ...774...11K . 0004-637X. free .
  102. Manjavacas . Elena . Karalidi . Theodora . Vos . Johanna M. . Biller . Beth A. . Lew . Ben W. P. . 2021-11-01 . Revealing the Vertical Cloud Structure of a Young Low-mass Brown Dwarf, an Analog to the β-Pictoris b Directly Imaged Exoplanet, through Keck I/MOSFIRE Spectrophotometric Variability . The Astronomical Journal . 162 . 5 . 179 . 10.3847/1538-3881/ac174c . 2107.12368 . 2021AJ....162..179M . 0004-6256. free .
  103. Aglyamov . Yury S. . Lunine . Jonathan . Becker . Heidi N. . Guillot . Tristan . Gibbard . Seran G. . Atreya . Sushil . Bolton . Scott J. . Levin . Steven . Brown . Shannon T. . Wong . Michael H. . 2021-02-01 . Lightning Generation in Moist Convective Clouds and Constraints on the Water Abundance in Jupiter . Journal of Geophysical Research: Planets . 126 . 2 . e06504 . 10.1029/2020JE006504 . 2101.12361 . 2021JGRE..12606504A . 0148-0227. 2027.42/166445 . 231728590 . free .
  104. Ben-Yami . Maya . Madhusudhan . Nikku . Cabot . Samuel H. C. . Constantinou . Savvas . Piette . Anjali . Gandhi . Siddharth . Welbanks . Luis . 2020-07-01 . Neutral Cr and V in the Atmosphere of Ultra-hot Jupiter WASP-121 b . The Astrophysical Journal . 897 . 1 . L5 . 10.3847/2041-8213/ab94aa . 2006.05995 . 2020ApJ...897L...5B . 0004-637X. free .
  105. Jiang . Zewen . Wang . Wei . Zhao . Gang . Zhai . Meng . Shi . Yaqing . Liu . Yujuan . Zhao . Jingkun . Chen . Yuqin . 2023-06-01 . Detection of Rubidium and Samarium in the Atmosphere of the Ultrahot Jupiter MASCARA-4b . The Astronomical Journal . 165 . 6 . 230 . 10.3847/1538-3881/accb54 . 2304.04948 . 2023AJ....165..230J . 0004-6256. free .
  106. Borsato . N. W. . Hoeijmakers . H. J. . Prinoth . B. . Thorsbro . B. . Forsberg . R. . Kitzmann . D. . Jones . K. . Heng . K. . 2023-05-01 . The Mantis Network. III. Expanding the limits of chemical searches within ultra-hot Jupiters: New detections of Ca I, V I, Ti I, Cr I, Ni I, Sr II, Ba II, and Tb II in KELT-9 b . Astronomy and Astrophysics . 673 . A158 . 10.1051/0004-6361/202245121 . 2304.04285 . 2023A&A...673A.158B . 0004-6361. free .
  107. Web site: New World of Iron Rain . Astrobiology Magazine . 8 January 2003 . https://web.archive.org/web/20130604164408/http://www.astrobio.net/pressrelease/352/new-world-of-iron-rain . 2013-06-04 . usurped.
  108. Howell, Elizabeth (30 August 2013) On Giant Blue Alien Planet, It Rains Molten Glass. SPACE.com
  109. https://www.sciencedaily.com/releases/2009/09/090930165038.htm Raining Pebbles: Rocky Exoplanet Has Bizarre Atmosphere, Simulation Suggests
  110. Morgan, James (14 October 2013) 'Diamond rain' falls on Saturn and Jupiter. BBC.
  111. Sanders, Robert (22 March 2010) Helium rain on Jupiter explains lack of neon in atmosphere. newscenter.berkeley.edu
  112. News: Oxygen Is Not Definitive Evidence of Life on Extrasolar Planets . NAOJ . Astrobiology Web . 10 September 2015 . 2015-09-11 .
  113. 10.1088/2041-8205/785/2/L20. Abiotic Oxygen-Dominated Atmospheres on Terrestrial Habitable Zone Planets. The Astrophysical Journal. 785. 2. L20. 2014. Wordsworth . R. . Pierrehumbert . R. . 1403.2713 . 2014ApJ...785L..20W . 17414970.
  114. 10.1051/0004-6361/201116654. Thermal phase curves of nontransiting terrestrial exoplanets. Astronomy & Astrophysics. 532. A1. 2011. Selsis . F.. Wordsworth . R. D.. Forget . F. . 2011A&A...532A...1S. 1104.4763 . 16696541.
  115. 10.1088/0004-637X/753/2/100. Atmospheric Retrieval for Super-Earths: Uniquely Constraining the Atmospheric Composition with Transmission Spectroscopy. The Astrophysical Journal. 753. 2. 100. 2012. Benneke . B. . Seager . S. . 2012ApJ...753..100B. 1203.4018 . 15328948.
  116. https://www.scientificamerican.com/article/methane-on-mars-titan/ The Mystery of Methane on Mars and Titan
  117. https://www.saraseager.com/research/exoplanet-biosignature-gases/ Exoplanet Biosignature Gases
  118. https://www.universetoday.com/90945/is-there-a-methane-habitable-zone/ Is There a Methane Habitable Zone?
  119. https://www.space.com/13639-alien-life-methane-habitable-zone.html Could Alien Life Exist in the Methane Habitable Zone?
  120. http://www.nss.org/settlement/spaceresources/2004-ExtraterrestrialResources-Bibliography-Abstracts.pdf Recovery and Utilization of Extraterrestrial Resources
  121. https://www.nasa.gov/centers/marshall/news/releases/2015/nasa-tests-methane-powered-engine-components-for-next-generation-landers.html NASA Tests Methane-Powered Engine Components for Next Generation Landers
  122. Web site: Atmosphere of Mercury. April 7, 2013. Cain. Fraser. March 12, 2013. Universe Today. https://web.archive.org/web/20120419015125/http://www.universetoday.com/22088/atmosphere-of-mercury/. April 19, 2012. live.
  123. Donahue. T.M.. Hodges. R.R.. Venus methane and water. Geophysical Research Letters. 20. 1993. 7. 591–594. 10.1029/93GL00513 . 1993GeoRL..20..591D. 2027.42/94590. free.
  124. Stern. S.A.. The Lunar atmosphere: History, status, current problems, and context. Rev. Geophys.. 37. 1999. 4. 453–491. 10.1029/1999RG900005 . 1999RvGeo..37..453S. 10.1.1.21.9994. 10406165.
  125. Web site: Mars Express confirms methane in the Martian atmosphere. European Space Agency. March 17, 2006. https://web.archive.org/web/20060224102528/http://www.esa.int/SPECIALS/Mars_Express/SEMZ0B57ESD_0.html . February 24, 2006 . live.
  126. Web site: Methane-spewing Martians?. Schirber, Michael . January 15, 2009. NASA's Astrobiology Magazine . https://web.archive.org/web/20120409124018/http://www.astrobio.net/exclusive/3004/methane-spewing-martians . 2012-04-09 . usurped.
  127. Web site: Methane on Mars may be result of electrification of dust devils. Atkinson, Nancy . September 11, 2012 . Universe Today.
  128. Web site: Methane on Mars is not an indication of life: UV radiation releases methane from organic materials from meteorites. May 31, 2012. Max-Planck-Gesellschaft.
  129. https://www.washingtonpost.com/wp-dyn/content/article/2009/01/15/AR2009011502222.html Mars Vents Methane in What Could Be Sign of Life
  130. Web site: Making Sense of Mars Methane . October 8, 2008 . Tenenbaum . David . June 9, 2008 . Astrobiology Magazine . https://web.archive.org/web/20080923195833/http://astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=2765&mode=thread&order=0&thold=0 . September 23, 2008 . usurped.
  131. News: Bill . Steigerwald . Martian Methane Reveals the Red Planet is not a Dead Planet. January 15, 2009. NASA. NASA's Goddard Space Flight Center . https://web.archive.org/web/20090117141425/http://www.nasa.gov/mission_pages/mars/news/marsmethane.html. January 17, 2009 . live.
  132. Web site: Mars Curiosity Rover News Telecon -November 2, 2012.
  133. Web site: Kerr . Richard A.. Curiosity Finds Methane on Mars, or Not. November 2, 2012. . November 3, 2012 .
  134. Web site: Webster . Guy . Neal-Jones . Nancy . Brown . Dwayne . NASA Rover Finds Active and Ancient Organic Chemistry on Mars . 16 December 2014 . . 16 December 2014 .
  135. News: Chang . Kenneth . 'A Great Moment': Rover Finds Clue That Mars May Harbor Life . 16 December 2014 . . 16 December 2014 .
  136. Mars methane detection and variability at Gale crater . Science . 23 January 2015 . Webster . Christopher R. . 347 . 6220 . 415–417 . 10.1126/science.1261713 . 2015Sci...347..415W . 25515120. 20304810 .
  137. Web site: Jupiter Fact Sheet . NASA.
  138. Web site: Saturn Fact Sheet . NASA.
  139. 10.1126/science.1121290 . 2006Sci...311.1419W . 16527970 . 311 . 5766 . Cassini ion and neutral mass spectrometer: Enceladus plume composition and structure . March 2006 . 1419–22 . Waite . Jack Hunter Jr. . Science . Combi . M. R. . Ip . W. H. . Cravens . T. E. . McNutt Jr. . R. L. . Kasprzak . W. . Yelle . R. . Luhmann . J. . Niemann . H. . Gell . D. . Magee . B. . Fletcher . G. . Lunine . Jonathan I. . Tseng . W. L. . 3032849 . 6 .
  140. The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens probe . . 438 . 779–784 . 2005 . 10.1038/nature04122. 16319830. Niemann. HB. Atreya. SK. Bauer. SJ. Carignan. GR. Demick. JE. Frost. RL. Gautier. D. Haberman. JA. Harpold. DN. Hunten . D. M. . Israel . G. . Lunine . Jonathan I. . Kasprzak . W. T. . Owen . T. C. . Paulkovich . M. . Raulin . F. . Raaen . E. . Way . S. H. . 7069 . 2005Natur.438..779N. 6 . 2027.42/62703 . 4344046 . free .
  141. Web site: Have We Discovered Evidence For Life On Titan . June 8, 2010 . McKay . Chris . SpaceDaily . June 10, 2010.
  142. Seasonal methane rain discovered on Titan . Wired . Grossman . Lisa . March 17, 2011 .
  143. Web site: Dyches . Preston . Zubritsky . Elizabeth . NASA Finds Methane Ice Cloud in Titan's Stratosphere . October 24, 2014 . . October 31, 2014 .
  144. Web site: Zubritsky . Elizabeth . Dyches . Preston . NASA Identifies Ice Cloud Above Cruising Altitude on Titan . October 24, 2014 . . October 31, 2014 .
  145. Web site: Uranus Fact Sheet . NASA.
  146. Web site: Neptune Fact Sheet . NASA.
  147. Ultraviolet Spectrometer Observations of Neptune and Triton. 1989Sci...246.1459B. December 15, 1989. Science. 246. 1459–1466. 10.1126/science.246.4936.1459. 17756000. 4936. Shemansky. D. F.. Yelle. R. V.. Linick. J. L.. Lunine. J. E.. Dessler. A. J.. Donahue. T. M.. Forrester. W. T.. Hall. D. T.. Herbert. F.. Holberg. J. B.. Hunter. D. M.. Krasnopolsky. V. A.. Linick. S.. Lunine. Jonathan I.. McConnell. J. C.. Moos. H. W.. Sandel. B. R.. Schneider. N. M.. Shemansky. D. E.. Smith. G. R.. Strobel. D. F.. Yelle. R. V.. 21809358. 6.
  148. Book: The Grand Tour: A Traveler's Guide to the Solar System. Miller, Ron. Ron Miller (artist and author). Hartmann, William K.. 2005. 172–73. Workman Publishing. Thailand. 3rd. 978-0-7611-3547-0.
  149. 6 . 10.1126/science.261.5122.745 . 17757212 . Surface Ices and the Atmospheric Composition of Pluto. Science. 261. 5122. 745–748 . 1993. Owen . T. C. . Roush . T. L. . Cruikshank . D. P. . Elliot . J. L. . Young . L. A. . De Bergh . C. . Schmitt . B. . Geballe . T. R. . Brown . R. H. . Bartholomew . M. J.. 1993Sci...261..745O . 6039266 .
  150. Web site: Pluto . SolStation . 2006 . March 28, 2007.
  151. Charon's size and an upper limit on its atmosphere from a stellar occultation. Nature . 2006 . 439 . 52–4 . 10.1038/nature04351 . 16397493 . Sicardy . B . Bellucci . A . Gendron . E . Lacombe . F . Lacour . S . Lecacheux . J . Lellouch . E . Renner . S . Pau . S . Roques . F. . Widemann . T. . Colas . F. . Vachier . F. . Martins . R. Vieira . Ageorges . N. . Hainaut . O. . Marco . O. . Beisker . W. . Hummel . E. . Feinstein . C. . Levato . H. . Maury . A. . Frappa . E. . Gaillard . B. . Lavayssière . M. . Di Sora . M. . Mallia . F. . Masi . G. . Behrend . R. . Carrier . F. . 7072 . 2006Natur.439...52S. 4411478 . 6 . 11336/39754 . free .
  152. Web site: Gemini Observatory Shows That "10th Planet" Has a Pluto-Like Surface. Gemini Observatory. 2005. May 3, 2007.
  153. Mumma . M.J. . Disanti . M.A. . Dello Russo . N. . Fomenkova . M. . Magee-Sauer . K. . Kaminski . C.D. . Xie . D.X. . Detection of Abundant Ethane and Methane, Along with Carbon Monoxide and Water, in Comet C/1996 B2 Hyakutake: Evidence for Interstellar Origin . Science . 1996 . 272 . 1310–1314 . 1996Sci...272.1310M . 10.1126/science.272.5266.1310 . 8650540 . 5266. 27362518 .
  154. Web site: Organic molecules found on alien world for first time. Battersby, Stephen . February 11, 2008.
  155. Web site: Meteors might add methane to exoplanet atmospheres. Choi, Charles M.. September 17, 2012. NASA's Astrobiology Magazine. March 25, 2018. https://web.archive.org/web/20130602073250/http://www.astrobio.net/exclusive/5021/meteors-might-add-to-exoplanet-atmosphere. June 2, 2013. usurped.
  156. 10.1086/170304. 1991ApJ...376..556L. Discovery of interstellar methane – Observations of gaseous and solid CH4 absorption toward young stars in molecular clouds. The Astrophysical Journal. 376. 556. 1991. Lacy . J. H.. Carr . J. S.. Evans . N. J., I. . Baas . F.. Achtermann . J. M.. Arens . J. F..

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