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61-610: Palaeoproterozoic mobile belts surround the continental blocks and cratonic fragments of the NAC. Throughout the Mesoproterozoic , Neoproterozoic , and Mesozoic (1350–550  Ma ), when these blocks still formed a coherent craton, repeated continental extension resulted in lithospheric thinning. The NAC finally broke up at c. 60 Ma with the opening of the Labrador Sea . Ultramafic magmatism has occurred continuously in

122-462: A full moon on Earth. Saturn's rings are hidden from view owing to the alignment of Titan's orbital plane and the plane of the rings. Saturn is expected to show phases, akin to the phases of Venus on Earth, that partially illuminate the surface of Titan at night, except for eclipses . From outer space , Cassini images from near-infrared to UV wavelengths have shown that the twilight periods ( phase angles > 150°) are brighter than

183-640: A mantle plume . A rift system that developed during the Mesozoic began to fraction the NAC, and the initial stages of the break-up of the NAC produced the kimberlite and carbonatite deposits along the Labrador Sea. In Greenland the NAC is primarily made of tonalite–trondhjemite–granodiorite orthogneisses separated and obscured by supracrustal belts, anorthosite complexes, and granite intrusions. A series of terranes have been distinguished in Greenland: north of

244-433: A big Hadley circulation that is occurring from pole to pole. Similar to the hydrological cycle on Earth, Titan features a methane cycle. This methane cycle results in surface formations that resemble formations we find on Earth. Lakes of methane and ethane are found across Titan's polar regions. Methane condenses into clouds in the atmosphere, and then precipitates onto the surface. This liquid methane then flows into

305-478: A dense atmosphere on Titan has been enigmatic as the atmospheres of the structurally similar satellites of Jupiter , Ganymede and Callisto , are negligible. Although the disparity is still poorly understood, data from recent missions have provided basic constraints on the evolution of Titan's atmosphere. Roughly speaking, at the distance of Saturn , solar insolation and solar wind flux are sufficiently low that elements and compounds that are volatile on

366-451: A key role in the formation of more complex molecules, which are thought to be tholins , and may form the basis for polycyclic aromatic hydrocarbons , cyanopolyynes and their derivatives. Remarkably, negative ions such as these have previously been shown to enhance the production of larger organic molecules in molecular clouds beyond our Solar System, a similarity which highlights the possible wider relevance of Titan's negative ions. There

427-471: A more extended atmosphere, with scale heights of 15–50 km (9–31 mi) in comparison to 5–8 km (3.1-5 mi) on Earth. Voyager data, combined with data from Huygens and radiative-convective models provide increased understanding of Titan's atmospheric structure. Titan's atmospheric chemistry is diverse and complex. Each layer of the atmosphere has unique chemical interactions occurring within that are then interacting with other sub layers in

488-455: A non-negligible role. The interaction between Titan’s atmosphere and Saturn’s magnetic environment underscores the complex interplay between celestial bodies and their atmospheres, revealing a dynamic system shaped by both internal chemical processes and external astronomical conditions; future studies, if approached, may help to prove (or disprove) the impact of a changing magnetosphere on a dense atmosphere like that of Titan. The persistence of

549-515: A short time compared to the age of the Solar System. This suggests that methane must be somehow replenished by a reservoir on or within Titan itself. Most of the methane on Titan is in the atmosphere. Methane is transported through the cold trap at the tropopause. Therefore the circulation of methane in the atmosphere influences the radiation balance and chemistry of other layers in the atmosphere. If there

610-413: A typical sunny day may look like standing on the surface of Titan based on radiative transfer models. For astronauts who see with visible light , the daytime sky has a distinctly dark orange color and appears uniform in all directions due to significant Mie scattering from the many high-altitude haze layers. The daytime sky is calculated to be ~100–1000 times dimmer than an afternoon on Earth, which

671-648: A wealth of information about Titan, and the Saturn system in general, since entering orbit on July 1, 2004. It was determined that Titan's atmospheric isotopic abundances were evidence that the abundant nitrogen in the atmosphere came from materials in the Oort cloud , associated with comets , and not from the materials that formed Saturn in earlier times. It was determined that complex organic chemicals could arise on Titan, including polycyclic aromatic hydrocarbons , propylene , and methane . The Dragonfly mission by NASA

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732-417: Is methane clathrates . Clathrates are compounds in which an ice lattice surrounds a gas particle, much like a cage. In this case, methane gas is surrounded by a water crystal cage. These methane clathrates could be present underneath Titan's icy surface, having formed much earlier in Titan's history. Through the dissociation of methane clathrates, methane could be outgassed into the atmosphere, replenishing

793-604: Is a stub . You can help Misplaced Pages by expanding it . Paleoproterozoic Gradstein et al., 2012 Jatulian/Eukaryian Period, 2250–2060 Ma Gradstein et al., 2012 Columbian Period, 2060–1780 Ma The Paleoproterozoic Era (also spelled Palaeoproterozoic ) is the first of the three sub-divisions ( eras ) of the Proterozoic eon , and also the longest era of the Earth's geological history , spanning from 2,500 to 1,600 million years ago (2.5–1.6  Ga ). It

854-413: Is a pattern of air circulation found flowing in the direction of Titan's rotation, from west to east. In addition, seasonal variation in the atmospheric circulation has also been detected. Observations by Cassini of the atmosphere made in 2004 also suggest that Titan is a "super rotator", like Venus , with an atmosphere that rotates much faster than its surface. The atmospheric circulation is explained by

915-416: Is a reservoir of methane on Titan, the cycle would only be stable over geologic timescales. Evidence that Titan's atmosphere contains over a thousand times more methane than carbon monoxide would appear to rule out significant contributions from cometary impacts, because comets are composed of more carbon monoxide than methane. That Titan might have accreted an atmosphere from the early Saturnian nebula at

976-472: Is about 1.19 times as massive as Earth's overall, or about 7.3 times more massive on a per surface area basis. It supports opaque haze layers that block most visible light from the Sun and other sources and renders Titan's surface features obscure. The atmosphere is so thick and the gravity so low that humans could fly through it by flapping "wings" attached to their arms. Titan's lower gravity means that its atmosphere

1037-518: Is about 50% higher than on Earth at 1.5 bars (147 kPa) which is near the triple point of methane and allows there to be gaseous methane in the atmosphere and liquid methane on the surface. The orange color as seen from space is produced by other more complex chemicals in small quantities, possibly tholins , tar-like organic precipitates. The presence of a significant atmosphere was first suspected by Spanish astronomer Josep Comas i Solà , who observed distinct limb darkening on Titan in 1903 from

1098-524: Is far more extended than Earth's; even at a distance of 975 km, the Cassini spacecraft had to make adjustments to maintain a stable trajectory against atmospheric drag. The atmosphere of Titan is opaque at many wavelengths and a complete reflectance spectrum of the surface is impossible to acquire from the outside. It was not until the arrival of Cassini–Huygens in 2004 that the first direct images of Titan's surface were obtained. The Huygens probe

1159-664: Is further subdivided into four geologic periods , namely the Siderian , Rhyacian , Orosirian and Statherian . Paleontological evidence suggests that the Earth's rotational rate ~1.8 billion years ago equated to 20-hour days, implying a total of ~450 days per year. It was during this era that the continents first stabilized. The Earth's atmosphere was originally a weakly reducing atmosphere consisting largely of nitrogen , methane , ammonia , carbon dioxide and inert gases , in total comparable to Titan's atmosphere . When oxygenic photosynthesis evolved in cyanobacteria during

1220-479: Is increased over the blackbody temperature by a strong greenhouse effect caused by infrared absorption by pressure-induced opacity of Titan's atmosphere, but the greenhouse warming is somewhat reduced by an effect tagged by Pollack the anti-greenhouse effect , absorbing some incoming solar energy before it can reach the surface, leading to cooler surface temperatures than if methane were less abundant. The greenhouse effect increases surface temperature by 21 K, while

1281-615: Is interpreted as having resulted from increased biomass and carbon burial during and after the Great Oxidation Event: Subducted carbonaceous sediments are hypothesized to have lubricated compressive deformation and led to crustal thickening. Felsic volcanism in what is now northern Sweden led to the formation of the Kiruna and Arvidsjaur porphyries . The lithospheric mantle of Patagonia's oldest blocks formed. Titan%27s atmosphere The atmosphere of Titan

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1342-408: Is largely due to the differing impacts of greenhouse and anti-greenhouse effects in Earth's and Titan's atmospheres, respectively. Titan orbits within Saturn's magnetosphere for approximately 95% of its orbital period. During this time, charged particles trapped in the magnetosphere interact with Titan's upper atmosphere as the moon passes by, leading to the generation of a denser haze. Consequently,

1403-561: Is planning to land a large aerial vehicle on Titan in 2034. The mission will study Titan's habitability and prebiotic chemistry at various locations. The drone-like aircraft will perform measurements of geologic processes, and surface and atmospheric composition. Observations from the Voyager space probes have shown that the Titanean atmosphere is denser than Earth 's, with a surface pressure about 1.48 times that of Earth's. Titan's atmosphere

1464-457: Is similar to the viewing conditions of a thick smog or dense fire smoke . The sunsets on Titan are expected to be "underwhelming events", where the Sun disappears about half-way up in the sky (~50° above the horizon ) with no distinct change in color. After that, the sky will slowly darken until it reaches night. However, the surface is expected to remain as bright as the full Moon up to 1 Earth day after sunset . In near-infrared light ,

1525-977: Is the dense layer of gases surrounding Titan , the largest moon of Saturn . Titan is the only natural satellite of a planet in the Solar System with an atmosphere that is denser than the atmosphere of Earth and is one of two moons with an atmosphere significant enough to drive weather (the other being the atmosphere of Triton ). Titan's lower atmosphere is primarily composed of nitrogen (94.2%), methane (5.65%), and hydrogen (0.099%). There are trace amounts of other hydrocarbons, such as ethane , diacetylene , methylacetylene , acetylene , propane , PAHs and of other gases, such as cyanoacetylene , hydrogen cyanide , carbon dioxide , carbon monoxide , cyanogen , acetonitrile , argon and helium . The isotopic study of nitrogen isotopes ratio also suggests acetonitrile may be present in quantities exceeding hydrogen cyanide and cyanoacetylene . The surface pressure

1586-441: Is widely considered one of the first and most significant mass extinctions on Earth. The organisms that thrived after the extinction were mainly aerobes that evolved bioactive antioxidants and eventually aerobic respiration , and surviving anaerobes were forced to live symbiotically alongside aerobes in hybrid colonies, which enabled the evolution of mitochondria in eukaryotic organisms . The Palaeoproterozoic represents

1647-562: The Fabra Observatory in Barcelona , Catalonia . This observation was confirmed by Dutch astronomer Gerard P. Kuiper in 1944 using a spectroscopic technique that yielded an estimate of an atmospheric partial pressure of methane of the order of 100 millibars (10 kPa). Subsequent observations in the 1970s showed that Kuiper's figures had been significant underestimates; methane abundances in Titan's atmosphere were ten times higher, and

1708-500: The Great Oxidation Event , which brought atmospheric oxygen from near none to up to 10% of the modern level. At the beginning of the preceding Archean eon, almost all existing lifeforms were single-cell prokaryotic anaerobic organisms whose metabolism was based on a form of cellular respiration that did not require oxygen, and autotrophs were either chemosynthetic or relied upon anoxygenic photosynthesis . After

1769-506: The Mesoarchean , the increasing amount of byproduct dioxygen began to deplete the reductants in the ocean , land surface and the atmosphere. Eventually all surface reductants (particularly ferrous iron , sulfur and atmospheric methane ) were exhausted, and the atmospheric free oxygen levels soared permanently during the Siderian and Rhyacian periods in an aerochemical event called

1830-466: The N– N isotopic ratio , because the lighter N is preferentially lost from the upper atmosphere under photolysis and heating. Because Titan's original N– N ratio is poorly constrained, the early atmosphere may have had more N 2 by factors ranging from 1.5 to 100 with certainty only in the lower factor. Because N 2 is the primary component (98%) of Titan's atmosphere, the isotopic ratio suggests that much of

1891-516: The terrestrial planets tend to accumulate in all three phases . Titan's surface temperature is also quite low, about 94 K (–179 C/–290 F). Consequently, the mass fractions of substances that can become atmospheric constituents are much larger on Titan than on Earth . In fact, current interpretations suggest that only about 50% of Titan's mass is silicates , with the rest consisting primarily of various H 2 O ( water ) ices and NH 3 ·H 2 O ( ammonia hydrates ). NH 3 , which may be

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1952-528: The 1.9–1.8 Ga Akitkan Orogen in Siberia; the ~1.95 Ga Khondalite Belt; the ~1.85 Ga Trans-North China Orogen in North China; and the 1.8-1.6 Ga Yavapai and Mazatzal orogenies in southern North America. That pattern of collision belts supports the formation of a Proterozoic supercontinent named Columbia or Nuna . That continental collisions suddenly led to mountain building at large scale

2013-666: The 2.1–2.0 Ga Trans-Amazonian and Eburnean orogens in South America and West Africa; the ~2.0 Ga Limpopo Belt in southern Africa; the 1.9–1.8 Ga Trans-Hudson , Penokean , Taltson–Thelon, Wopmay , Ungava and Torngat orogens in North America, the 1.9–1.8 Ga Nagssugtoqidian Orogen in Greenland; the 1.9–1.8 Ga Kola–Karelia, Svecofennian , Volhyn-Central Russian, and Pachelma orogens in Baltica (Eastern Europe);

2074-593: The Frederikshåb Isblink Glacier. The Akia , Isukasia, and Kapisilik terranes probably collided c.  2950 Ma in the Isukasia orogeny, although events are masked by Neoarchaean overprinting . The Færingehavn, Tre Brødre, and Tasiusarsuaq terranes merged c.  2800–2700 Ma in the Tasiusarsuaq orogeny, although these terranes were affected by Neoarchaean folding and deformation. In

2135-522: The Great Oxygenation Event, the then mainly archaea -dominated anaerobic microbial mats were devastated as free oxygen is highly reactive and biologically toxic to cellular structures. This was compounded by a 300- million-year -long global icehouse event known as the Huronian glaciation — at least partly due to the depletion of atmospheric methane, a powerful greenhouse gas — resulted in what

2196-692: The Kapisilik orogeny c.  2650–2580 Ma terranes around the Godthåbsfjord, mostly north of Nuuk, were accreted along the Iivinnguit fault. South of Frederikshåb Isblink the Paamiut and Neria blocks probably collided c.  2850–2830 Ma in the Paamiut orogeny. They in turn collided with the Sioraq block and Tasiusarsuaq terranes 2760–270 Ma in the Tasiusarsuaq orogeny. This geology article

2257-578: The NAC for almost 3 billion years, but kimberlite -producing magmatism has only occurred in two stages: in the Neoproterozoic ( c.  600–550 Ma ) in the northern NAC and in the Jurassic ( c.  200–150 Ma ) in the southern NAC. Magmatism during the Neoproterozoic was caused by either the opening of the Iapetus Ocean , lithospheric thinning along a fracture zone, or the appearance of

2318-593: The Saturnian sub- nebula . Instead, the temperature may have been higher than 75 K, limiting even the accumulation of NH 3 as hydrates . Temperatures would have been even higher in the Jovian sub-nebula due to the greater gravitational potential energy release, mass, and proximity to the Sun, greatly reducing the NH 3 inventory accreted by Callisto and Ganymede. The resulting N 2 atmospheres may have been too thin to survive

2379-427: The Sun is expected to disappear fairly close to the horizon. Titan's atmospheric optical depth is the lowest at 5 microns . So, the Sun at 5 microns may even be visible when it is below the horizon due to atmospheric refraction . Similar to images of Martian sunsets from Mars rovers , a fan-like corona is seen to develop above the Sun due to scattering from haze or dust at high-altitudes. In regards to Saturn ,

2440-402: The anti-greenhouse takes away half this effect, reducing this to an increase of 12 K. When comparing the atmospheric temperature profiles of Earth and Titan, stark contrasts emerge. On Earth, the temperature typically increases as altitude decreases from 80 to 60 kilometers above the surface. In contrast, Titan’s temperature profile shows a decline over the same altitude range. This variation

2501-517: The atmosphere ( hydrodynamic escape ). Such an event could be driven by heating and photolysis effects of the early Sun's higher output of X-ray and ultraviolet (XUV) photons. Because Callisto and Ganymede are structurally similar to Titan, it is unclear why their atmospheres are insignificant relative to Titan's. Nevertheless, the origin of Titan's N 2 via geologically ancient photolysis of accreted and degassed NH 3 , as opposed to degassing of N 2 from accretionary clathrates , may be

North Atlantic Craton - Misplaced Pages Continue

2562-505: The atmosphere from the solar wind . In November 2007, scientists uncovered evidence of negative ions with roughly 13 800 times the mass of hydrogen in Titan's ionosphere, which are thought to fall into the lower regions to form the orange haze which obscures Titan's surface. The smaller negative ions have been identified as linear carbon chain anions with larger molecules displaying evidence of more complex structures, possibly derived from benzene . These negative ions appear to play

2623-399: The atmosphere has been lost over geologic time . Nevertheless, atmospheric pressure on its surface remains nearly 1.5 times that of Earth as it began with a proportionally greater volatile budget than Earth or Mars . It is possible that most of the atmospheric loss was within 50 million years of accretion , from a highly energetic escape of light atoms carrying away a large portion of

2684-524: The atmosphere. For instance, 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. The table below highlights the production and loss mechanisms of the most abundant photochemically produced molecules in Titan's atmosphere. Titan's internal magnetic field is negligible, and perhaps even nonexistent, although studies in 2008 showed that Titan retains remnants of Saturn's magnetic field on

2745-465: The atmospheric erosion effects that Titan has withstood. An alternative explanation is that cometary impacts release more energy on Callisto and Ganymede than they do at Titan due to the higher gravitational field of Jupiter . That could erode the atmospheres of Callisto and Ganymede, whereas the cometary material would actually build Titan's atmosphere. However, the H– H (i.e. D–H) ratio of Titan's atmosphere

2806-407: The brief occasions when it passes outside Saturn's magnetosphere and is directly exposed to the solar wind . This may ionize and carry away some molecules from the top of the atmosphere. One interesting case was detected as an example of the coronal mass ejection impact onto Saturn's magnetosphere, causing Titan's orbit to be exposed to the shocked solar wind in the magnetosheath. This leads to

2867-399: The daytime on Titan. This observation has not been observed on any other planetary body with a thick atmosphere. The Titanean twilight outshining the dayside is due to a combination of Titan's atmosphere extending hundreds of kilometers above the surface and intense forward Mie scattering from the haze. Radiative transfer models have not reproduced this effect. The temperature of Titan

2928-613: The era from which the oldest cyanobacterial fossils, those of Eoentophysalis belcherensis from the Kasegalik Formation in the Belcher Islands of Nunavut , are known. By 1.75 Ga, thylakoid-bearing cyanobacteria had evolved, as evidenced by fossils from the McDermott Formation of Australia. Many crown node eukaryotes (from which the modern-day eukaryotic lineages would have arisen) have been approximately dated to around

2989-572: The increased particle precipitation and the formation of extreme electron densities in Titan's ionosphere. Its orbital distance of 20.3 Saturn radii does place it within Saturn's magnetosphere occasionally. However, the difference between Saturn's rotational period (10.7 hours) and Titan's orbital period (15.95 days) causes a relative speed of about 100 km/s between the Saturn's magnetized plasma and Titan. That can actually intensify reactions causing atmospheric loss, instead of guarding

3050-402: The key to a correct inference. Had N 2 been released from clathrates, Ar and Ar that are inert primordial isotopes of the Solar System should also be present in the atmosphere, but neither has been detected in significant quantities. The insignificant concentration of Ar and Ar also indicates that the ~40 K temperature required to trap them and N 2 in clathrates did not exist in

3111-403: The lakes. Some of the methane in the lakes will evaporate over time, and form clouds in the atmosphere again, starting the process over. However, since methane is lost in the thermosphere, there has to be a source of methane to replenish atmospheric methane. Energy from the Sun should have converted all traces of methane in Titan's atmosphere into more complex hydrocarbons within 50 million years —

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3172-435: The original source of Titan's atmospheric N 2 ( dinitrogen ), may constitute as much as 8% of the NH 3 ·H 2 O mass. Titan is most likely differentiated into layers, where the liquid water layer beneath ice I h may be rich in NH 3 . Tentative constraints are available, with the current loss mostly due to low gravity and solar wind aided by photolysis . The loss of Titan's early atmosphere can be estimated with

3233-422: The planet is nearly fixed in its position in the sky because Titan's orbit is tidally locked around Saturn. However, there is a small 3° east-to-west motion over a Titan year due to the orbital eccentricity , similar to the analemma on Earth. Sunlight reflected off of Saturn, Saturnshine, is about 1000 times weaker than solar insolation on the surface of Titan. Even though Saturn appears several times bigger in

3294-522: The sky than the Moon in Earth's sky, the outline of Saturn is masked out by the brighter Sun during the daytime. Saturn may become discernible at night, but only at a wavelength of 5 microns. This is due to two factors: the small optical depth of Titan's atmosphere at 5 microns and the strong 5 μm emissions from Saturn's night side. In visible light, Saturn will make the sky on Titan's Saturn-facing side appear slightly brighter, similar to an overcast night with

3355-407: The sunsets resemble a Martian sunset or dusty desert sunset. Mie scattering has a weaker influence at longer infrared wavelengths, allowing for more colorful and variable sky conditions. During the daytime, the Sun has a noticeable solar corona that transitions color from white to "red" over the afternoon. The afternoon sky brightness is ~100 times dimmer than Earth. As evening time approaches,

3416-471: The supply. On December 1, 2022, astronomers reported viewing clouds, likely made of methane , moving across Titan, using the James Webb Space Telescope . Sky brightness and viewing conditions are expected to be quite different from Earth and Mars due to Titan's farther distance from the Sun (~10  AU ) and complex haze layers in its atmosphere. The sky brightness model videos show what

3477-416: The surface pressure was at least double what he had predicted. The high surface pressure meant that methane could only form a small fraction of Titan's atmosphere. In 1980, Voyager 1 made the first detailed observations of Titan's atmosphere, revealing that its surface pressure was higher than Earth's, at 1.5 bars (about 1.48 times that of Earth's). The joint NASA/ESA Cassini-Huygens mission provided

3538-407: The time of formation also seems unlikely; in such a case, it ought to have atmospheric abundances similar to the solar nebula, including hydrogen and neon . Many astronomers have suggested that the ultimate origin for the methane in Titan's atmosphere is from within Titan itself, released via eruptions from cryovolcanoes . Another possible source for methane replenishment in Titan's atmosphere

3599-672: The time of the Paleoproterozoic Era. While there is some debate as to the exact time at which eukaryotes evolved, current understanding places it somewhere in this era. Statherian fossils from the Changcheng Group in North China provide evidence that eukaryotic life was already diverse by the late Palaeoproterozoic. During this era, the earliest global-scale continent-continent collision belts developed. The associated continent and mountain building events are represented by

3660-408: The variability of Saturn’s magnetic field over its approximately 30-year orbital period could cause variations in these interactions, potentially increasing or decreasing the haze density. Although most observed variations in Titan's atmosphere during its orbital period are typically attributed to its direct interactions with sunlight, the influence of Saturn's magnetospheric changes is believed to play

3721-451: Was unable to detect the direction of the Sun during its descent, and although it was able to take images from the surface, the Huygens team likened the process to "taking pictures of an asphalt parking lot at dusk". Titan's vertical atmospheric structure is similar to Earth. They both have a troposphere, stratosphere, mesosphere, and thermosphere. However, Titan's lower surface gravity creates

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