What Is Mars Atmosphere Made Of - Universe Today Universe Today What Is Mars Atmosphere Made Of Article Updated: 24 Dec , 2015 by Jerry Coffey [/caption]I think that one of the most interesting questions that have been posed of late is ‘what is Mar’s atmosphere made of?’ There has been a great deal of study done on this topic and interest is increasing since the discovery of methane, a possible indicator of life. The atmosphere of Mars is over 95% carbon dioxide, 95.32% to be exact. The breakdown of gases goes like this: Carbon dioxide 95.32% Nitric oxide .0013% Trace gases(including krypton, methane, etc) The Martian atmosphere has four main layers: lower, middle, upper, and exosphere. The lower atmosphere is a warm region(around 210 K). It is warmed by airborne dust(1.5 micrometers across) and heat radiated from the surface. This airborne dust gives the planet its ruddy brown appearance. The middle atmosphere is features a jetstream similar to Earth’s. The upper atmosphere is heated by the solar wind and the temperatures are much higher than at the surface.

This heat separates the gases. The exosphere starts at about 200 km and has no clear end. It just tapers off into space. The carbon dioxide in the atmosphere freezes for part of the year and may drop to the surface. As much as 25% of the atmospheric carbon dioxide condenses at the polar caps into solid ice(dry ice) because the Martian poles are not exposed to sunlight during the planet’s winter. When the poles are again exposed to sunlight, the ice returns to its gas form and rises back into the atmosphere. So, a significant annual variation in the atmospheric pressure and atmospheric composition around the Martian poles. The methane mentioned earlier is used to show the possibility of life on Mars. While it is a byproduct of life, it is also a result of volcanism, geothermal process, and hydrothermal activity. Methane is an unstable gas, so there has to be a source on the planet that is constantly replenishing it. It has to be a very active source, because studies have shown that the methane is destroyed in less than on Earth year. It is thought that peroxides and perchlorates in the soil or that it condenses and evaporates seasonally from clathrates.

Now you answer ‘ what is Mar’s atmosphere made of?’ the next time it comes up. You can be sure that the methane component will continue to be studied by rovers, orbiters, and, in the future, astronauts. We have written many articles about the atmosphere of Mars for Universe Today. Here’s an article about the air on Mars , and here’s an article about Mars’ comparison with Earth . If you’d like more info on Mars, check out Hubblesite’s News Releases about Mars , and here’s a link to the NASA Mars Exploration home page . We’ve also recorded an episode of Astronomy Cast all about Mars. Listen here, Episode 52: Mars . Reference: NASA - Martian Methane Reveals the Red Planet is not a Dead Planet Martian Methane Reveals the Red Planet is not a Dead Planet 01.15.09 > View streaming video > Larger, labeled image Mars today is a world of cold and lonely deserts, apparently without life of any kind, at least on the surface.

Worse still, it looks like Mars has been cold and dry for billions of years, with an atmosphere so thin, any liquid water on the surface quickly boils away while the sun's ultraviolet radiation scorches the ground. But there is evidence of a warmer and wetter past -- features resembling dry riverbeds and minerals that form in the presence of water indicate water once flowed through Martian sands. Since liquid water is required for all known forms of life, scientists wonder if life could have risen on Mars, and if it did, what became of it as the Martian climate changed. New research reveals there is hope for Mars yet. The first definitive detection of methane in the atmosphere of Mars indicates the planet is still alive, in either a biologic or geologic sense, according to a team of NASA and university scientists. "Methane is quickly destroyed in the Martian atmosphere in a variety of ways, so our discovery of substantial plumes of methane in the northern hemisphere of Mars in 2003 indicates some ongoing process is releasing the gas," said Dr. Michael Mumma of NASA's Goddard Space Flight Center in Greenbelt, Md.

"At northern mid-summer, methane is released at a rate comparable to that of the massive hydrocarbon seep at Coal Oil Point in Santa Barbara, Calif." Scientists don't yet know enough to say with certainty what the source of the Martian methane is, but this artist's concept depicts a possibility. In this illustration, subsurface water, carbon dioxide and the planet's internal heat combine to release methane. Although we don’t have evidence on Mars of active volcanoes today, ancient methane trapped in ice "cages" might now be released. Credit: NASA/Susan Twardy > Larger image Methane -- four atoms of hydrogen bound to a carbon atom -- is the main component of natural gas on Earth. It's of interest to astrobiologists because organisms release much of Earth's methane as they digest nutrients. However, other purely geological processes, like oxidation of iron, also release methane. "Right now, we don’t have enough information to tell if biology or geology -- or both -- is producing the methane on Mars," said Mumma. "But it does tell us that the planet is still alive, at least in a geologic sense.

It's as if Mars is challenging us, saying, hey, find out what this means." Mumma is lead author of a paper on this research appearing in Science Express Jan. 15. If microscopic Martian life is producing the methane, it likely resides far below the surface, where it's still warm enough for liquid water to exist. Liquid water, as well as energy sources and a supply of carbon, are necessary for all known forms of life. "On Earth, microorganisms thrive 2 to 3 kilometers (about 1.2 to 1.9 miles) beneath the Witwatersrand basin of South Africa, where natural radioactivity splits water molecules into molecular hydrogen (H2) and oxygen. The organisms use the hydrogen for energy. It might be possible for similar organisms to survive for billions of years below the permafrost layer on Mars, where water is liquid, radiation supplies energy, and carbon dioxide provides carbon," said Mumma. "Gases, like methane, accumulated in such underground zones might be released into the atmosphere if pores or fissures open during the warm seasons, connecting the deep zones to the atmosphere at crater walls or canyons," said Mumma.

"Microbes that produced methane from hydrogen and carbon dioxide were one of the earliest forms of life on Earth," noted Dr. Carl Pilcher, Director of the NASA Astrobiology Institute which partially supported the research. "If life ever existed on Mars, it's reasonable to think that its metabolism might have involved making methane from Martian atmospheric carbon dioxide." However, it is possible a geologic process produced the Martian methane, either now or eons ago. On Earth, the conversion of iron oxide (rust) into the serpentine group of minerals creates methane, and on Mars this process could proceed using water, carbon dioxide, and the planet's internal heat. Although we don’t have evidence on Mars of active volcanoes today, ancient methane trapped in ice "cages" called clathrates might now be released. The team found methane in the atmosphere of Mars by carefully observing the planet over several Mars years (and all Martian seasons) with NASA's Infrared Telescope Facility, run by the University of Hawaii, and the W. M. Keck telescope, both at Mauna Kea, Hawaii. The team used spectrometer instruments attached to the telescopes to make the detection.

Spectrometers spread light into its component colors, like a prism separates white light into a rainbow. The team looked for dark areas in specific places along the rainbow (light spectrum) where methane was absorbing sunlight reflected from the Martian surface. They found three such areas, called absorption lines, which together are a definitive signature of methane, according to the team. They were able to distinguish lines from Martian methane from the methane in Earth's atmosphere because the motion of the Red Planet shifted the position of the Martian lines, much as a speeding ambulance causes its siren to change pitch as it passes by. "We observed and mapped multiple plumes of methane on Mars, one of which released about 19,000 metric tons of methane," said Dr. Geronimo Villanueva of the Catholic University of America, Washington, D.C. Villanueva is stationed at NASA Goddard and is co-author of the paper. "The plumes were emitted during the warmer seasons -- spring and summer -- perhaps because the permafrost blocking cracks and fissures vaporized, allowing methane to seep into the Martian air. Curiously, some plumes had water vapor while others did not," said Villanueva.

According to the team, the plumes were seen over areas that show evidence of ancient ground ice or flowing water. For example, plumes appeared over northern hemisphere regions such as east of Arabia Terra, the Nili Fossae region, and the south-east quadrant of Syrtis Major, an ancient volcano 1,200 kilometers (about 745 miles) across. It will take future missions, like NASA's Mars Science Laboratory, to discover the origin of the Martian methane. One way to tell if life is the source of the gas is by measuring isotope ratios. Isotopes are heavier versions of an element; for example, deuterium is a heavier version of hydrogen. In molecules that contain hydrogen, like water and methane, the rare deuterium occasionally replaces a hydrogen atom. Since life prefers to use the lighter isotopes, if the methane has less deuterium than the water released with it on Mars, it's a sign that life is producing the methane. The research was funded by NASA's Planetary Astronomy Program and the NASA Astrobiology Institute. Related links: What Is The Atmosphere Like On Other Planets? - Universe Today Universe Today What Is The Atmosphere Like On Other Planets?

Article Updated: 5 Jul , 2016 by Matt Williams Here on Earth, we tend to take our atmosphere for granted, and not without reason. Our atmosphere has a lovely mix of nitrogen and oxygen (78% and 21% respectively) with trace amounts of water vapor, carbon dioxide and other gaseous molecules. What’s more, we enjoy an atmospheric pressure of 101.325 kPa, which extends to an altitude of about 8.5 km. In short, our atmosphere is plentiful and life-sustaining. But what about the other planets of the Solar System? How do they stack up in terms of atmospheric composition and pressure? We know for a fact that they are not breathable by humans and cannot support life. But just what is the difference between these balls of rock and gas and our own? For starters, it should be noted that every planet in the Solar System has an atmosphere of one kind or another. And these range from incredibly thin and tenuous (such as Mercury’s “exosphere”) to the incredibly dense and powerful – which is the case for all of the gas giants.

And depending on the composition of the planet, whether it is a terrestrial or a gas/ice giant, the gases that make up its atmosphere range from either the hydrogen and helium to more complex elements like oxygen, carbon dioxide, ammonia and methane. Mercury’s Atmosphere: Mercury is too hot and too small to retain an atmosphere. However, it does have a tenuous and variable exosphere that is made up of hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a combined pressure level of about 10-14 bar (one-quadrillionth of Earth’s atmospheric pressure). It is believed this exosphere was formed from particles captured from the Sun, volcanic outgassing and debris kicked into orbit by micrometeorite impacts. A High-resolution Look over Mercury’s Northern Horizon. Credit: NASA/MESSENGER Because it lacks a viable atmosphere, Mercury has no way to retain the heat from the Sun. As a result of this and its high eccentricity, the planet experiences considerable variations in temperature.

Whereas the side that faces the Sun can reach temperatures of up to 700 K (427° C), while the side in shadow dips down to 100 K (-173° C). Venus’ Atmosphere: Surface observations of Venus have been difficult in the past, due to its extremely dense atmosphere, which is composed primarily of carbon dioxide with a small amount of nitrogen. At 92 bar (9.2 MPa), the atmospheric mass is 93 times that of Earth’s atmosphere and the pressure at the planet’s surface is about 92 times that at Earth’s surface. Venus is also the hottest planet in our Solar System, with a mean surface temperature of 735 K (462 °C/863.6 °F). This is due to the CO²-rich atmosphere which, along with thick clouds of sulfur dioxide, generates the strongest greenhouse effect in the Solar System. Above the dense CO² layer, thick clouds consisting mainly of sulfur dioxide and sulfuric acid droplets scatter about 90% of the sunlight back into space.

Another common phenomena is Venus’ strong winds, which reach speeds of up to 85 m/s (300 km/h; 186.4 mph) at the cloud tops and circle the planet every four to five Earth days. At this speed, these winds move up to 60 times the speed of the planet’s rotation, whereas Earth’s fastest winds are only 10-20% of the planet’s rotational speed. Venus flybys have also indicated that its dense clouds are capable of producing lightning , much like the clouds on Earth. Their intermittent appearance indicates a pattern associated with weather activity, and the lightning rate is at least half of that on Earth. Earth’s Atmosphere: Earth’s atmosphere, which is composed of nitrogen, oxygen, water vapor, carbon dioxide and other trace gases, also consists of five layers. These consists of the Troposphere, the Stratosphere, the Mesosphere, the Thermosphere, and the Exosphere. As a rule, air pressure and density decrease the higher one goes into the atmosphere and the farther one is from the surface.

Closest to the Earth is the Troposphere, which extends from the 0 to between 12 km and 17 km (0 to 7 and 10.56 mi) above the surface. This layer contains roughly 80% of the mass of Earth’s atmosphere, and nearly all atmospheric water vapor or moisture is found in here as well. As a result, it is the layer where most of Earth’s weather takes place. The Stratosphere extends from the Troposphere to an altitude of 50 km (31 mi). This layer extends from the top of the troposphere to the stratopause, which is at an altitude of about 50 to 55 km (31 to 34 mi). This layer of the atmosphere is home to the ozone layer, which is the part of Earth’s atmosphere that contains relatively high concentrations of ozone gas. Space Shuttle Endeavour sillouetted against the atmosphere. The orange layer is the troposphere, the white layer is the stratosphere and the blue layer the mesosphere.

Credit: NASA Next is the Mesosphere, which extends from a distance of 50 to 80 km (31 to 50 mi) above sea level. It is the coldest place on Earth and has an average temperature of around -85 °C (-120 °F; 190 K). The Thermosphere, the second highest layer of the atmosphere, extends from an altitude of about 80 km (50 mi) up to the thermopause, which is at an altitude of 500–1000 km (310–620 mi). The lower part of the thermosphere, from 80 to 550 kilometers (50 to 342 mi), contains the ionosphere – which is so named because it is here in the atmosphere that particles are ionized by solar radiation. This layer is completely cloudless and free of water vapor. It is also at this altitude that the phenomena known as Aurora Borealis and Aurara Australis are known to take place.

The Exosphere, which is outermost layer of the Earth’s atmosphere, extends from the exobase – located at the top of the thermosphere at an altitude of about 700 km above sea level – to about 10,000 km (6,200 mi). The exosphere merges with the emptiness of outer space, and is mainly composed of extremely low densities of hydrogen, helium and several heavier molecules including nitrogen, oxygen and carbon dioxide The exosphere is located too far above Earth for any meteorological phenomena to be possible. However, the Aurora Borealis and Aurora Australis sometimes occur in the lower part of the exosphere, where they overlap into the thermosphere. Photo of the aurora taken by astronaut Doug Wheelock from the International Space Station on July 25, 2010. Credit: NASA/Johnson Space Center The average surface temperature on Earth is approximately 14°C; but as already noted, this varies. For instance, the hottest temperature ever recorded on Earth was 70.7°C (159°F), which was taken in the Lut Desert of Iran.

Meanwhile, the coldest temperature ever recorded on Earth was measured at the Soviet Vostok Station on the Antarctic Plateau, reaching an historic low of -89.2°C (-129°F). Mars’ Atmosphere: Planet Mars has a very thin atmosphere which is composed of 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water. The atmosphere is quite dusty, containing particulates that measure 1.5 micrometers in diameter, which is what gives the Martian sky a tawny color when seen from the surface. Mars’ atmospheric pressure ranges from 0.4 – 0.87 kPa, which is equivalent to about 1% of Earth’s at sea level. Because of its thin atmosphere, and its greater distance from the Sun, the surface temperature of Mars is much colder than what we experience here on Earth.

The planet’s average temperature is -46 °C (51 °F), with a low of -143 °C (-225.4 °F) during the winter at the poles, and a high of 35 °C (95 °F) during summer and midday at the equator. The planet also experiences dust storms, which can turn into what resembles small tornadoes. Larger dust storms occur when the dust is blown into the atmosphere and heats up from the Sun. The warmer dust filled air rises and the winds get stronger, creating storms that can measure up to thousands of kilometers in width and last for months at a time. When they get this large, they can actually block most of the surface from view. Mars, as it appears today, with a very thin and tenuous atmosphere. Credit: NASA Trace amounts of methane have also been detected in the Martian atmosphere, with an estimated concentration of about 30 parts per billion (ppb).

It occurs in extended plumes, and the profiles imply that the methane was released from specific regions – the first of which is located between Isidis and Utopia Planitia (30°N 260°W) and the second in Arabia Terra (0°N 310°W). Ammonia was also tentatively detected on Mars by the Mars Express satellite, but with a relatively short lifetime. It is not clear what produced it, but volcanic activity has been suggested as a possible source. Jupiter’s Atmosphere: Much like Earth, Jupiter experiences auroras near its northern and southern poles. But on Jupiter, the auroral activity is much more intense and rarely ever stops. The intense radiation, Jupiter’s magnetic field, and the abundance of material from Io’s volcanoes that react with Jupiter’s ionosphere create a light show that is truly spectacular. Jupiter also experiences violent weather patterns . Wind speeds of 100 m/s (360 km/h) are common in zonal jets, and can reach as high as 620 kph (385 mph). Storms form within hours and can become thousands of km in diameter overnight.

One storm, the Great Red Spot , has been raging since at least the late 1600s. The storm has been shrinking and expanding throughout its history; but in 2012, it was suggested that the Giant Red Spot might eventually disappear . Jupiter is perpetually covered with clouds composed of ammonia crystals and possibly ammonium hydrosulfide. These clouds are located in the tropopause and are arranged into bands of different latitudes, known as “tropical regions”. The cloud layer is only about 50 km (31 mi) deep, and consists of at least two decks of clouds: a thick lower deck and a thin clearer region. There may also be a thin layer of water clouds underlying the ammonia layer, as evidenced by flashes of lightning detected in the atmosphere of Jupiter, which would be caused by the water’s polarity creating the charge separation needed for lightning. Observations of these electrical discharges indicate that they can be up to a thousand times as powerful as those observed here on the Earth. Saturn’s Atmosphere: The outer atmosphere of Saturn contains 96.3% molecular hydrogen and 3.25% helium by volume.

The gas giant is also known to contain heavier elements, though the proportions of these relative to hydrogen and helium is not known. It is assumed that they would match the primordial abundance from the formation of the Solar System. Trace amounts of ammonia, acetylene, ethane, propane, phosphine and methane have been also detected in Saturn’s atmosphere. The upper clouds are composed of ammonia crystals , while the lower level clouds appear to consist of either ammonium hydrosulfide (NH4SH) or water . Ultraviolet radiation from the Sun causes methane photolysis in the upper atmosphere, leading to a series of hydrocarbon chemical reactions with the resulting products being carried downward by eddies and diffusion. Saturn’s atmosphere exhibits a banded pattern similar to Jupiter’s, but Saturn’s bands are much fainter and wider near the equator. As with Jupiter’s cloud layers, they are divided into the upper and lower layers, which vary in composition based on depth and pressure. In the upper cloud layers, with temperatures in range of 100–160 K and pressures between 0.5–2 bar, the clouds consist of ammonia ice.

Water ice clouds begin at a level where the pressure is about 2.5 bar and extend down to 9.5 bar, where temperatures range from 185–270 K. Intermixed in this layer is a band of ammonium hydrosulfide ice, lying in the pressure range 3–6 bar with temperatures of 290–235 K. Finally, the lower layers, where pressures are between 10–20 bar and temperatures are 270–330 K, contains a region of water droplets with ammonia in an aqueous solution. On occasion, Saturn’s atmosphere exhibits long-lived ovals, similar to what is commonly observed on Jupiter. Whereas Jupiter has the Great Red Spot, Saturn periodically has what’s known as the Great White Spot (aka. Great White Oval). This unique but short-lived phenomenon occurs once every Saturnian year, roughly every 30 Earth years, around the time of the northern hemisphere’s summer solstice. These spots can be several thousands of kilometers wide, and have been observed in 1876, 1903, 1933, 1960, and 1990.

Since 2010, a large band of white clouds called the Northern Electrostatic Disturbance have been observed enveloping Saturn, which was spotted by the Cassini space probe. If the periodic nature of these storms is maintained, another one will occur in about 2020. The winds on Saturn are the second fastest among the Solar System’s planets, after Neptune’s. Voyager data indicate peak easterly winds of 500 m/s (1800 km/h). Saturn’s northern and southern poles have also shown evidence of stormy weather. At the north pole, this takes the form of a hexagonal wave pattern, whereas the south shows evidence of a massive jet stream. The persisting hexagonal wave pattern around the north pole was first noted in the Voyager images. The sides of the hexagon are each about 13,800 km (8,600 mi) long (which is longer than the diameter of the Earth) and the structure rotates with a period of 10h 39m 24s, which is assumed to be equal to the period of rotation of Saturn’s interior.

The south pole vortex, meanwhile, was first observed using the Hubble Space Telescope . These images indicated the presence of a jet stream, but not a hexagonal standing wave. These storms are estimated to be generating winds of 550 km/h, are comparable in size to Earth, and believed to have been going on for billions of years. In 2006, the Cassini space probe observed a hurricane-like storm that had a clearly defined eye. Such storms had not been observed on any planet other than Earth – even on Jupiter. Uranus’ Atmosphere: As with Earth, the atmosphere of Uranus is broken into layers, depending upon temperature and pressure. Like the other gas giants, the planet doesn’t have a firm surface, and scientists define the surface as the region where the atmospheric pressure exceeds one bar (the pressure found on Earth at sea level). Anything accessible to remote-sensing capability – which extends down to roughly 300 km below the 1 bar level – is also considered to be the atmosphere. Diagram of the interior of Uranus. Credit: Public Domain Using these references points, Uranus’ atmosphere can be divided into three layers.

The first is the troposphere, between altitudes of -300 km below the surface and 50 km above it, where pressures range from 100 to 0.1 bar (10 MPa to 10 kPa). The second layer is the stratosphere, which reaches between 50 and 4000 km and experiences pressures between 0.1 and 10-10 bar (10 kPa to 10 µPa). The troposphere is the densest layer in Uranus’ atmosphere. Here, the temperature ranges from 320 K (46.85 °C/116 °F) at the base (-300 km) to 53 K (-220 °C/-364 °F) at 50 km, with the upper region being the coldest in the solar system . The tropopause region is responsible for the vast majority of Uranus’s thermal infrared emissions, thus determining its effective temperature of 59.1 ± 0.3 K. Within the troposphere are layers of clouds – water clouds at the lowest pressures, with ammonium hydrosulfide clouds above them.

Ammonia and hydrogen sulfide clouds come next. Finally, thin methane clouds lay on the top. In the stratosphere, temperatures range from 53 K (-220 °C/-364 °F) at the upper level to between 800 and 850 K (527 – 577 °C/980 – 1070 °F) at the base of the thermosphere, thanks largely to heating caused by solar radiation. The stratosphere contains ethane smog, which may contribute to the planet’s dull appearance. Acetylene and methane are also present, and these hazes help warm the stratosphere. Uranus, as imaged by the Hubble Space Telescope. Image credit: NASA/Hubble The outermost layer, the thermosphere and corona, extend from 4,000 km to as high as 50,000 km from the surface. This region has a uniform temperature of 800-850 (577 °C/1,070 °F), although scientists are unsure as to the reason.

Because the distance to Uranus from the Sun is so great, the amount of sunlight absorbed cannot be the primary cause. Like Jupiter and Saturn, Uranus’s weather follows a similar pattern where systems are broken up into bands that rotate around the planet, which are driven by internal heat rising to the upper atmosphere. As a result, winds on Uranus can reach up to 900 km/h (560 mph), creating massive storms like the one spotted by the Hubble Space Telescope in 2012. Similar to Jupiter’s Great Red Spot, this “ Dark Spot ” was a giant cloud vortex that measured 1,700 kilometers by 3,000 kilometers (1,100 miles by 1,900 miles). Neptune’s Atmosphere: At high altitudes, Neptune’s atmosphere is 80% hydrogen and 19% helium, with a trace amount of methane. As with Uranus, this absorption of red light by the atmospheric methane is part of what gives Neptune its blue hue, although Neptune’s is darker and more vivid. Because Neptune’s atmospheric methane content is similar to that of Uranus, some unknown constituent is thought to contribute to Neptune’s more intense coloring.

Neptune’s atmosphere is subdivided into two main regions: the lower troposphere (where temperature decreases with altitude), and the stratosphere (where temperature increases with altitude). The boundary between the two, the tropopause, lies at a pressure of 0.1 bars (10 kPa). The stratosphere then gives way to the thermosphere at a pressure lower than 10-5 to 10-4 microbars (1 to 10 Pa), which gradually transitions to the exosphere. Neptune’s spectra suggest that its lower stratosphere is hazy due to condensation of products caused by the interaction of ultraviolet radiation and methane (i.e. photolysis), which produces compounds such as ethane and ethyne. The stratosphere is also home to trace amounts of carbon monoxide and hydrogen cyanide, which are responsible for Neptune’s stratosphere being warmer than that of Uranus. A modified color/contrast image emphasizing Neptune’s atmospheric features, including wind speed. Credit Erich Karkoschka) For reasons that remain obscure, the planet’s thermosphere experiences unusually high temperatures of about 750 K (476.85 °C/890 °F).

The planet is too far from the Sun for this heat to be generated by ultraviolet radiation, which means another heating mechanism is involved – which could be the atmosphere’s interaction with ion’s in the planet’s magnetic field, or gravity waves from the planet’s interior that dissipate in the atmosphere. Because Neptune is not a solid body, its atmosphere undergoes differential rotation. The wide equatorial zone rotates with a period of about 18 hours, which is slower than the 16.1-hour rotation of the planet’s magnetic field. By contrast, the reverse is true for the polar regions where the rotation period is 12 hours. This differential rotation is the most pronounced of any planet in the Solar System, and results in strong latitudinal wind shear and violent storms. The three most impressive were all spotted in 1989 by the Voyager 2 space probe, and then named based on their appearances. The first to be spotted was a massive anticyclonic storm measuring 13,000 x 6,600 km and resembling the Great Red Spot of Jupiter. Known as the Great Dark Spot , this storm was not spotted five later (Nov.

2nd, 1994) when the Hubble Space Telescope looked for it. Instead, a new storm that was very similar in appearance was found in the planet’s northern hemisphere, suggesting that these storms have a shorter life span than Jupiter’s. Reconstruction of Voyager 2 images showing the Great Black spot (top left), Scooter (middle), and the Small Black Spot (lower right). Credit: NASA/JPL The Scooter is another storm, a white cloud group located farther south than the Great Dark Spot – a nickname that first arose during the months leading up to the Voyager 2 encounter in 1989. The Small Dark Spot , a southern cyclonic storm, was the second-most-intense storm observed during the 1989 encounter. It was initially completely dark; but as Voyager 2 approached the planet, a bright core developed and could be seen in most of the highest-resolution images. In sum, the planet’s of our Solar System all have atmospheres of sorts. And compared to Earth’s relatively balmy and thick atmosphere, they run the gamut between very very thin to very very dense. They also range in temperatures from the extremely hot (like on Venus) to the extreme freezing cold.

And when it comes to weather systems, things can equally extreme, with planet’s boasting either weather at all, or intense cyclonic and dust storms that put storms here n Earth to shame. And whereas some are entirely hostile to life as we know it, others we might be able to work with. We have many interesting articles about planetary atmosphere’s here at Universe Today. For instance, he’s What is the Atmosphere? , and articles about the atmosphere of Mercury , Venus , Mars , Jupiter , Saturn , Uranus and Neptune , Venus' Atmosphere: Composition, Climate and Weather Venus' Atmosphere: Composition, Climate and Weather By Nola Taylor Redd, Space.com Contributor | November 16, 2012 06:23pm ET MORE Venus has the distinction of being the hottest planet in the solar system, and the fault lies solely with its atmosphere. What is it about the air on Venus that keeps the planet cooking? False-colour image of cloud features seen on Venus by the Venus Monitoring Camera (VMC) on Venus Express. Credit: ESA/MPS/DLR/IDA Atmospheric makeup The atmosphere of Venus is made up almost completely of carbon dioxide. Nitrogen exists in small doses, as do clouds of sulfuric acid.

The air of Venus is so dense that the small traces of nitrogen are four times the amount found on Earth, although nitrogen makes up more than three-fourths of the terrestrial atmosphere. This composition causes a runaway greenhouse effect that heats the planet even hotter than the surface of Mercury, although Venus lies farther from the sun . When the rocky core of Venus formed , it captured much of the gas gravitationally. In addition to warming the planet, the heavy clouds shield it, preventing visible observations of the surface and protecting it from bombardment by all but the largest meteorites. Although Venus and Earth are similar in size , someone standing on the ground on Venus would experience air about 90 times heavier than Earth's atmosphere; pressures are similar to diving 3,000 feet beneath the ocean. Ironically, the most Earth-like atmosphere in the solar system occurs 30 to 40 miles (50 to 60 kilometers) above the surface of Venus. Both oxygen and hydrogen rise above the heavier gas layer covering the ground, and the pressures are similar to our planet.

Carbon dioxide: 96 percent NASA - The Five Most Abundant Gases in the Martian Atmosphere › Full Size › 800 x 600 The Five Most Abundant Gases in the Martian Atmosphere This graph shows the percentage abundance of five gases in the atmosphere of Mars, as measured by the Quadrupole Mass Spectrometer instrument of the Sample Analysis at Mars instrument suite on NASA's Mars rover in October 2012. The season was early spring in Mars' southern hemisphere, and the location was inside Mars' Gale Crater, at 4.49 degrees south latitude, 137.42 degrees east longitude. The graph uses as logarithmic scale for volume percentage of the atmosphere so that these gases with very different concentrations can all be plotted. By far the predominant gas is carbon dioxide, making up 95.9 percent of the atmosphere's volume. The next four most abundant gases are argon, nitrogen, oxygen and carbon monoxide. Researchers will use SAM repeatedly throughout Curiosity's mission on Mars to check for seasonal changes in atmospheric composition.

Image Credit: NASA/JPL-Caltech, SAM/GSFC Terrestrial Planet Atmospheres Primary Atmospheres: The primary atmosphere for every terrestrial world was composed mostly of light gases that accreted during initial formation. These gases are similar to the primordial mixture of gases found in the Sun and Jupiter . That is 94.2% H, 5.7% He and everything else less that 0.1%. However, this primary atmosphere was lost on the terrestrial planets. Why? a combination of surface temperature, mass of the atoms and escape velocity of the planet. What determines if a particular atom is retained by a planet's gravitational field? if the atom is moving less than the escape velocity for the planet, it stays. If it moves faster than escape velocity, it escapes into outer space. From the kinetic theory of gases, we know that the mean velocity of a bunch of atoms is set by the temperature of the planet's surface. Remember our microscopic description of macroscopic quantities such as pressure and temperature. Higher temperatures translate into higher velocities for the atoms. Now consider of mix of elements in an atmosphere. Some atoms/molecules are low in mass (H, He) some are heavy (CO2, H2O, etc).

The light elements are moving faster than the heavy elements and can reach escape velocity. The second variable is the surface temperature of the planet. The inner worlds are closer to the Sun, therefore warmer. The opposite is true of the outer planets, farther from the Sun therefore cooler. Combining the variables of escape velocity (mass, radius of planet) and surface temperature (distance from Sun plus effects of atmosphere heating) produces the following diagram. For key elements, lines are draw to show where the element escapes from the planet. If a planet is below that line, that element will escape. So note that for the outer Jovian worlds, all the primary, initial atmosphere is held. But for the inner worlds, most of the original H and He has been lost. These inner worlds then will form a secondary atmosphere composed of the outgassing from tectonic activity. Secondary Atmospheres: For the warmer terrestrial worlds, the light, gaseous elements (H, He) are lost. The remaining elements are grouped into the rocky materials (iron, olivine, pyroxene) and the icy materials (H2O, CO2, CH4, NH3, SO2).

The icy materials are more common in the outer Solar System, they are delivered to the inner Solar System in the form of comets (see later lecture). The rocky and icy materials mix in the early crust and mantle. If the planet cools quickly, there is little to no tectonic activity and the icy materials are trapped in the mantle (see for example the Galilean moons). If the planet has a large mass (which means lots of trapped heat from formation), then there is a large amount of tectonic activity -> volcanos. The icy materials are turned to gases in the warm mantle and returned to the planet surface in the form of outgassing to produce a secondary atmosphere . The atmospheres of Venus, Earth and Mars are secondary atmospheres. The composition of outgassing is similar for Venus, Earth and Mars and is composed of 58% H2O, 23% CO2, 13% SO2, 5% N2 and traces of noble gases (Ne, Ar, Kr). The latter evolution of this outgassing is driven primarily by the surface temperature and chemistry of the planet. Note that H2O is the key catalyst for the evolution of a secondary atmosphere.

On the Earth, the temperature was just right for the formation of liquid water = oceans. The CO2 released by outgassing was dissolved in the liquid water to produce carbonate rocks. Thus, the Earth had a reducing atmosphere. On both Venus there was no liquid water (too hot) and, therefore, no place for the CO2 to dissolve. If the atmosphere is reducing in CO2 than lower ranking elements become important once the CO2 is gone. For the Earth, this meant that the atmosphere became primarily N2 based, with later additions of O2 from lifeforms. On Venus, CO2 was not reduced and stayed as the primary component to their atmospheres. On Mars there was a period of liquid water very soon after formation. But there was insufficient temperature for this water to remain as a liquid, so it froze out leaving CO2 as the primary component in the atmosphere. Also note how the noble gases are good traces of the amount of evolution an atmosphere undergoes. Noble gases do not react with other elements (they are inert). An atmosphere that is thin and undergoes sharp changes in mass has a high percentage of noble gases.

In this case, Mars has had most of its atmosphere frozen out in the form of H2O and CO2 ice, leaving a high amount of noble gases. Thick atmospheres, such as Venus, have small percentages of noble gases since most of the outgassing material remains on the planet surface. Earth's Oxygen: Note that most of the O2 released by outgassing is locked up in liquid H2O. Since O2 is highly reactive, it must constantly be replenished. Some is released by photodisintegration with H2O vapor in the upper atmosphere. But most of the O2 in today's atmosphere is from the photosynthesis process associated with lifeforms. This occurred about 1 billion years after the Earth formed. The original secondary atmosphere of the Earth was lacking large amounts of O2 and was rich in N2 and CO2. Greenhouse changes: The greenhouse effect is controlled by the amount (by mass) of greenhouse gases in an atmosphere. These gases are primarily H2O, CO2, CH4, NH3.

For secondary atmospheres on Venus, Earth and Mars, only CO2 has a major contribution to the greenhouse effect (although note that the amount of CH4 is increasing on the Earth due to the waste products of animals and agriculture). The greenhouse effect currently raises the temperature of Venus, Earth and Mars by the following amounts: Mars -> +5 degrees Earth -> +35 degrees Venus -> +500 degrees Note that the greenhouse effect for the Earth is just enough to keep us out of a perpetual Ice Age (a little greenhouse effect is good for you). Whereas for Venus, a severe runaway greenhouse effect makes it the hottest place in the Solar System. Also note that Mars probably had a stronger greenhouse effect in its distant past. But the large amounts of CO2 were converted to rocks in the early Mars oceans. The atmosphere thinned too fast stopping the greenhouse effect and the liquid H2O turned to ice (cold death). The lesson to learn here is that Mars and Venus are exactly opposite in their evolution and the result of the greenhouse effect. The dynamics of planetary atmosphere's are unstable, and complex so that changes in Earth's atmosphere, even small, are a very serious matter for those of us who need a place to live.

Titan's atmosphere: One of the thickest atmosphere's in the Solar System (2nd only to Venus) is Titan. Titan's current atmosphere is 90% N2 and 7% CH4 (methane). Since Titan formed in the outer Solar System where it is much cooler, and contains more icy materials such as NH3 (ammonia) and CH4. NH3 is easily separated into N2 and H2 by sunlight. The N2 is retained by Titan's gravity (see the chart above), but H2 escapes. Thus, over time, Titan has built up a N2 atmosphere like the Earth's from an original secondary atmosphere that was rich in NH3. Note that the interaction of sunlight and CH4 induces chemical reactions that build hydrocarbons such as ethane, acetylene, propane; all of which have been detected in Titan's atmosphere. Hydrocarbons can join together to form long molecular chains called polymers. Droplets of polymers can remain suspended in an atmosphere to form an aerosol (heavy smog) whereas others will sink to form a thick layer of tar on the surface.

Composition of a Secondary Atmosphere: In summary, the composition of an atmosphere on a terrestrial planet will be determined by the following: Distance from Sun (surface temperature of planet) Mass and radius of planet = surface gravity = escape velocity chemical reactions = different molecules are created and destroyed in various environments, higher temperatures mean faster reactions geological activity = amount of outgassing, more activity = more outgassing = thicker atmosphere living organisms = change the composition through their waste products Why are Terrestrial Planets small and rocky? The primary atmosphere has boiled off leaving the rocky core. Why did this happen? Distance from the Sun for the primary worlds, distance from warm Jupiter or Saturn for the terrestrial moons.

Question: What gas is the main component of the atmosphere of the planet Mars?
Answer: Carbon dioxide