Is One Quarter The Size Of Earth, Has No Moons, And Has An Almost Non-existent Atmosphere
- Do other planets have conditions like Earth? Do they accept storms, rain, hurricanes, lightning, or snow? Does Mercury or the Moon take an temper? Is there current of air on the Moon?
- question from Paul Metcalf, Tansha & Ramesh
Mercury is the but planet with no real atmosphere to speak of. The world is likewise small with gravity as well weak to hold on to big quantities of atmospheric gas. However, Mercury does maintain a very thin and transitory atmosphere consisting of a varied array of gases. Major constituents include potassium, sodium, oxygen, helium, hydrogen, and water vapor. Researchers are not entirely sure what produces this atmosphere, just the leading theory is that it comes from the solar wind, outgassing due to radioactive decay from the surface, and comet impacts. The solar wind brings hydrogen and helium blasted from the Sun into Mercury's weak magnetic field where the atoms are slowed downward enough to exist temporarily captured past the planet'south gravitational field. Sodium and potassium are probably the result of radioactive disuse while other elements and water vapor may be deposited past comets striking the planet.
Photo mosaic of Mercury created from Mariner 10 imagery
All the same, Mercury is very hot given its close proximity to the Sun. This heat increases the free energy of the atoms and molecules in the tenuous atmosphere then they speedily escape Mercury's weak gravitational attraction and caput off into space. The solar wind continuously replenishes the atmosphere, just these gases cannot accumulate and the atmosphere remains well-nigh nonexistent compared to larger planets. As a consequence, Mercury does not feel weather and has no winds to speak of. The temperature on its surface is dictated purely by exposure to sunlight, ranging from a elevation of 430�C (805�F) along the equator facing the Sun to equally low as -180�C (-290�F) in permanently shadowed craters at the poles.
Venus, meanwhile, has the densest and perhaps the most hostile atmosphere of whatever planet in the solar system. Scientists speculate that Venus and Globe had very similar atmospheres early in their histories, only the two worlds accept taken drastically different paths since. Existence closer to the Dominicus, Venus receives considerably more than heating than Earth. This solar energy likely evaporated liquid water on its surface, and water vapor traps heat causing temperatures to rise. The increasing temperature released carbon dioxide from surface rocks thickening the atmosphere and raising temperatures even higher. This repeating cycle somewhen reached a critical level turning the Venutian atmosphere into a furnace.
Cloud structure on Venus as seen in ultraviolet light
The atmosphere is nigh entirely carbon dioxide with minor amounts of nitrogen and numerous other gases. The dense atmosphere gives the planet a surface temperature hot enough to cook atomic number 82 and a pressure more than 90 times greater than Earth'due south. Venus is also surrounded by thick permament clouds of sulfur dioxide and sulfuric acid that grade loftier in the temper and cake most sunlight from reaching the surface. The lite that does filter through is converted to heat that is unable to radiate dorsum through the deject layer, thereby maintaining the stifling weather condition. This upshot continues solar day and night such that temperature around the earth remains nearly constant at a blistering 460�C (865�F). The constant temperature profile in the lower atmosphere eliminates all merely very light winds, only wind speeds of more than than 300 km/h (185 mph) take been measured at the top of the cloud layer.
The same greenhouse effect that doomed Venus has instead made Globe warm enough for complex life to develop and thrive. Scientists believe Earth's atmosphere was originally a toxic combination of carbon, hydrogen, oxygen, and nitrogen compounds but the development of early plants inverse the composition of the atmosphere into 1 capable of supporting brute life. Today'due south atmosphere predominantly consists of nitrogen and oxygen with pocket-sized amounts of the greenhouse gases carbon dioxide, water vapor, and methane. These gases trap enough thermal free energy from the Lord's day to raise the atmospheric temperature and maintain it inside a habitable range over most of the planet'due south surface day or nighttime.
Earth's blueish atmosphere above the tops of h2o ice clouds
Temperature extremes on Earth vary from a peak of 58�C (136�F) measured in Decease Valley, California, in the summer to as low as -88�C (-126�F) in Antarctica. Yet, extremes like these are rare and the mean surface temperature across the globe is a comfortable xiv�C (57�F). Without the effect produced by atmospheric gases that trap heat, yet, the average surface temperature would plummet to -xviii�C (0�F) and would likely exist likewise cold for complex life to take developed. Current of air speeds at the surface are generally low just can reach nearly 320 km/h (200 mph) in hurricanes or cyclones, the worst storms experienced on the planet. The highest speeds on an average day can be institute high in the atmosphere in a region chosen the jet stream where sustained winds of 55 to 120 km/h (35 to 75 mph) are typical.
While Venus and Globe owe their atmospheric properties in large part to the then-chosen greenhouse effect, the same cannot be said for Mars. Many scientists believe Mars once had an temper dense plenty and warm enough to back up large bodies of liquid h2o on its surface. The planet has since lost its magnetic field allowing the solar wind to strip away textile from the atmosphere reducing its density and pressure. The Martian temper is at present very thin with a surface pressure less than 1% that of World. The predominant substance composing the atmosphere is carbon dioxide with small amounts of nitrogen and other gases.
Photo of Martian clouds taken by the Hubble Space Telescope
Given the planet'south distance from the Sun, Mars receives less solar free energy than World and its thin temper is unable to trap much estrus. Temperatures on Mars boilerplate simply -46�C (-51�F). The coldest temperatures can be found at the poles during the Martian winter when the surface drops as depression equally -87�C (-125�F). This is then cold that as much equally a quarter of the temper freezes into slabs of dry ice increasing the size of the polar ice caps. Rising temperatures cause the frozen carbon dioxide to sublime back into gas generating stiff winds and dust storms. Current of air speeds as high equally 480 km/h (300 mph) have been measured racing from the poles towards the equator stirring up great clouds of dust and creating wispy clouds of water ice.
The term atmosphere becomes more difficult to ascertain for the outer planets, known as gas giants. Dissimilar the inner terrestrial planets, these worlds have no obvious surface dividing the solid planet from the gaseous atmosphere. Information technology is believed these planets are equanimous of layers of increasing pressure level and density. These layers range from a gaseous outer temper to a liquid mantle to a solid core. For the sake of this discussion, nearly sources refer to "surface" weather condition like pressure and temperature at the top of the cloud layer, the everyman office of the planet visible from space.
Theoretical structure of the gas giants exemplified by Neptune
The atmospheres of all four gas giants are generally similar and are dominated by the gases hydrogen and helium. The atmospheres also contain substances like ammonia, sulfur, and methane that create the colors these planets are known for. These worlds are also quite cold given their distance from the Sun, but all are considerably warmer than the solar free energy they receive can account for. The leading theory to explicate the college temperatures is that the giants generate considerable internal estrus as they contract under the force of gravity. Friction created by precipitation of heavier elements through the light hydrogen atmosphere or radioactive decay of elements like uranium at the core may besides be responsible for some of the interior heating.
One of the features distinguishing the atmospheres of the gas giants is the presence of lighter and darker bands of differing colors. These bands are created by diverse clouds composed of different substances at different altitudes and rotating around the planet at unlike rates. The rotation every bit well as upward motion of clouds into higher regions of the atmosphere is driven by convection currents due to differences in atmospheric heating. Bands are least obvious on Uranus since the planet is tilted on its side and its poles confront the Sun during much of its orbit. This inclination reduces the convection upshot, though contempo Hubble Space Telescope imagery suggests banding is more than prevalent now that the equatorial region of Uranus is facing the Sun.
Cloud bands of Saturn enhanced by ultraviolet, violet, and green filters
The interaction of different layers of the temper driven by this convection too creates turbulence and often generates strong winds and intense storms. The largest storm ever seen is Jupiter'due south Great Red Spot that has existed at to the lowest degree as long as humans have been able to observe information technology. The storm is three times larger than Earth and circles Jupiter'south southern hemisphere is just half-dozen days. Jupiter is as well covered by many smaller storms, some of which appear and disappear within hours while others last for centuries. Like storms accept also been observed on the other gas giants, including Saturn's Cracking White Spot and Neptune'due south Smashing Dark Spot, though these are generally much smaller and less stable than Jupiter's mighty tempests.
Accompanying these turbulent storms are intense winds. Current of air speeds of 360 km/h (225 mph) are routine in Jupiter's zonal jets while peak winds tin can reach 545 km/h (340 mph). Winds on Uranus are generally milder for the same reasons it has less intense bands of clouds than other gas giants, just maximum speeds of 580 km/h (360 mph) accept been observed. Winds on Jupiter and Uranus stake in comparison to those of the other gas giants, notwithstanding. The Voyager 2 spacecraft detected easterly winds on Saturn of ane,800 km/h (1,120 mph), but the record for windiest temper in the solar system belongs to Neptune at a whopping 2,100 km/h (one,300 mph).
Jupiter's Great Red Spot and numerous smaller storms
In addition to the worlds already discussed, several moons circling the planets possess atmospheres as well. Most of these are similar to the thin and well-nigh nonexistent atmosphere of Mercury. Earth's Moon, for example, has an extremely tenuous atmosphere consisting mostly of byproducts from radioactivity or bombardment of meteorites and the solar wind. The verbal limerick is variable and may consist of gases including sodium, potassium, radon, polonium, argon, helium, oxygen, methane, carbon monoxide, or carbon dioxide.
Several of Jupiter's moons besides possess a sparse temper. Io's tenuous atmosphere is primarily made up of sulfur dioxide from volcanic eruptions, simply information technology is quickly stripped away past intense radiations from Jupiter and must be constantly replenished. The atmospheres of Europa and Ganymede are predominantly oxygen, only unlike Earth'due south oxygen that is created by plants, the gases are generated by charged particles striking the icy surfaces on the moons and splitting water into hydrogen and oxygen. The calorie-free hydrogen atoms escape the weak gravitational attraction leaving the oxygen behind. Callisto likewise has a thin carbon dioxide atmosphere believed to come up from the dull sublimation of dry ice on its surface.
Saturn's moon Enceladus and Neptune'due south moon Triton also have very thin atmospheres of like origins as Jupiter's moon Io. That of Enceladus appears to be the result of volcanoes in the southern hemisphere that spew geysers of h2o mixed with nitrogen, carbon dioxide, and methane. Triton likewise has geysers that erupt plumes of nitrogen and methane.
Hazy orange temper of Saturn'due south moon Titan photographed by Cassini
Like Mercury, the atmospheres of all of these moons are besides thin to generate whatever winds or weather to speak of. The just moon with a fairly thick temper is Saturn's largest satellite Titan. Titan'south atmosphere is even denser and produces a greater surface pressure than Earth's. Composed by and large of nitrogen with small amounts of methyl hydride and numerous other gases, the atmosphere reflects most sunlight producing an "anti-greenhouse effect" that cools the surface. This miracle makes Titan a very cold globe with an average surface temperature of just -183�C (-298�F). In 2005, NASA and the European Infinite Agency successfully dropped the Huygens lander through Titan's atmosphere to touch down on its frozen surface. Huygens detected very little air current on the surface, merely speeds equally high every bit 435 km/h (270 mph) were measured at loftier distance. The strong winds appear to be generated past tidal forces from Saturn and produce large wind-blown sand dunes forming in parallel west-to-east lines.
Other objects in the solar arrangement that may possess atmospheres include three bodies recently classified as dwarf planets. The closest to Earth is the asteroid Ceres, the largest asteroid in the solar arrangement residing in the belt betwixt Mars and Jupiter. At that place are indications Ceres may take a thin atmosphere, simply its exact nature has however to be determined. The all-time-known dwarf planet is the one-time planet Pluto. This distant world is believed to exist covered in ices that melt as Pluto approaches the Sun in its eccentric orbit. The sublimated gases include nitrogen, methane, and carbon monoxide that form a tenuous atmosphere. Every bit Pluto moves further from the Lord's day, these gases probably once more freeze to the surface. Pluto's temper was get-go detected in 1985 and continued to strengthen through 2002. NASA'south New Horizons spacecraft will achieve Pluto in 2015 and should be able to direct observe its atmosphere for the first fourth dimension.
Highly eccentric orbit of Eris effectually the Lord's day
The largest of the dwarf planets is the recently discovered Eris. Eris likely shares a similar limerick equally Pluto with large quantities of frozen methane and other ices on its surface. The body follows a very unusual orbit that brings information technology almost every bit close to the Lord's day as Pluto but also far into the outer regions of the solar system. Eris is currently well-nigh its maximum distance from the Sun, but every bit it approaches closer in some 250 years or so, information technology is probable that some of the ices on its surface volition thaw to create a thin temper.
The atmospheric backdrop of the worlds described in a higher place are summarized and compared in the following tabular array. The table includes the limerick of the temper and the typical pressure constitute at the surface as well equally extremes of temperature and current of air.
| Planet | Atmosphere | Surface Temperature | Max Wind Speeds | |||
|---|---|---|---|---|---|---|
| Surface Force per unit area | Composition | Depression | Average | High | ||
| Mercury | Negligible | 32% Potassium 25% Sodium ten% Diminutive Oxygen 7% Argon 6% Helium vi% Molecular Oxygen 5% Nitrogen 4% Carbon Dioxide 3% Water Vapor 3% Hydrogen | -180�C -290�F | 65�C 150�F | 430�C 805�F | n/a |
| Venus | ix,300 kPa i,350 psi | 96% Carbon Dioxide four% Nitrogen | ? | 460�C 865�F | ? | 300-355 km/h 185-220 mph |
| Globe | 101.three kPa 14.vii psi | 78% Nitrogen 21% Oxygen one% Argon | -88�C -126�F | fourteen�C 57�F | 58�C 136�F | 120-305 km/h 75-190 mph |
| Mars | 0.9 kPa 0.thirteen psi | 96% Carbon Dioxide three% Nitrogen 1% Argon 0.2% Oxygen | -87�C -125�F | -46�C -51�F | -5�C 23�F | 400-480 km/h 250-300 mph |
| Jupiter | 200 kPa 29 psi | 86% Hydrogen 13% Helium 0.ane% Methane 0.i% Water Vapor | -163�C -262�F | -121�C -186�F | 205�C 400�F | 465-545 km/h 290-340 mph |
| Saturn | 140 kPa twenty.3 psi | 93% Hydrogen 7% Helium 0.ii% Methane 0.1% Water Vapor | -192�C -312�F | -130�C -202�F | ? | 1,800 km/h 1,120 mph |
| Uranus | 120 kPa 17.4 psi | 83% Hydrogen xv% Helium 2% Methane | -218�C -361�F | -205�C -337�F | ? | 145-580 km/h xc-360 mph |
| Neptune | 100 kPa fourteen.v psi | 80% Hydrogen 19% Helium two% Methyl hydride | -223�C -370�F | -220�C -364�F | -218�C -361�F | 2,100 km/h 1,300 mph |
| Moon | Atmosphere | Surface Temperature | Max Wind Speeds | |||
| Surface Pressure | Composition | Low | Average | High | ||
| Moon (Earth) | Negligible | Sodium Potassium Argon Helium | -203�C -334�F | -53�C -64�F | 117�C 242�F | n/a |
| Io (Jupiter) | Negligible | 90% Sulfur Dioxide | ? | -143�C -226�F | -73�C -100�F | northward/a |
| Europa (Jupiter) | Negligible | 100% Oxygen | -223�C -370�F | -170�C -274�F | -148�C -235�F | n/a |
| Ganymede (Jupiter) | Negligible | 100% Oxygen | ? | -164�C -263�F | ? | north/a |
| Callisto (Jupiter) | Negligible | 100% Carbon Dioxide | ? | -153�C -244�F | ? | due north/a |
| Enceladus (Saturn) | Negligible | 91% Water Vapor four% Nitrogen iii% Carbon Dioxide ii% Methane | -240�C -400�F | -198�C -325�F | -128�C -199�F | n/a |
| Titan (Saturn) | 147 kPa 21.iii psi | 98% Nitrogen 2% Marsh gas | ? | -183�C -298�F | ? | 435 km/h (270 mph) |
| Triton (Neptune) | Negligible | 100% Nitrogen 0.1% Methane | ? | -239�C -398�F | ? | n/a |
| Dwarf Planet | Atmosphere | Surface Temperature | Max Wind Speeds | |||
| Surface Pressure | Limerick | Depression | Average | High | ||
| Ceres | Negligible | ? | ? | -106�C -159�F | -34�C -29�F | n/a |
| Pluto | 0.0003 kPa 0.00004 psi | Nitrogen Methane Carbon Monoxide | -240�C -400�F | -229�C -380�F | -218�C -361�F | north/a |
| Eris | Negligible? | ? | ? | -243�C -406�F | ? | n/a |
In addition to the planets, the solar system itself experiences "weather" of sorts. This conditions results from atmospheric condition at the surface of the Sun that generates solar flares and the solar current of air. These phenomena tin can touch on atmospheric weather and weather condition on the planets and may as well produce interference in World satellites and communications systems. Larn more than at a dainty site called SpaceWeather.com that provides solar organisation "meteorology" predictions.
- reply by Molly Swanson , 13 May 2007
Related Topics:
- What are the colors of the planets?
I heard that some people think Pluto shouldn't be called a planet. Someone also found a new object fifty-fifty bigger than Pluto that may or may not be a planet. It'due south all then disruptive! Tin you please explicate?
How can I summate the speed of sound on Mars?
Read More Manufactures:
- Current Question of the Week
- Past Question Archive
- Most Popular Questions
- Search the Archive
- Submit a Question
Is One Quarter The Size Of Earth, Has No Moons, And Has An Almost Non-existent Atmosphere,
Source: http://www.aerospaceweb.org/question/atmosphere/q0306.shtml
Posted by: esquivelsest1967.blogspot.com
0 Response to "Is One Quarter The Size Of Earth, Has No Moons, And Has An Almost Non-existent Atmosphere"
Post a Comment