Theory 
Solar System Planets| CONTENT - A general view of the 9 planets of our solar system |
Central to early astronomy were observations of the five starlike objects that moved against the background stellar tapestry, hence called from a Greek word meaning 'wanderers,' or planets. The planets were associated with gods as their names we use today are from Roman mythology. After a long lull, planets were then the first targets of Italian scientist Galileo Galilei with his telescope in the early 1600's, and planets became other worlds. The development of larger telescopes led to the discovery of Uranus in the late 1700s and Neptune in the mid-1800's. The solar system’s got more complicated with the discovery of the minor planets at the beginning of the 1800's. Planets were little by little forgotten to the benefit, since the late 1800's, of stellar astrophysics and cosmology but they eventually got a huge and unexpected boost in the 1950's due to the advent of the Space Age. As our Milky Way’s star formation frenzy peaked 10 billion years ago, Sun did not form until roughly 4.5 billion years ago. Sun’s late appearance may actually have fostered the growth of our solar system’s planets as elements heavier than hydrogen and helium had turned more abundant. The solar sytem had been born 4.5 billion years ago, when the Sun formed from a gas and dust nebula. Such locations are the coldest ones in the Universe, like dark and dusty nurseries as they are termed 'cold cores', technically. As the cloud shrinked more and more under its own gravity, with two polar jets appearing, the star eventually ignited, with the remaining dust and gas flattening into a disk in the equatorial plane, forming a 'protoplanetary disk.' Our Sun contains a lot more heavy elements than it should based on its current position in the local galactic environment hence the Sun was either born closer to the center of our Milky Way Galaxy, or there were once exploding stars nearby that enriched the solar nebula with heavy elements. Recentest data are hinting to a age of 4.5682 billion years for the solar system, the best estimate so far and pulling that age back by some 1.9 million years from previous thinking. Such a new limit is hinting further to minerals present in different quantities at the origin of the solar system. A larger amount of iron-60 might well hint to that a supernova explosion might have occurred close to where our Sun and planets were forming that strongly warmed the medium and helped nascent planets to differentiate. Calcium and aluminum-rich rocks are thought to be the first solid rocks to condense out of the protoplanetary disk. The age of our solar system may be determined through minerals contained in meteorites falling on the Earth. The jets, at the same times died out. That disk of gas and dust splitted and gravitational instabilities formed smaller bodies. Through further accretion and collisions, such bodies eventually formed the nine planets over the course of some tens of millions years. As the Sun continued to form, its radiation and heat blew the most volatile elements off the inner regions of the solar system with the planets forming near the Sun mainly formed upon heavy metallic and silicate elements, as further planets forming upon more volatile elements, like ice and gas. The formation of planets began as our Sun still did not had reached its internal nuclear fusion, which occurred by about 70 millions years after the cloud collapsed. Usually, the gas giants are thought to form first, then the telluric planets. Earth formed from Mars-sized or moon-sized bodies smacking together. Solid materials and gravitation further produced a dynamical interior at the inner, rocky planets. They heated, melted, and layered, a process called differentiation. Gas giants, as far as they are concerned, accreted gas layers around a solid, proto-planet core. Once they had been born, the telluric planets endured a period of heavy bombardment, the 'Late Heavy Bombardment,' about 4 billion years ago, as numerous leftovers had been left from the planets' formation. Before that, the gas giants had influenced the fate of numerous small planetesimals left in the solar system. The ones found in the Asteroid Belt, where the gravity of Jupiter prevented those of accreting into more planets, and the one in the Kuiper Belt, by the outreach of the solar system, which was too far apart from each other to do so and directed by Neptune. Jupiter and the gas giants further either ejected large parts of both belts objects inside, or outside of the solar system, as the gravity exchanges which occurred from that also moved Jupiter and the three other giant planets at their definitive location. Those asteroids were swept away by the newly formed inner planets as a flurry of comets and asteroids just punched all of them and their moons. Such a bombardment, on the other hand, brought to the planets the buildings blocks of life, like water and fundamental molecules. Once the leftovers evacuated, the solar system, as we know it, emerged definitively, with the planets, from Mercury to Pluto, the asteroid belt between Mars and Jupiter, and two faraway belts -the Kuiper Belt and the Oort Cloud- of primordial, remaining, materials and bodies. Heat generated by the gravitational pull of moons formed from massive collisions could extend the lifetimes of liquid water oceans beneath the surface of large icy worlds in our outer solar system, or the Trans-Neptunian Objects (TNOs) -- of them Pluto. The solar system features a dust disk that extends out from near the Sun all the way to the Kuiper Belt, and possibly beyond. Past Jupiter, this dust disk is comprised of material primarily shed from Kuiper Belt objects. As seen from away, the nine planets are too faint to see as a observer would note the solar system’s dust disk. Far from being empty, the space surrounding planets in our solar system is filled with fast moving particles and a complex electromagnetic system often driven by the Sun In terms of dimensions, the solar system, based on where the planets end, is ending by Neptune and the Kuiper Belt as the edge of the Sun's magnetic fields lies at the heliosphere. It you consider the stopping point of Sun's gravitational influence, the solar system would end at the Oort Cloud
->How Did the Solar System Evolve? A recent study, in 2007, modelized a possible evolution of the solar system, with the protoplanetery gas and dust cloud having lasted for about 10 million years while the gas giants, like Neptune and Uranus were close together and close to the Sun and Jupiter and Saturn amazingly featuring a sole mass. At that time, gravitational interactions with a primitive form of the Kuiper Belt, which was larger at the time, ended up with Jupiter moving closer to the Sun, and the other three gas giants moving outwards, and between themselves (each time some object of the belt was ejected, that allowed for some move by the gas giants). The move too, acted upon the early formation of the asteroid belt, with the 'Kirkwood gaps' (discovered in the 1860's) like gravitationally instable regions devoided of asteroids, with their side facing the outer planets being more devoided still. Jupiter and Saturn, on their way, disrupted any asteroids that were in orbit with them. Then, at 10 million years after the birth of the solar system, the gas and dust cloud dissipated as the Kuiper Belt forms, being less large than today as it contained 100 times comets more than now! Between 10 and 700 million years, the KB comets come and hit the gas giants, which those, Jupiter excepted, migrating outwards -albeit Neptune keeping coming before Uranus. Then, at 700 million years, it's the telluric planets which are in turn bombarded due to that the gas giants have orbits with larger eccentricites than today and sending the comets into the inner solar system. An opinion is that the early migration of the gas giants like described above would eventually have triggered the Heavy Bombardment Period, 3.9 billion years ago, and not the original chaos, asteroids being tossed out of the asteroid belt and having, naturally, the Earth, the Moon, or Mars for their targets. Such a migration also ejected small rocky bodies from the inner Solar System's Asteroid belt, to far-flung orbits at great distances from the Sun, resulting, for example, in that the Kuiper Belt likely contains a small fraction of rocky bodies from the inner Solar System, such as carbon-rich asteroids. From 730 to 800 million years after the solar system was born, it eventually reaches its current shape, with Neptune becoming the last planet of the system, the eccentricities of the gas giant decreasing to their values of today. A question posed by the study, at the light of the discovery of solar systems around the other stars, is why our system did not end like most of those found until now, that is a star, and, mostly, "hot Jupiters". Is the solar system a singularity? Or is that appearance due to that the tools of today don't allow to see such systems, akin to ours, around other stars? In terms of stability the solar system keeps evolving. Despite their small masses, the solar system's planets are influencing each other in terms of gravitation which, progressively, will make the system unstable. Orbit previsions beyond 100 million years may be theoretical only as, in about 1 billion years, it might that the Earth's orbit have become quite different
->More About the Early Solar System! Not long after Jupiter formed, it got pulled slowly toward the Sun, carried on currents of swirling gas which still existed at the time inside the protoplanetary disk. Saturn also got pulled in, and when the two giant planets came close enough to each other, their fates became linked. Their Sun-bound death spiral came however to a halt when Jupiter was about where Mars is now (and Mars not there yet) and the pair turned and moved away. That likely was due to that all the gas in-between both planets had been expelled through the closing. Saturn first stopped by 7 A.U. and then moved further to its current 9.5. Such a model of the early solar system is called 'Grand Track. Such a move, lasting hundreds of thousands to million years, profoundly influenced the solar system. Jupiter is thought to have formed in a region of space about three-and-a-half times as far from the Sun as Earth is or 3.5 astronomical units. As far as the influence of that unto the Asteroid Belt, which is believed to have formed as Jupiter's gravity prevented the rocky material there from coalescing and the zone remaining a loose collection of objects, the move of Jupiter downwards the Sun simply perturbed the area, pushed its objects farther away and switched places with it. And the same process occurred when Jupiter moved back outwards! That second episode further had Jupiter closing to the outer, Kuiper Belt, whence he sent icy bodies into the solar system. That might explain the long-standing mystery of why the Asteroid Belt is made up of both dry, rocky, and icy objects. The journey of Jupiter into the inner solar system may also help explain why Mars is so small, a unsolvable problem in the formation of the solar system. Mars is believed to have formed further out than Venus and the Earth did, having more raw materials to feed about and should have been larger. The passage of Jupiter might thus have scattered part of that material, beyond the 1 A.U. mark and leaving with slim feeding as Earth and Venus, on the other hand, kept forming in a region richest in planet-making material. Such a model, at last, could also show that Jupiter-like exoplanets mostly observed closer to their Sun than Mercury is to ours is not mere chance. The presence of Jupiter and Saturn closer to Sun also drove possible super-Earth planets close to our star on increasingly elliptical orbits, which finally would have doomed those. As Jupiter retreated into the solar system, it eventually left behind the mostly rocky remnants that later coalesced into Earth and earthlike inner planets. Jupiter generally, played a strong role in terms of balance, into the position of planets in the solar system
->Some More Discrepancies! Results by NASA's 2004 Genesis mission have discovered that our Sun and its planets seem to have formed differently as differences have been found in terms of oxygen and nitrogen, two of the most abundant elements in our solar system -with planets and asteroids with a lower concentration of the O-16 than does the Sun, or nitrogen in the Sun and Jupiter with slightly more N-14, but 40 percent less N-15 than elsewhere. Such findings show that all solar system objects including meteorites and comets are anomalous compared to the initial composition of the nebula from which the solar system, hence the Sun formed
->The International Astronomical Union (IAU) brought some important change into the solar system nomenclature. Taking act that 'contemporary observations are changing our understanding of planetary systems', the international body established three distinct categories for the planets and other bodies in the solar system: 'planets', which are celestial bodies orbiting the Sun and having a sufficient mass for self-gravity to have shaped them in an about spherical form, as, on the other hand, they have cleared their neighbourhood on their orbit; 'dwarf planets' are bodies orbiting the Sun, having a sufficient mass for self-gravity to have shaped them in an about spherical form too but which have not cleared their neighbourhood on their orbit, as, at last, they are not a satellite; 'small solar-system bodies", which are all other objects in the solar system (like comets, asteroids and the objects of the Kuiper Belt), orbiting the Sun, at the exception of the satellites. The IAU, further, dismissed Pluto from its status of planet. Pluto is now a 'dwarf planet' as, moreover, it's the prototype of a new category of 'trans-Neptunian', 'Pluto-class' objects. This leaves us with 8 'real' planets in the solar system only: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune
| Mercury Venus Mars Jupiter | Saturn Uranus Neptune Pluto |
MercuryMercury was named from the Roman fleet-footed messenger of Gods, due to that the planet was seen moving swiftly along either the eastern or western horizon, before sunrise or after sunset. The Greeks were naming Mercury like Hermes when it was a evening star, or Apollo when a morning star. Hence Mercury remained an ill-known, elusive planet until the space age. It was always low on the horizon, and badly observable. Mercury, on the other hand, is rotating one and a half time for one orbit around the Sun. The day, at Mercury, is lasting 176 Earth days! Mercury's night side cools to a few hundred degrees below zero while the dayside bakes at a toasty 800°. F. Mercury is very similar to our Earth's Moon and has a relatively similar history. Once the heavy bombardment period over (craters at Mercury are deemed about between 3.8, and 4 billion years ago), Mercury was flowed by lava which covered the old silicate crust. Then the inner layers of Mercury cooled down to the core. The crust cracked with large faults creating. Those so-called 'lobate scarps' are thrust faults, with the largest one more than 620 miles (1,000 km) in length. That cooling further is causing Mercury to shrink with a similar process at our Moon causing our satellite to shrink by some 300 ft (100 m) each billion year. The shrinking is larger than that at Mercury as the planet may be considered a 'giant iron planet with a thin rock crust', the larger the iron core, the greater the shrinkage. The shrinkage might have lasted a long swath of time. Volatiles can swiftly switch states underneath Mercury's surface triggering quakes at the origin of the planet's chaotic terrain. Some more lava floods occurred at some parts of Mercury, as the bombardment of micrometeorites eventually produced a dusty surface, made of a material called regolith. Some more large impactors created some more craters. Impact features at Mercury range from so-called 'ghost craters' through medium-sized basins such as Mozart, or to the largest basins on Mercury, including Rembrandt and the mighty Caloris. The Caloris basin is likely a reminder of a powerful asteroid event. Many of impact craters -the large basins included- at Mercury have been flooded by lavas as such areas further may host tectonic structures like graben, ridges and scarps that formed during or after volcanic infilling. As Mercury obviously lacks a 'sea level,' the zero-point reference elevation there is defined to be the mean planetary radius of 1,516 miles (2,440 km). Mercury has no atmosphere (Mercury atmosphere elements are due to meteorides yielded by comet Encke, featuring the shortest period of any comet, returning to perihelion every 3.3 years at a distance of 31 million miles (nearly 50 million kilometers)), as it has a magnetic field and a magnetosphere. The magnetic field might be due to a magneto molten core, like at Earth, or it might be the remnant of a former strong magnetic activity. Mercury's magnetosphere is tilted 7° relative to the planet's axis
The space age allowed to a better knowledge of Mercury. Mercury was explored from orbit by the Mariner 10 spacecraft in 1974-1975 as NASA's mission Messenger is currently renewing study of the planet since 2009. The mission discovered that the Mercurian surface is poor in iron, but rich in moderately volatile elements such as sulfur and sodium definitively explaining Mercury’s anomalously high density compared with the other planets in the inner solar system. Interior is highly chemically heterogeneous, providing important clues to the early geological history of the planet. The surface of Mercury was shaped by volcanic activity as some unique landforms shaped by loss of volatile materials. Like at Moon, presence of large amounts of water ice protected from the Sun’s heat within permanently shadowed impact craters near the planet’s poles was found. Most of the water on Mercury was delivered by impacting asteroids, and also by the solar wind's charged particles producing hydroxyl groups when colliding the planet's minerals. The complex interplay of the interplanetary magnetic field with that of Mercury results in a remarkably dynamic electromagnetic environment surrounding the planet, including unexplained bursts of electrons and highly variable distributions of different elements in the thin exosphere. Mercury is trailing behind it a sodium-rich exospheric tail extending more than 25,000 miles (40,000km) from the planet as a first passage of the MESSENGER mission to the planet in 2008 revealed a hydrogen tail of similar dimensions. A recurring meteor shower, possibly associated with comet Encke that also produces some minor meteor showers on Earth is also concerning Mercury, which is a giant dust collector
check more data about Mercury, from the MESSENGER mission (2011-2015)
VenusVenus was ill-known until space exploration began, as its surface was hidden to observation by a dense cloud cover and as the planet, like Mercury, was an evening or morning star. Babylonians noted its wanderings in texts as far back as 1600 BC as the Greek mathematician Pythagoras sweated out the orbits of Venus, eventually becoming the first to determine that what had been believed to be unique and separate evening and morning stars as believed by the ancient Egyptians and Greeks, was actually just one object, Venus. The discovery that Venus had an atmosphere was done in the 18th century A.D. by Russian astronomer Lomonosov in St. Petersburg during a transit. In the 1940's and 50's, a lot of scifi classics by Isaac Asimov and others saw Venus like a oceanic world, with Earth explorers using submarines to explore. U.S. Mariner 2 spacecraft was the first to fly past Venus on Dec. 14, 1962. Venus size, mass, density, and volume are similar to the ones of Earth. Its atmosphere is mainly composed of carbon dioxide however, as sulfuric acid rains are falling from its clouds, which lie at a towering 14 miles (23 km) high! That combination of greenhouse gas and perennial cloud layer led to an enormous greenhouse warming. The surface environment at Venus is dimly lit. Recent studies by an European mission to Venus have shown that lightnings in the atmosphere may trigger the formation of molecules. Venus, along with Jupiter, Saturn and the Earth thus is a planet where lightnings occur. Although winds on the planet’s surface move very slowly, at a few mph, the atmospheric density at this altitude is so great that they exert greater force than much faster winds would on Earth. The surface atmospheric pressure is 92 times Earth's and the temperature is about 900° F (482° C) on both the day and night sides. The atmosphere of Venus endured a runaway greenhouse effect as the Sun's radiation was trapped by the cloud cover in a cumulative way. 95 percent of Venus' atmosphere is carbon dioxyde as the sulfuric acid rain is vaporizing before reaching surface The warmth at Venus results from that it endured volcanism which ejected sulfur in the atmosphere at the water of it evaporated charging the atmosphere with water vapor. That turned into a greenhouse effect which accelerated and kept the process going. Twice as much hydrogen as oxygen escaping from the atmosphere of Venus might hint to that there could have been large amounts of water likely locked in the atmosphere at the very beginnings of the planet's history when the surface still was molted. The main culprit in the greehouse process might have been ancient oceans which the Sun's heat turned into water vapor, a greenhouse gas. Billions of years ago, Venus might have featured the first solar system's ocean as Venus lost its oceans albeit formed from the same components as Earth. Gravity waves generated at the surface of either the warmed equator or at large mountains, are bringing the water vapour found beneath Venus' cloud layer to just beneath the top of it. Venus' day is 243 days long and the planet is orbiting the Sun in 225 days. It's likely that the planet's axis of rotation is nearly upside down, giving Venus an apparent retrograde rotation, that is that Venus is rotating clockwise, or another explanation might be that the backwards rotation had to do with large impacts during the planet was still forming. Until recently, it was assumed that a thick atmosphere like that of modern Venus was required for the planet to have today’s slow rotation rate, which is not true. The planet's cloud cover is "super-rotating" that is that the clouds are rotating faster than the surface below them. Venus’ cloud tops rotate with a period of four days only, a observation made by NASA's Mariner 10 mission which confirmed those made from the Earth. Four temperature inversions occur higher in the atmosphere likely caused by cloud formations as Venus is 100 times closer to being a perfect sphere than the Earth, and temperatures at Venus’ cloudtops are the same on both the day and night sides. Venus has a volcanic activity, which is is shaping, and resurfacing the landscape. Most of that activity occurred in the past in titanic explosions similar to -but much larger than- what happened with the Deccan Traps, or supervolcanoes, on Earth. The surface of Venus is almost completely covered, one way or another, with volcanic features like broad and flat basalt plains as Hawaiian-style shield volcanoes are another feature. Flow-type Venus plateau was more basalt than granite as the early Venus had plate tectonics and the planet was in the habitable zone due to Sun dimmer at the time. Venusian relief features are believed to have been last resurfaced 300 to 500 million years ago albeit some volcanic activity is occurring nowadays. Venus was mainly explored by the Magellan spacecraft at the beginning of the 1990s. Craft from the former USSR managed to land on the surface between 1975 and 1981. Data from the ESA Venus Express in 2010 have been overlaid on topographic data from the Magellan mission and identifying relatively young lava flows hinting to some volcanic activity between a few hundred years to 2.5 million years ago. Scientists previously had detected plumes of hot rising material deep under Venus' surface thought to have produced significant volcanic eruptions as other data from the planet suggest that volatile gases commonly spewed from volcanoes were breaking down in its atmosphere. The Venus Express results suggest a gradual sequence of smaller volcanic eruptions as opposed to a cataclysmic volcanic episode that resurfaces the entire planet with lava as the study might hint too to that Venus is still active today. A sharp rise in the sulphur dioxide content of the upper atmosphere in 2006–2007 or thermal events spotted at the surface in tectonic rift areas might hint to active volcanism on Venus nowadays. Venus's crust is thicker that Earth's as the planet does not feature any plate tectonics. Some Venusian regions are dome-shaped and a diameter about 20 miles (30 km) as they are the equivalent of 'laccoliths' on Earth, areas where subjacent magma is surging upwards. As the eight Russian landers of the 1970s and 1980s touched down away from the highlands and found only basalt-like rock, granite was found on the Phoebe and Alpha Regio plateaus, a hint to a possible plate tectonics, a ocean and volcanism. Highland plateaus of Venus might be ancient continents, once surrounded by ocean that might have evaporated away into space and produced by past volcanic activity. Some volcanic activity might still be extant nowadays as lava flows might have been created no more than 2.5 million years ago. Scientists also debate whether past or present volcanic activity is the source of the sulfur dioxide clogging Venus' atmosphere. Venus may have had a shallow liquid-water ocean and habitable surface temperatures for up to 2 billion years of its early history as with more land than at the Earth and clouds shielding from sunlight -- even with a ancient Sun up to 30 percent dimmer than nowadays, ancient Venus still received about 40 percent more sunlight than Earth does today -- the planet might have be prone to life. Venus might have been habitable until as recently as 700 million years ago. That was put to a end by a near-surface resurfacing event, of the type of what happened on Earth at the Siberian Traps, 500 millions years ago, but on a much larger scale. A Pioneer mission to Venus in the 1980s first suggested Venus originally may have had an ocean. However, Venus is closer to the Sun than Earth and receives far more sunlight. As a result, the planet’s early ocean evaporated, water-vapor molecules were broken apart by ultraviolet radiation, and hydrogen escaped to space. With no water left on the surface, carbon dioxide built up in the atmosphere, leading to a runaway greenhouse effect that created present conditions
Venus' white clouds, which makes the planet's atmosphere about 100 times thicker than Earth's, along with other molecules in the atmosphere reflect more than 80 percent of the Sun's light back out into space as they lie at a altitude of 37 miles. Yet when the Russian probe Venera 4 landed on the Venusian surface in 1967, it measured a temperature of 900 degrees Fahrenheit (482 degrees Celsius) which is hot enough to melt lead. Carbon dioxide comes with the clouds trapping heat on the planet's surface. The little heat from the Sun that makes it through the reflective cloud barrier has little chance of escape, leading to a intense greenhouse effect. Such a greenhouse effect was triggered by the intense volcanism at Venus as too few water forbade any evacuation of the CO2 in that atmosphere. Such a heating -of the clouds included- can also explain Venus extreme air circulation up to hurricane-force winds, causing the atmosphere at cloud level to circulate 60 times faster than the planet rotates, what is called a 'super-rotation.' The whole atmosphere circles the planet in just four Earth days, much faster than the planet's spin period of 243 days. Higher-altitude winds at the 40-mile high cloud-tops whizz around at up to 306 mph, some 60 times faster than the rotation of the planet itself. The dynamics of super-rotation are still a puzzle however. Winds are dragging thick layers of cloud with them as they go. Super-rotation appears to behave more chaotically on the night side as night-side clouds also create different patterns and shapes than those found elsewhere –- large, wavy, patchy irregular and filament-like patterns –- and are dominated by mysterious 'stationary waves.' These waves appear to be concentrated above steep and higher-altitude regions of the surface. Polar vortices form both North and South because heated air from equatorial latitudes rises and spirals towards the poles, carried by the fast winds. As the air converges on the pole and then sinks, it creates a vortex. The southern vortex is a turbulent mix of warming and cooling gases, all surrounded by a area of cool air. The vortex rotates with a period of around 44 hours. The polar vortices of Venus are among the most variable in the solar system. By 2011 Venus was found by a ESA mission to harbour a ozone layer at a altitude of 62 miles (100 km), as the ozone forms when sunlight breaks carbon dioxide molecules, releasing oxygen atoms with are swept then into the nightside where it sometimes recombine into three-oxygen atoms ozone molecules. Strange stripes in the upper clouds of Venus are called 'blue, or UV absorbers' because they absorb blue and ultraviolet wavelengths of light and likely play a key role into absorbing heat into the planet's atmosphere.. One explanation is that convective processes dredge the absorber from deep within Venus’ thick cloud cover and the material in dispersed the direction of the wind into the sole dark areas, creating the long streaks. The atmosphere of Venus seems to be more variable than previously thought as far as its upper layers are concerned. Scientists also know that the nightside Venus atmosphere produces a glow, called the 'Ashen light.' That process is still ill-known as it might be due to lightning on Venus
As far as Venus lightning phenomenon is concerned, recentest data are showing that lightning at Venus are similar in process to the ones seen at Earth, depiste the difference in atmospheric conditions. Thunderbolts thus are triggered in sulphuric clouds as until now one thought that Venusian clouds mostly were of the fog species and not conducive to lightning. The Sun at Venus might be the originator, with energy then powerfully released. Lightning at Venus is more prevalent on the planet's dayside than at night, and occurs more often at low latitudes, where the solar input to the atmosphere is strongest. Lightning usually are caused when cloud particles collide in the atmosphere and electrical charges are transferred from the larger ones to the small. Large particles fall while the small ones are carried upward and that separation of charges leads to lightning strikes
MarsMars is the famous Red Planet. Its red color, which is yielded by the oxydisation mechanisms at the surface of Mars, brought to its name taken from the Roman god of war. It was thoroughly observed by diverse crafts and probes, from orbit or from the surface, like Mariner 4 in 1965, the Viking landers or more recent missions. Mars is a rocky world with craters, ancient volcanoes, large plains, and a famous canyons' system, Vallis Marineris. The Red Planet, further, is characterized by a strong difference between its both hemisphers. The northern one is hundreds of yards lower than the southern one, as that might have bee caused by a gigantic impactor, 3.9 billion years ago, which would have created that huge crater of sort, North (and, further, disrupted Mars' global magnetic field) as an alternate explanation is that the difference might have originated into super lava flows in the North of Mars. Mars' crust is thicker that Earth's as the planet does not feature any plate tectonics. Mars' famous polar caps are alternately freezing and vaporizing along the seasons. The average temperature at Mars is - 81° F (- 63° C), as the pressure is low. Mars has a thin atmosphere which is composed of carbon dioxide. Mars was always considered the best match for a life-hospitable place in the solar system. Percival Lowell, at the end of the 19th century, thought Mars had a channels' net linked to living creatures. The life question was scientifically investigated by the Viking landers about 1976, and the answer was mostly negative. The question of life at Mars is always pending and still agressively searched, as it's now related to the presence of water. Two small moons are orbiting around Mars: Phobos and Deimos
JupiterJupiter is the solar system's largest planet, and the first of the gas giants. Scientists estimate that if Jupiter had been at least 80 times more massive at its formation, it could have turned a red dwarf star rather than a planet. Latest space missions, like Juno, by 2017 have shown that the largest planet in our solar system is a turbulent world, with an intriguingly complex interior structure, energetic polar aurora, and huge polar cyclones. Such large, gazeous planets are located beyond Mars and the asteroid belt, and they are mainly made of gas which accreted around a very small solid core as a large layer at Jupiter is composed with liquid metallic hydrogen. The gas is organized in layers, the nearer the core, the denser. Gas giants have their deep atmosphere layered with multiple cloud decks. Giant planets take billions of years to cool down after they are formed. Consequently, there is as much heat coming out of Jupiter's interior as is received by the planet from the Sun. This heat is carried by convection currents, which stir the interior and produce the swirling clouds and storms. Cyclonic vortices at Jupiter might be internal energy smokestacks, helping release internal energy through convection as lightnings are a marker of that convection. Jupiter's poles are heating the planet's atmosphere due to auroras, to a greater depth than previously thought, into the upper atmosphere, or stratosphere. A series of jet streams slice across the externalmost layer and also at other altitudes. The high above Jupiter’s equator, east–west jet stream is reversing course on a regular schedule. Similar equatorial jet streams have been identified on Saturn or on Earth. Jupiter’s cycle is called the quasi-quadrennial oscillation, or QQO, and it lasts about four Earth years. Saturn has its own version of the phenomenon, the quasi-periodic oscillation, with a duration of about 15 Earth years. The equatorial jet extends quite high into Jupiter’s stratosphere as gravity waves are the primary driver, resulting from convection in the lower atmosphere and travelling up into the stratosphere, where they force the QQO to change direction. A gas giant features a troposphere, a high layer of the atmosphere. Swirls, bands and spots are the marks of weather events in the layers' upper part. Solar waves may impact gas giants. Jupiter's clouds are arranged into bands of different latitudes, known as 'tropical regions.' These bands are parallel to the equator and they are produced by air flowing in different directions at various latitudes. Jupiter fast rotation creates strong jet streams, separating its clouds into those dark belts and bright zones. Those alternating wind motions are are created by differences in the thickness and height of the ammonia ice clouds. Lighter colored areas, called 'zones,' are high-pressure where the atmosphere rises and the clouds thicker, as darker low-pressure regions are where air falls and called belts. Bands are are separated by winds that can reach speeds of up to 400 miles (644 kilometers) per hour. 'Deep atmospheric winds' extend from the planet's surface to over 1,860 miles (3,000 kilometers) deep, where the planet's interior begins changing from gas to highly conductive liquid metal. Bands of flowing atmosphere actually penetrate deep into the planet, to a depth of about 1,900 miles (3,000 kilometers). Brown barges are cyclonic regions that usually lie within Jupiter's dark North Equatorial Belt, although they are sometimes found in the similarly dark South Equatorial Belt as well. They can often be difficult to detect visually because their color blends in with the dark surroundings. At other times, as with this image, the dark belt material recedes, creating a lighter-colored background against which the brown barge is more conspicuous. Brown barges usually dissipate after the entire cloud belt undergoes an upheaval and reorganizes itself. Atmospheric wave trains, towering atmospheric structures, trail one after the other as they roam the planet, with most concentrated near Jupiter's equator. Distance between crests varies from 40 miles (65 kilometers) to 760 miles (1,200 kilometers) with a height about 6 miles (10 kilometers). Wave trains are oriented East-West. Most such waves are expected to be atmospheric gravity waves – up-and-down ripples that form in the atmosphere above something that disturbs air flow, such as a thunderstorm updraft, disruptions of flow around other features, or from some other disturbance. Gas giants generally feature two types of molecular hydrogen differentiated by whether their protons have aligned ('para') or opposite spins ('ortho'). The fraction of hydrogen in the para flavor is a good indicator for gasses upwelling from deep within the planet’s atmosphere. The Great Red Spot indicates a upwelling of gas that is cooling the atmosphere as the belt zone structure near the equator shows that the equator is cold and surrounded by warm belts of sinking gas. The Earth could easily sits inside the Great Red Spot. Jupiter's Great Red Spot clouds race counterclockwise around the oval's perimeter with wind speeds greater than any storm on Earth. The Great Red Spot has diminished in width by one-third and height by one-eighth since ancient observation. The atmospheric heating from Jovian aurora in the northern reaches of the planet indicates the presence of methane and ethane in the stratosphere. There is a gradual trend concerning the up or downwelling from the equatorial to polar regions. Large storms on Jupiter evolve over decades. One of these spots, the Great Red Spot, is a anticyclonic hurricane which had been born three centuries ago. The European ESO, along with the Gemini and the Subaru, telescopes provided in 2010 for unprecedented views of the Great Red Spot. Such views are showing that the the reddest color of the Great Red Spot corresponds to a warm core within the otherwise cold storm system, and images show dark lanes at the edge of the storm where gases are descending into the deeper regions of the planet. The Great Red Spot used until now to be seen like a plain old oval without much structure as it is, in fact, extremely complicated. Continuous observations of the current shape of the sport are dating back to the 19th century. The spot is a cold region averaging about 110 Kelvin (minus 260 degrees Fahrenheit; minus 160 degrees Celsius) with winds peaking at about 400 miles an hour. The extremely high temperatures observed above Jupiter's Red Spot might hint to a energy transfer due to energy and acoustic waves colliding and heating up the upper atmosphere. The most intense orange-red central part of the spot is about 3 to 4 Kelvin (5 to 7 degrees Fahrenheit) warmer than the environment around it. This temperature differential is enough to allow the storm circulation, usually counter-clockwise, to shift to a weak clockwise circulation in the very middle of the storm. Not only that, but on other parts of Jupiter, the temperature change is enough to alter wind velocities and affect cloud patterns in the belts and zones. There is a intimate link between environmental conditions -temperature, winds, pressure and composition- and the actual color of the Great Red Spot as scientists do not know for sure which chemicals or processes are causing that deep red color. Color of Jupiter's Great Red Spot is likely a product of simple chemicals being broken apart by sunlight in the planet's upper atmosphere as most of the Great Red Spot is bland in beneath the upper cloud layer of reddish material. The spot's great heights both enable and enhance the reddening. The Great Red Spot also cuts off the atmosphere in its core from the surrounding environment as it is embedded deep down in the turbulent 'weather zone.' NASA Juno mission by late 2017, showed that Jupiter's Great Red Spot has roots penetrate about 200 miles (300 kilometers) into the planet's atmosphere as clouds are warmer at the base than they are at the top, yielding those ferocious winds observed at the top. A liquid ocean of hydrogen surrounds Jupiter' core, and the atmosphere consists mostly of hydrogen and helium. That translates into no solid ground like we have on Earth to weaken storms. Jupiter’s upper atmosphere has clouds consisting of ammonia, ammonium hydrosulfide, and water. Still, scientists don’t know exactly how or even whether these chemicals react to give colors like those in the Great Red Spot. The Little Red Spot is the third largest anticyclonic reddish oval on the planet, which has been tracked for the last 23 years. A large, transient storm called the South Equatorial Disturbance is also blowing in the southern hemisphere of Jupiter since 1999, and called 'Red Spot Jr.' Unlike to the large 2011-12 storm at Saturn, Jupiter's storms have a quiet center, and not the violence at the center of Saturn's storms. Storms at Jupiter can last as little as a few hours or stretch on for centuries like the Great Red Spot. Jovian storms in the planet's northern hemisphere are rotating counter-clockwise with a wide range of cloud altitudes. Darker clouds are expected to be deeper in the atmosphere than the brightest as the latter might be updrafts of ammonia ice crystals possibly mixed with water ice. NASA's Juno mission results estimated that at the equator, water makes up about 0.25 percent of the molecules in Jupiter's atmosphere only. Cloudless patches in the weather of Jupiter are so exceptional that the big ones get the special name 'hot spots,' which reside in Jupiter's jet streams. They have a geometrical shape and they are due to a Rossby wave, a pattern also seen in Earth's atmosphere and oceans, which results from a blast of air. On Jupiter is then glides up and down in altitude around the planet (and not in latitude, like at Earth). Complex winds blow around and through those spots. Because hot spots are breaks in the clouds, they provide windows into a normally unseen layer of Jupiter's atmosphere, possibly all the way down to the level where water clouds can form. In pictures, hot spots appear shadowy, but because the deeper layers are warmer, hot spots are very bright at the infrared wavelengths where heat is sensed.Typically, eight to 10 hot spots line up, roughly evenly spaced, with dense white plumes of cloud in between as the wave pushes cold air down, breaking up any clouds, and then carries warm air up, causing the heavy cloud cover seen in the plumes. Wind gyres, or spiraling vortices, merge with the hot spots. The Rossby wave may rise and fall 15 to 30 miles (24 to 50 kilometers) in altitude. Lightnings have been seen occurring by the gas giant's poles. Lightnings at Jupiter had been first spotted by the Voyager spacecraft as the Juno mission found that they were analogous to those at Earth, as they are mostly found at Jupiter's poles on the other hand. Scientists believe that is the heating at Jupiter's equator from the Sun, that creates stability in the upper atmosphere, inhibiting the rise of warm air from within as the poles do not have this upper-level warmth and are most instable, allowing warm gases from the planet's interior and driving convection. Lightnings are likely fueled too my moisture. Cyclones swirl around the south pole, and anticyclonic white oval storms can be also seen. Altitude on Jupiter is measured in bars, which represent atmospheric pressure, since the planet does not have a surface, like Earth, from which to measure elevation. High bands of haze exist at Jupiter's north pole
The space exploration helped learn more about Jupiter. From Pioneers' findings, scientists were able to make numerous conclusions about Jupiter. They found that the planet is composed mostly of liquid, and that it had a magnetotail, like Earth. This hinted at Jupiter’s composition and the possibility of a solid core. They also got a close look at Jupiter’s clouds – from 26,000 miles (42,000 km) – to determine weather patterns. The Voyager pair flew past Jupiter in 1979, taking more than 52,000 photos of the planet and its moons over the course of several months. The data revealed many features of the weather on Jupiter, including the existence of lightning in the cloud tops and of hurricane-like storm systems as for the first time, scientists also discovered the existence of active volcanoes at Jupiter's moon Io, elsewhere than Earth. The atmospheric probe of mission Galileo, in late 1995, passed 58 minutes of atmospheric data to its orbiter, which then transmitted it back to Earth. New Horizons also, a mission to Pluto, added to observations of Jupiter, during its flyby there in 2007, finding the planet changed since previous looks by NASA. Most notably, New Horizons saw about 36 volcanoes on Io and measured the temperature of lava, finding it similar to that of Earth-based volcanoes. The New Horizons mission also saw clouds forming from ammonia welling up from the lower atmosphere and heat-induced lighting strikes in the polar regions, demonstrating that heat moves through water clouds at virtually all latitudes across Jupiter. 'Waves' that run the width of planet are indicating violent storm activity below. The rings also were observed in details, with clumps of debris that may indicate a recent impact inside the rings, or some more exotic phenomenon. The lesser Metis and Adrastea moons are shepherding the materials around the rings. A major eruption was at that time in progress at the northern volcano Tvashtar on Io, with the plume condensing at high altitude and falling back to the moon’s surface, confirming, generally Io like the solar system’s most active body and with a atmosphere, showing more than 20 geological changes since the Galileo Jupiter orbiter provided the last close-up look in 2001. Tons of Io material also flow into the Jovian magnetotail as large, dense, slow-moving blobs. In October 2015, the Hubble Space Telescope took photos which showed changes in Jupiter’s Great Red Spot, and in June 2016, Hubble took awe-inspiring photos of auroras on the planet’s poles. First revelations by NASA's Juno mission by early 2017 are showing that Jupiter's magnetic fields and aurora are bigger and more powerful than originally thought and that the belts and zones extend deep into the planet’s interior
Jupiter has a large satellite system, with four, large, well-known satellites. These are called the "Galilean satellites" because they were discovered by Galileo Galilei, the first astronomer to use a telescope ever in the 17th century. Jupiter's moons might have formed from a circumplanetary disk surrounding the gas giant. Diminutive Amalthea in 1892 was the last satellite in the solar system found by visual observation -- all subsequent discoveries occurred via photography or digital imaging. Jupiter has the most powerful magnetosphere in the solar system. It's acting like a powerful radio beacon, as its tail probably extends until the orbit of Saturn! Jupiter was explored by the Pioneer and Voyager missions, and, lately, by the Galileo spacecraft which spent some years in orbit around Jupiter, providing a thorougful study of the Jovian system. Jupiter's magnetic field does a connection between the moons and Jupiter and material from some of the moons, Io in particular, is being lofted into space. First missions found that Jupiter had a faint ring system. The shadow of Jupiter is a factor about the rings of the planet. Like the three other giant planets in the solar system, Jupiter formed early after the Sun had formed. Like Saturn or Uranus, Jupiter emits more energy that it receives from the Sun, as this is due to, with is mass, the giant planet would have needed 6 billion years to cool compared to the 4.5 billion years or the solar system. Jupiter radiates 2 to 2.5 times more heat than it receives from the Sun which hints to a internal heating, a fact discovered by the Pioneer 10 mission who had made the first infrared observations of the planet’s night side
check more data about Jupiter, from the Galileo mission (1995-2003)
SaturnSaturn is the solar system's second-largest planet, after Jupiter. It's very similar to the latter. Saturn is a gas giant, with gas in layers around a small, solid inner core. Saturn's upper layers are made of liquid molecular hydrogen. The most distinctive trait of Saturn is obviously its famed ring which is a fine show to any amateur astronomer. Saturn's rings, like at Uranus and Neptune, with the planet's moons, form an intricate interrelated system. On the day side, Saturn's rings are illuminated both by direct sunlight, and by light reflected off Saturn's cloud tops. Saturn's ring is thought to have originated from collisions between the planet's moons or from a foreign body which was disrupted by the planet's gravitational field. The ring, in no place, is thicker than a 2-story building, as it's composed of billions of individual, icy or rocky particles, each one orbiting the planet on its own path. Saturn ring system is spanning 4,350-49,700 miles (7000 to 80000 km) above the planet’s equator and mostly composed of particles of water ice contaminated with traces of rocky material. Such particles are variable in size, lacing dust grains to mountain-sized chunks. The ring, generally, is alternating bright, dense clumps and darker, sparser patches with some real key breaks like the Cassini Division for example, and rings gaps cleared by ring moons or orbital resonances. The weather activity is not as pronounced at Saturn than the one which is seen at Jupiter. Neighboring bands of clouds move at different speeds and directions depending on their latitudes, which generates turbulence where bands meet and yields a wavy structure along the interfaces. Saturn’s upper atmosphere constitute a faint haze. Saturn’s colors come from hydrocarbon hazes above the ammonia crystals in the upper cloud layers. Unseen lower-level clouds are either ammonium hydrosulfide or water. Winds are reaching much stronger speeds however as they may abruptly change in direction. Saturn's winds race furiously around the planet, blowing at speeds of more than 1,100 miles per hour (1,800 kilometers per hour) -- some of the fastest in the solar system. It is those winds and clouds which yield, due to their varied altitudes, the distinct bands and zones which encircle the planet's pole, as well as its famous hexagon, North, which is due to a meandering polar jet stream. These zonal winds spin off swirls and eddies, which are significant storms in their own right. During a summer for a given Saturnian hemisphere, the atmosphere is more active. A major storm, the 'Great White Spot' was seen by the Hubble Space Telescope in November 1990, a disturbance of 200,000 mile-long and 6,000-mile wide. A serene upper atmosphere at Saturn is constituted by the planet's stratosphere as it is divided from the lower churning atmosphere by a 62-mile high tropopause. Major ammonia icy storms at Saturn are seen in a band of latitude called the 'storm alley,' where disturbances may consist into a cluster of thunderstorms. Such Saturnian storms are hinted to by larger than expected amounts of phosphine, a gas typically found in Saturn's deep which is lifted up into the upper atmosphere from 62 to 124 miles, where lightnings are occurring and clouds are made of ammonia and water. Storms at Saturn might occur at a height of about 62 miles (100 kilometers) down from the bottom of Saturn's calm stratosphere and feel like intense ammonia-ice blizzards, powered by violent storms deeper down - perhaps another 62 to 120 miles (100 to 200 kilometers) down - where lightning has been observed and the clouds are made of water and ammonia. Huge storms called Great White Spots usually are appearing during late northern summer. A giant early-spring storm has been raging at Saturn' northern hemisphere since December 2010 as it completely circled the planet as soon as in late January 2011 as it affected the clouds, temperatures and composition of the atmosphere for more than three years. That storm is the 6th one only to be recorded since 1876 as the last one had occurred in 1990 and then by 2009 in an area known as 'Storm Alley' in the southern hemisphere, but it was about 100 times smaller in area and lasting 334 days. The disturbances yielded in 2011 look like the largest observed ever. That storm was the largest and longest during last both decades, with a North-South 9,000-mile width and a duration of 200 day. The previous duration record holder was a storm in 1903 at 150 days. As it rapidly expanded, its core developed into a giant, powerful convective thunderstorm, yielding a 3,000-mile-wide (5,000-km) dark vortex, possibly similar to Jupiter's Great Red Spot and generating disturbances in the otherwise stable Saturnian stratosphere. The atmospheric winds had been modified, with jet streams and giant vortices disrupting Saturn's slow seasonal evolution. Such storms originate deep in Saturn's atmosphere as they punched through the planet's serene cloud cover to roil the stratosphere then. In the Saturnian atmosphere, the amounts of acetylene and phosphine are both considered to be tracers of atmospheric motion. Storm lightnings comes from the water clouds, where falling rain and hail generate electricity. The mystery is why Saturn stores energy for decades and releases it all at once as such outbursts are episodic and keep happening on Saturn every 20 to 30 years or so. This behavior is unlike that at Jupiter which have numerous storms going on at all times. That event was the last outbreak of a mysterious great white spot erupting in the planet's atmosphere every Saturn year -29.5 Earth's years. Such periodic superstorms might arise from water, which is heavier than Saturn's dominant gases, hydrogen and helium. The water passing to the lower atmosphere makes it turn denser that what is above. But the upper atmosphere gradually cools by radiating warmth into space and eventually gets so cold that it becomes denser than the air below, unleashing warm moist air upwards and trigger a rash of those enormous thunderstorms. Albeit the convective phase of the storm ended by late June 2011, and a duration of 200 days, turbulent clouds were still lingering in the atmosphere by late 2011. The storm first appeared at approximately 35 degrees north latitude on Saturn and eventually wrapped itself around the entire planet to cover approximately 2 billion square miles (5 billion square kilometers). The forceful storm generated unprecedented spikes in temperature and increased amounts of ethylene and acetylene. Waves of energy rippled hundreds of miles (kilometers) upwards, depositing their energy as two vast swirls of hot air in the stratosphere which eventually merged to create an enormous vortex. That giant storm occurred during northern hemisphere spring, years ahead of the predictably stormy summer season. That 2011-12 Saturnian storm behaved like a terrestrial hurricane but with a twist unique to Saturn as it consumed itself when meeting its own trail, which is not seen, for example, at Jupiter. Like hurricanes at Earth, it fed off from warmth. The bright, turbulent head of the storm emerged and started moving west, spawning a clockwise-spinning vortex that drifted much more slowly. It eventually ran into its own wakes as no obstacle was there to dissipate it, like what occurs on Earth. It was only when the head of the storm ran into the vortex in June 2011 that the massive, convective storm faded away. How that unfolded precisely is still a mystery. Some lingering effects kept in higher layers of Saturn's atmosphere. The storms's updraft erupted with an intensity that would have wipped out the entire volume of Earth's atmosphere in 150 days, also creating the largest vortex ever observed in the troposphere of Saturn, expanding up to 7,500 miles (12,000 kilometers) across. This storm was the longest running of the massive storms that appear to break out in Saturn's northern hemisphere once every 30 Earth years. Saturn was explored by the Voyager 1 and 2 missions, as the most recent Cassini mission will spend four years in orbit studying the Saturnian system and Titan, Saturn's main moon. Saturn, like Jupiter, has a vast system of satellites. The ringed planet takes 29 years to complete its orbit. Saturn's atmosphere is affected by a wave oscillation on a pattern of 15 years (each Saturn's half year) either side of the equator, with the changes in temperature layers bringing the winds keeping changing direction and generating that oscillation. Such phenomenons exist too at Jupiter and the Earth. Charged water particles flow into the Saturnian atmosphere from the planet's rings, causing a reduction in atmospheric brightness as such a rain influences the composition and temperature structure of parts of Saturn's upper atmosphere, or ionosphere hence the weather. That rain is severely reducing the electron densities where it falls. Saturn litterally is banded in terms of a specific ion -the triatomic hydrogen- with lighter bands corresponding to the gap in the rings and darker one to the rings hence the ring's rain. Rain particles are drawn towards Saturn through the planet's magnetic field lines. Like Jupiter, Saturn is re-emitting more energy than the one it receives from the Sun. In the case of Saturn this is due to the heavier helium percolating down through hydrogen and this motion towards the center of the planet generating heath
As far as the historical discovery of the rings of Saturn is concerned, Italian astronomer Galileo was the first to look at Saturn through a telescope in 1609 and 1610 as the view of Saturn was a puzzling sight. Unable to make out the rings, he thought what he saw were two sizable companions close to the planet, writing that '[T]o my very great amazement, Saturn was seen to me to be not a single star, but three together, which almost touch each other,' or he referred to the peculiar shapes surrounding the planet as 'Saturn’s children.' 2 years later, he was more amazed still as the two bodies seemed to have disappeared. 'I do not know what to say in a case so surprising, so unlooked for and so novel' The rings then had simply turned edge-on! When 2 years later they had reappeared and looked larger, Galileo concluded that what he saw were some sort of 'arms' that grew and disappeared for unknown reasons. It was not before nearly half a century later that the Dutch scientist Christiaan Huygens found the answer. Thanks to better optics, Huygens was able to pronounce in 1659 that the companions or arms decorating Saturn were in fact a set of rings. These were named in the order in which they were discovered, using the first seven letters of the alphabet: the D-ring is closest to the planet, followed by C, B, A, F, G and E. Saturn's rings system has a very small height compared to its size. The mainly water ice ring should be 4.4 billion, or 200 million years old as a surprisingly small amount of dusty, micrometeoroidal material comes into contact with the rings at 10-19 g of dust per square centimeter per second. Huygens also discovered the moon Titan. A few years later, the Italian-French astronomer Jean-Dominique Cassini added several other key Saturn discoveries while using new telescopes. He discovered Saturn’s four other major moons – Iapetus, Rhea, Tethys and Dione as in 1675, he discovered that Saturn’s rings are split largely into two parts by a narrow gap, known since as the 'Cassini Division.' In the 19th century eventually, James E. Keeler, pursuing theoretical studies by James Clerk Maxwell, showed that the ring system was not a uniform sheet but made up of small particles that orbit Saturn. 4 moons of Saturn and a large gap in Saturn's ring system which is now known as the Cassini division, were discovered by French-Italian astronoer Giovanni Domenico Cassini (1625-1712)
->Compositional Difference Between the Ice Giants and the Gas Giants
 | Compositional difference between the ice giants and the gas giants. site 'Amateur Astronomy' based upon a picture NASA |
UranusScientists determined that the atmosphere of Uranus is 85 percent hydrogen and 15 percent helium. There was also evidence of a boiling ocean about 500 miles (800 kilometers) below the cloud tops. Uranus revealed itself to be the coldest planet known in our solar system, even though not the farthest from the Sun. That is because it has no internal heat source. Uranus was discovered in 1781 only by English astronomer William Herschel and his sister Caroline. Herschel first had noted Uranus, in constellation Taurus, the Bull, like a star of a nebulous apparence. He defined it then like a comet and, eventually, like a planet. Uranus was fully revealed, in 1986, by the Voyager 2 mission which showed it like a fine, light blue-green world. Uranus is a pale blue planet because its visible atmosphere contains methane gas and few aerosols or clouds as methane absorbs red wavelengths of incoming sunlight, but allows blue wavelengths to escape back into space. As seen from Earth, Uranus is at the limit of the visual magnitude. Uranus is another gas planet and it's orbiting the Sun in 84 years. Its axis of rotation is strongly tilted by 98 °, hence the planet is seen lying on its side! Four billion years ago, scientists using computer simulation believe a young proto-planet of rock and ice, at least twice de mass of Earth, likely collided with Uranus with a grazing blow, causing its extreme tilt. The impact further might have left molten ice and lopsided lumps of rock within the planet, perhaps explaining its tilted and off-center magnetic field, too as rock and ice thrown into orbit would have then clumped together to form the rings and moons around Uranus. Because of Uranus' extreme axis tilt, its south pole doesn't see sunlight for about 40 years and seasons are really extreme. When Uranus passed its equinox, there was a outbreak of clouds. The best guess about Uranus axis tilt is that it collided with something even bigger or as big during its formation. Voyager 2 found that Uranus had a ring system with two rings. This faraway world has about 27 large and smaller satellites. Uranus has a magnetosphere which is tilted 60° relative to the weird planet's axis as the planet's magnetic tail twists into a helix stretching 6 million miles (10 million kilometers) in the direction pointed away from the Sun. Like Jupiter and Saturn, Uranus is re-emetting more energy than the one it receives from the Sun. In that case, this is due to the rocky core components of Uranus radioactivity. Dynamic winds at Uranus are occurring in a layer no deeper than 680 miles as the atmosphere below is surprisingly calm. Their layers lie under a other, thick one. Atmospheric disturbances are more numerous on Jupiter and Saturn but less strong compared to Uranus or Neptune, for reasons possibly related with compositions and angles between the magnetic fields and rotational axis. The occultation of a bright star by the planet Uranus resulted in the discovery of its thin ring system in 1977
Such a inclination of the magnetic relative to the polar axis is suggesting that the material flows in the planet's interior that are generating the magnetic field are closer to the surface of Uranus than the flows inside Earth, Jupiter and Saturn are to their respective surfaces. Voyager 2 discovered too two shepherd satellites associated with the rings and designated 1986U7 and 1986U8. By observing dips in starlight as a star passed behind Uranus, astronomers knew Uranus had nine narrow rings already from observations made at Earth. Unlike Saturn's icy rings, they found Uranus' rings to be dark gray, reflecting only a few percent of the incident sunlight. 11 new moons were discovered too. As a average temperature at Uranus is about minus 350° Fahrenheit, Voyager showed there was heat transport from pole to pole in Uranus' atmosphere that maintained the same temperature at both poles, even though the Sun was shining directly for decades on one pole and not the other. As Uranus doesn't emit heat, it is possible that that slows internal convection down thence no thunderstorms exist in the planet's weather. One of the satellites discovered by Voyager 2, a icy moon called Miranda, revealed a peculiar, varied landscape and evidence of active geologic, tectonic and thermal activity in the past. While only about 300 miles (500 kilometers) in diameter, this small object boasts giant canyons that could be up to 12 times as deep as the Grand Canyon in Arizona. Miranda also has three unique features called 'coronae,' which are lightly cratered collections of ridges and valleys. Scientists think this moon could have been shattered and then reassembled. Small moons usually tend to cool and freeze over rapidly after their formation. Miranda's surface consists of two strikingly different major types of terrain, one old, heavily cratered, with a relatively uniform albedo, and the other a young, complex terrain characterized by sets of bright and dark bands, scarps and ridges features
NeptuneNeptune is the last of the gas giants. Its size is similar to Uranus'. Methane on Neptune like at Uranus absorbs red wavelengths of incoming sunlight, but allows blue wavelengths to escape back into space, resulting in the predominantly bluish color. Neptune is structured into gas layers as it has a strongest weather activity than the previous planet. The temperature difference between Neptune's strong internal heat source and its frigid cloud tops, about minus 260 degrees Fahrenheit, might trigger instabilities in the atmosphere that drive large-scale weather changes. Clouds at Neptune vary on really short time scales, and that's partly because it has winds that blow hundreds of miles an hour. Because of the 164-year long orbit of the planet, weather studies could not yet see seasonal changes. High-altitude clouds may be observed composed of methane ice crystals. Neptune's brilliant azure blue is due to that methane in its atmosphere absorbs the color red. Should helium be the dominant component in the atmosphere, Neptune would appear white or gray. A faint, dark band near the bottom of the southern hemisphere is probably caused by a decrease in the hazes in the atmosphere that scatter blue light as the band was imaged by NASA's Voyager 2 spacecraft in 1989, and may be tied to circumpolar circulation created by high-velocity winds in that region. Some large spots, similar to those of Jupiter, may be observed. Scienstists suspect that new storms crop up on Neptune every four to six years, and that each storm may last up to six years, though two-year lifespans were more likely. Neptune has the strongest winds in the solar system, with speeds above 1,240 mph (2,000 km/h). Neptune's dark vortices are high-pressure systems and are usually accompanied by bright 'companion clouds.' It is most likely that dark vortices -- as they are ill-known and how fast they rotate -- at Neptune arise from a instability in the sheared eastward and westward winds. Such cyclones at Neptune may wander to the equator or the high latitudes as they are not as tightly constrained by numerous alternating wind jets than at Jupiter. Neptune seems to only have three broad jets: a westward one at the equator, and eastward ones around the north and south poles. The bright clouds form when the flow of ambient air is perturbed and diverted upward over the dark vortex, causing gases to likely freeze into methane ice crystals. Huge, lens-shaped gaseous dark vortices coast through the atmosphere as the companion clouds are similar to so-called orographic clouds at Earth. Neptune's dark vortices have exhibited surprising diversity over the years, in terms of size, shape, and stability. They meander in latitude, and sometimes speed up or slow down. They also come and go on much shorter timescales compared to similar anticyclones seen on Jupiter. Bands of clouds named the 'Great Dark Spot' and its companion bright smudge or a fast moving bright feature called 'Scooter' and a little dark spot were observed like weather features at Neptune by the Voyager 2 mission. The Great Dark Spot features feathery white clouds overlying the boundary of the dark and light blue regions and the general, spiral structure, hints to a storm system rotating counterclockwise. Periodic small scale patterns in the white cloud, possibly waves, are short lived and do not persist from one Neptunian rotation to the next. Neptune has an axis tilt of about 28° as its magnetosphere is tilted by 47° and shifted by half a radius off the planet's center. Such an odd tilt and shift are thought to originate at the planet's internal gas flows, like at Uranus. The giant planet experiences seasons because its axis is tilted. Instead of lasting a few months, each of Neptune's seasons continues for about 40 years. By 2011 Neptune had more clouds than a few years before, when most of the clouds were in the southern hemisphere as the cloud activity is now shifting to the northern hemisphere where it is winter, as early summer in the southern hemisphere. When Herschel had spotted Uranus, he had already noticed that the orbit of the newfound planet did not match the predictions of Newton's theory of gravity. Studying Uranus in 1821, French astronomer Alexis Bouvard speculated that another planet was tugging on the giant planet, altering its motion. In 1841, French Urbain Le Verrier and Briton John Couch Adams, both mathematicians and astronomers, independently predicted the location of that hypothetical planet. As Adams had sent his calculations, by September 1845 to Sir George B. Airy, the Astronomer Royal of England and the latter did not look for the planet as he lacked confidence in Adams. Le Verrier meanwhile sent by mid-1846 a note describing his predicted location of the new planet to German astronomer Johann Gottfried Galle at the Urania Berlin Observatory. Galle had just charted the fixed stars in the area where the planet was believed to be. Over the course of two nights in September 1846, Galle, with his assistant Heinrich L. d'Arrest, found and identified Neptune as a planet, less than a degree from Le Verrier's predicted position. The discovery was hailed as a major success for Newton's theory of gravity and the understanding of the Universe as the discovery doubled the size of the solar system at the time as nowadays both Adams and Leverrier usually are credited with the discovery. Galileo Galilei, in December 1612, while observing Jupiter and its moons with his telescope, had recorded Neptune in his notebook, but as a star. More than a month later, in January 1613, he noted that it appeared to have moved relative to other stars but he however never identified Neptune as a planet, and apparently did not follow up those observations. Neptune has a ring system (which was discovered in 1984 through the occultation of a star by the planet, by NASA's Kuiper Airborne Observatory) and about 30 moons of varied sizes. The planet was first visited by Voyager 2 in 1989. Neptune takes a long 165 years to orbit the Sun! The length of summer, hence the uninterrupted daylight, during 40 years to one of the planet's poles, brings to that the methane in tby 18° F (10° C) as this might be a factor too to the strong winds of Neptune
A lot of Neptune's moons are captured Kuiper Belt objects. Neptune's satellite system has a violent and tortured history. Many billions of years ago, Neptune captured the large moon Triton from the Kuiper Belt, that large region of icy and rocky objects beyond the orbit of Neptune. Triton's gravity would have torn up Neptune's original satellite system. Triton settled into a circular orbit and the debris from shattered Neptunian moons re-coalesced into a second generation of natural satellites. Neptune system features a moon, Triton, its largest one, which possesses a nitrogen-dominated atmosphere, like the Earth or Titan, largest Saturn moon. Most of the nitrogen, at the cold Triton, eventually condensed as frost, making it the only satellite in the solar system known to have a surface made mainly of nitrogen ice. Triton was studied in 1989 when the Voyager 2 flyby passed there. Triton features a wrinkly cantaloupe terrain, the origin of which is unknown, and a set of 'cryovolcanic' landscapes apparently produced by icy-cold liquids (now frozen) erupted from the interior. Nitrogen ice geysers are also found. One side of the Moon only was observed by Voyager 2. Triton might share a lot of common with Pluto. Triton has a retrograde motion on its orbit, hinting to that is was captured by Neptune and likely a former Kuiper Belt object. Triton is one of the coolest bodies in the solar system, with a surface temperature of minus 391 degrees Fahrenheit (minus 235 degrees Celsius). The surface of Triton is extremely young and sparsely cratered, and Triton could be geologically active today as the moon has been ascertained by Voyager 2 to have active geysers, spewing nitrogen ice particules up to 6 miles in altitude, making it one the known active worlds in the outer solar system. Volcanic features and fractures mark its cold, icy surface, likely results from a past tidal heating. A subsurface ocean is considered possible, but unconfirmed. No large mountains nor deep basins are extant. Some resurfacing could be linked to the high internal heat of the moon and the low strength of the surface ices and the surface of Triton thus might by younger than the one of Europe. At the moon's south pole methane ice is supposed to have interacted with sunlight as dark streaks are linked to geysers as the northern hemisphere is featuring the famed 'cantaloupe' terrain which was formed when the ice crust of Triton endured a wholesale overturn. Triton might by doomed in a future as it features a fractured surface like the one at Mars's Phobos, a hint to gravitational disturbance accentuated further through a loosely bound interior. Triton might be a Pluto-like object that Neptune pulled into orbit. Voyager 2 data and a occultation observation in 2001 indicate that Triton’s atmosphere is made mostly of nitrogen and is distorted at different locations by its high winds and strong tides
PlutoPluto is the solar system's ninth and last planet. It was discovered in 1930, from a systematic search along the ecliptic. Pluto is located at the far reaches of the Sun where this faraway planet is completing its orbit in 249 years -two centuries and a half! Pluto's orbit is highly eccentric, and highly inclined by 17° above the ecliptic, the average plane of the solar system. The eccentricity of the orbit takes Pluto sometimes inside the orbit of Neptune. Uncertainty remains about Pluto's orbit, which is due to Pluto’s great distance from the Sun and that we have been studying it for only about one-third of its orbit. Our knowledge of Pluto’s position could be wrong by several thousand miles. Pluto is not a gas giant. It's a rocky planet instead, like Earth or Mercury. It has an atmosphere. Pluto is strongly tilted on its axis by 122°, which means that the planet is lying below the horizontal, with its south pole pointing upwards. Pluto has a thin atmosphere which had been detected by NASA's Kuiper Airborne Observatory. NASA's New Horizons, scheduled to launch in 2006 for an arrival in 2015, will be the first space mission ever to reach there! Some more science about Pluto came about 1985-1900 when Charon, the planet's moon, was seen orbiting edge-on from ground observatories. That moon, of a diameter 648 miles (1,043 km) had been discovered in 1978 at the U.S. Naval Observatory and first resolved using the Hubble Space Telescope in 1990. The moon had remained hidden for 48 years due to its close proximity to Pluto. That largest of Pluto's five moons, Charon, was discovered on June 22, 1978 at the U.S. Naval Observatory in Flagstaff, Arizona, only about six miles from where Pluto itself was discovered at Lowell Observatory. Astronomers were just trying to refine Pluto's orbit around the Sun. The couple Pluto-Charon formed from a giant impact, very much like the Earth-Moon system. The name 'Charon' originally came from that one of the discoverers who wanted to name the moon after his wife, Charlene, known as 'Char.' As he was always thinking about physics, electrons and protons, he added a '-on.' Fortuitously, the name Charon also matched the one of a Greek god. Two more moons to Pluto have been discovered since, Nix and Hydra, in the range of 20 to 70 miles in diameter (32 to 113 km) as discovered by 2005 and a other too by 2011. Kerberos and Styx, further, were discovered in 2011 and 2012 respectively and named after a Internet vote in 2012, approved by the International Astronomical Union (IAU). Kerberos has a estimated diameter of 8 to 21 miles (13 to 34 km) as it is located between the orbits of Nix and Hydra. Styx is irregular in shape and 6 to 15 miles (10-24 kilometers) across, at a 58,000-mile (93,300-km) circular orbit and assumed to be co-planar with the other satellites in the system. Pluto's entire moon system is believed to have formed by a collision billions years ago between Pluto and another planet-sized body from the Kuiper Belt early in the history of the solar system, which further could provide a explanation for why such a small planet holds such a number of satellites. The smashup flung material that coalesced into the family of satellites observed around Pluto. A fifth diminutive moon was found by 2012 as a lot of fragments resulting from the collision are also thought to orbit around. Some are questioning the planetary nature of Pluto, as they think the planet might be better related to the Kuiper Belt, this zone of primordial objects dating back to the formation of the solar system, and found beyond the orbit of Pluto. Winter in a hemisphere at Pluto is lasting 100 years! Charon appears 7 times larger in Pluto's sky than our Moon is looking like for us and five times dimmer. Charon does display a specific cycle of phases during the 6 days and 10 hours that the Pluto's day lasts. Its goes from a wide crescent, to a 'quarter moon,' then to gibbous, and back again
Our solar system has been our backyard since mankind appeared. It now seems not to be so unique in the Universe however. Recentest science thinks that solar systems are inherent to stars' formation. A lot of them, Earth-like planets included, are expected to be found around numerous stars as our solar system, until now, is found remaining unique in its features and characteristics
Website Manager: G. Guichard, site 'Amateur Astronomy,' http://stars5.6te.net. Page Editor: G. Guichard. last edited: 4/7/2020. contact us at ggwebsites@outlook.com
