Planeten sind Regionen von Missionen für bestimmte Gruppen von Schwierigkeiten und Fraktionen. Jeder Planet hat seinen eigenen Satz von Ressourcen und. Ein Planet ist ein großer Himmelskörper, der sich um eine Sonne bewegt. Das Klexikon ist wie eine Wikipedia für Kinder und Schüler. Auch die 17entdeckten Planeten Uranus und Neptun sowie der entdeckte Zwergplanet Pluto – bis
IMP-Schülerinnen erstellen Planeten-WikiPlaneten sind Regionen von Missionen für bestimmte Gruppen von Schwierigkeiten und Fraktionen. Jeder Planet hat seinen eigenen Satz von Ressourcen und. Planeten. • Zwergplaneten. • Natürliche Satelliten. (Monde). • Kleinkörper Verlust des neunten Planeten ☹ pixel-fp.com Und zwar die vier inneren Gesteinsplaneten, die recht klein sind: Merkur, Venus, Erde und Mars. Dann – immer von der Sonne nach außen gesehen – die vier.
Wiki Planeten Navigation menu VideoPlanet Caravan - Black Sabbath For other uses, see Planet (disambiguation). The Planets, Op. 32, is a seven- movement orchestral suite by the English composer Gustav Holst, written between and Each movement of the suite is named after a planet of the solar system and its corresponding astrological character as defined by pixel-fp.com on: Planets in astrology. Een planeet is een hemellichaam dat om een ster beweegt. Planeten hebben genoeg massa om een ronde vorm te benaderen, maar te weinig massa om in hun binnenste tot kernfusie te leiden, zodat ze zelf geen licht geven. In het zonnestelsel bewegen acht planeten om de Zon. De Aarde is daarvan zeer waarschijnlijk de enige waarop leven voorkomt. In het sterrenstelsel waartoe de Zon behoort, de . Planetes (プラネテス Puranetesu?) è un manga di genere fantascientifico di Makoto Yukimura serializzato in Giappone da gennaio a gennaio La serie è stata in seguito raccolta in quattro volumi tankōbon, pubblicati dal 23 gennaio al 23 febbraio L'edizione italiana è stata pubblicata da Panini Comics dal 22 maggio al 17 febbraio
Als Erstes mГchte ich in dieser Kategorie etwas Lachsrückenfilet fГhre. - Auch Leben ist eine Kunst - Der Fall Max EmdenSednaVP
The existence of lightning in the atmosphere of Venus has been controversial  since the first suspected bursts were detected by the Soviet Venera probes    In —07, Venus Express clearly detected whistler mode waves , the signatures of lightning.
Their intermittent appearance indicates a pattern associated with weather activity. According to these measurements, the lightning rate is at least half of that on Earth,  however other instruments have not detected lightning at all.
In , Venus Express discovered that a huge double atmospheric vortex exists at the south pole. In December , and to a lesser extent in April and May , researchers working on Japan's Akatsuki mission observed bow shapes in the atmosphere of Venus.
This was considered direct evidence of the existence of perhaps the largest stationary gravity waves in the solar system. In , Venera 4 found Venus' magnetic field to be much weaker than that of Earth.
This magnetic field is induced by an interaction between the ionosphere and the solar wind ,   rather than by an internal dynamo as in the Earth's core.
Venus' small induced magnetosphere provides negligible protection to the atmosphere against cosmic radiation. The lack of an intrinsic magnetic field at Venus was surprising, given that it is similar to Earth in size and was expected also to contain a dynamo at its core.
A dynamo requires three things: a conducting liquid, rotation, and convection. The core is thought to be electrically conductive and, although its rotation is often thought to be too slow, simulations show it is adequate to produce a dynamo.
On Earth, convection occurs in the liquid outer layer of the core because the bottom of the liquid layer is much higher in temperature than the top.
On Venus, a global resurfacing event may have shut down plate tectonics and led to a reduced heat flux through the crust.
This would cause the mantle temperature to increase, thereby reducing the heat flux out of the core. As a result, no internal geodynamo is available to drive a magnetic field.
Instead, the heat from the core is reheating the crust. One possibility is that Venus has no solid inner core,  or that its core is not cooling, so that the entire liquid part of the core is at approximately the same temperature.
Another possibility is that its core has already completely solidified. The state of the core is highly dependent on the concentration of sulfur , which is unknown at present.
The weak magnetosphere around Venus means that the solar wind is interacting directly with its outer atmosphere. Here, ions of hydrogen and oxygen are being created by the dissociation of neutral molecules from ultraviolet radiation.
The solar wind then supplies energy that gives some of these ions sufficient velocity to escape Venus' gravity field. This erosion process results in a steady loss of low-mass hydrogen, helium, and oxygen ions, whereas higher-mass molecules, such as carbon dioxide, are more likely to be retained.
Atmospheric erosion by the solar wind probably led to the loss of most of Venus' water during the first billion years after it formed.
Venus orbits the Sun at an average distance of about 0. Although all planetary orbits are elliptical , Venus' orbit is the closest to circular , with an eccentricity of less than 0.
All the planets in the Solar System orbit the Sun in an anticlockwise direction as viewed from above Earth's north pole. Most planets also rotate on their axes in an anti-clockwise direction, but Venus rotates clockwise in retrograde rotation once every Earth days—the slowest rotation of any planet.
Because its rotation is so slow, Venus is very close to spherical. Venus' equator rotates at 6. Venus may have formed from the solar nebula with a different rotation period and obliquity, reaching its current state because of chaotic spin changes caused by planetary perturbations and tidal effects on its dense atmosphere, a change that would have occurred over the course of billions of years.
The rotation period of Venus may represent an equilibrium state between tidal locking to the Sun's gravitation, which tends to slow rotation, and an atmospheric tide created by solar heating of the thick Venusian atmosphere.
Venus has no natural satellites. Alex Alemi's and David Stevenson 's study of models of the early Solar System at the California Institute of Technology shows Venus likely had at least one moon created by a huge impact event billions of years ago.
An alternative explanation for the lack of satellites is the effect of strong solar tides, which can destabilize large satellites orbiting the inner terrestrial planets.
To the naked eye , Venus appears as a white point of light brighter than any other planet or star apart from the Sun. Venus "overtakes" Earth every days as it orbits the Sun.
Its greater maximum elongation means it is visible in dark skies long after sunset. As the brightest point-like object in the sky, Venus is a commonly misreported " unidentified flying object ".
As it orbits the Sun, Venus displays phases like those of the Moon in a telescopic view. The planet appears as a small and "full" disc when it is on the opposite side of the Sun at superior conjunction.
Venus shows a larger disc and "quarter phase" at its maximum elongations from the Sun, and appears its brightest in the night sky.
The planet presents a much larger thin "crescent" in telescopic views as it passes along the near side between Earth and the Sun.
Venus displays its largest size and "new phase" when it is between Earth and the Sun at inferior conjunction. Its atmosphere is visible through telescopes by the halo of sunlight refracted around it.
The Venusian orbit is slightly inclined relative to Earth's orbit; thus, when the planet passes between Earth and the Sun, it usually does not cross the face of the Sun.
Transits of Venus occur when the planet's inferior conjunction coincides with its presence in the plane of Earth's orbit.
The latest pair was June 8, and June 5—6, The transit could be watched live from many online outlets or observed locally with the right equipment and conditions.
The preceding pair of transits occurred in December and December ; the following pair will occur in December and December Historically, transits of Venus were important, because they allowed astronomers to determine the size of the astronomical unit , and hence the size of the Solar System as shown by Horrocks in The pentagram of Venus is the path that Venus makes as observed from Earth.
The ratio is approximate. Naked eye observations of Venus during daylight hours exist in several anecdotes and records. Astronomer Edmund Halley calculated its maximum naked eye brightness in , when many Londoners were alarmed by its appearance in the daytime.
French emperor Napoleon Bonaparte once witnessed a daytime apparition of the planet while at a reception in Luxembourg. A long-standing mystery of Venus observations is the so-called ashen light —an apparent weak illumination of its dark side, seen when the planet is in the crescent phase.
The first claimed observation of ashen light was made in , but the existence of the illumination has never been reliably confirmed. Observers have speculated it may result from electrical activity in the Venusian atmosphere, but it could be illusory, resulting from the physiological effect of observing a bright, crescent-shaped object.
Because the movements of Venus appear to be discontinuous it disappears due to its proximity to the sun, for many days at a time, and then reappears on the other horizon , some cultures did not recognize Venus as single entity;  instead, they assumed it to be two separate stars on each horizon: the morning and evening star.
The ancient Greeks also initially believed Venus to be two separate stars: Phosphorus , the morning star, and Hesperus , the evening star. In the second century, in his astronomical treatise Almagest , Ptolemy theorized that both Mercury and Venus are located between the Sun and the Earth.
The 11th-century Persian astronomer Avicenna claimed to have observed the transit of Venus ,  which later astronomers took as confirmation of Ptolemy's theory.
When the Italian physicist Galileo Galilei first observed the planet in the early 17th century, he found it showed phases like the Moon, varying from crescent to gibbous to full and vice versa.
When Venus is furthest from the Sun in the sky, it shows a half-lit phase , and when it is closest to the Sun in the sky, it shows as a crescent or full phase.
This could be possible only if Venus orbited the Sun, and this was among the first observations to clearly contradict the Ptolemaic geocentric model that the Solar System was concentric and centred on Earth.
The atmosphere of Venus was discovered in by Russian polymath Mikhail Lomonosov. He correctly surmised this was due to scattering of sunlight in a dense atmosphere.
Later, American astronomer Chester Smith Lyman observed a complete ring around the dark side of the planet when it was at inferior conjunction , providing further evidence for an atmosphere.
Little more was discovered about Venus until the 20th century. Its almost featureless disc gave no hint what its surface might be like, and it was only with the development of spectroscopic , radar and ultraviolet observations that more of its secrets were revealed.
The first ultraviolet observations were carried out in the s, when Frank E. Ross found that ultraviolet photographs revealed considerable detail that was absent in visible and infrared radiation.
He suggested this was due to a dense, yellow lower atmosphere with high cirrus clouds above it. Spectroscopic observations in the s gave the first clues about the Venusian rotation.
Vesto Slipher tried to measure the Doppler shift of light from Venus, but found he could not detect any rotation. He surmised the planet must have a much longer rotation period than had previously been thought.
Radar observations of Venus were first carried out in the s, and provided the first measurements of the rotation period, which were close to the modern value.
Radar observations in the s revealed details of the Venusian surface for the first time. The observations also revealed a bright region attributed to mountains, which was called Maxwell Montes.
The first robotic space probe mission to Venus, and the first to any planet, began with the Soviet Venera program in On 18 October , the Soviet Venera 4 successfully entered the atmosphere and deployed science experiments.
In , Mariner 10 swung by Venus on its way to Mercury and took ultraviolet photographs of the clouds, revealing the extraordinarily high wind speeds in the Venusian atmosphere.
In , the Soviet Venera 9 and 10 landers transmitted the first images from the surface of Venus, which were in black and white. Equipped with seven scientific instruments, Venus Express provided unprecedented long-term observation of Venus' atmosphere.
ESA concluded that mission in December It would be controlled by a mechanical computer and driven by wind power. Venus is a primary feature of the night sky, and so has been of remarkable importance in mythology , astrology and fiction throughout history and in different cultures.
In Sumerian religion , Inanna was associated with the planet Venus. The planet Venus appears to make a similar descent, setting in the West and then rising again in the East.
Classical poets such as Homer , Sappho , Ovid and Virgil spoke of the star and its light. Shukra which is used in Indian Vedic astrology  means "clear, pure" or "brightness, clearness" in Sanskrit.
One of the nine Navagraha , it is held to affect wealth, pleasure and reproduction; it was the son of Bhrgu , preceptor of the Daityas, and guru of the Asuras.
Venus is known as Kejora in Indonesian and Malaysian Malay. The Maya considered Venus to be the most important celestial body after the Sun and Moon.
The Ancient Egyptians and Greeks believed Venus to be two separate bodies, a morning star and an evening star. The Egyptians knew the morning star as Tioumoutiri and the evening star as Ouaiti.
With the invention of the telescope, the idea that Venus was a physical world and possible destination began to take form.
The impenetrable Venusian cloud cover gave science fiction writers free rein to speculate on conditions at its surface; all the more so when early observations showed that not only was it similar in size to Earth, it possessed a substantial atmosphere.
Closer to the Sun than Earth, the planet was frequently depicted as warmer, but still habitable by humans.
Findings from the first missions to Venus showed the reality to be quite different, and brought this particular genre to an end.
The astronomical symbol for Venus is the same as that used in biology for the female sex: a circle with a small cross beneath.
Speculation on the possibility of life on Venus's surface decreased significantly after the early s, when it became clear that the conditions are extreme compared to those on Earth.
Venus's extreme temperature and atmospheric pressure make water-based life as currently known unlikely. Some scientists have speculated that thermoacidophilic extremophile microorganisms might exist in the cooler, acidic upper layers of the Venusian atmosphere.
Morowitz suggested in a Nature article that tiny objects detected in Venus's clouds might be organisms similar to Earth's bacteria which are of approximately the same size :.
Se non sei in grado di riempirlo in buona parte, non fare nulla; non inserire template vuoti. Portale Musica : accedi alle voci di Wikipedia che trattano di musica.
Because the eccentricity of its orbit is 0. The axial tilt of Jupiter is relatively small: only 3. As a result, it does not experience significant seasonal changes, in contrast to, for example, Earth and Mars.
Jupiter's rotation is the fastest of all the Solar System's planets, completing a rotation on its axis in slightly less than ten hours; this creates an equatorial bulge easily seen through an Earth-based amateur telescope.
The planet is shaped as an oblate spheroid , meaning that the diameter across its equator is longer than the diameter measured between its poles.
Because Jupiter is not a solid body, its upper atmosphere undergoes differential rotation. System II applies at all latitudes north and south of these; its period is 9h 55m System III was first defined by radio astronomers , and corresponds to the rotation of the planet's magnetosphere; its period is Jupiter's official rotation.
Jupiter is usually the fourth brightest object in the sky after the Sun, the Moon and Venus ;  at times Mars is brighter than Jupiter.
Earth overtakes Jupiter every As it does so, Jupiter appears to undergo retrograde motion with respect to the background stars.
That is, for a period Jupiter seems to move backward in the night sky, performing a looping motion. Because the orbit of Jupiter is outside that of Earth, the phase angle of Jupiter as viewed from Earth never exceeds It was only during spacecraft missions to Jupiter that crescent views of the planet were obtained.
The planet Jupiter has been known since ancient times. It is visible to the naked eye in the night sky and can occasionally be seen in the daytime when the Sun is low.
They used Jupiter's roughly year orbit along the ecliptic to define the constellations of their zodiac. The astronomical symbol for the planet, , is a stylized representation of the god's lightning bolt.
The original Greek deity Zeus supplies the root zeno- , used to form some Jupiter-related words, such as zenographic.
Jovian is the adjectival form of Jupiter. The older adjectival form jovial , employed by astrologers in the Middle Ages , has come to mean "happy" or "merry", moods ascribed to Jupiter's astrological influence.
In Vedic astrology , Hindu astrologers named the planet after Brihaspati , the religious teacher of the gods, and often called it " Guru ", which literally means the "Heavy One".
In Central Asian Turkic myths , Jupiter is called Erendiz or Erentüz , from eren of uncertain meaning and yultuz "star". There are many theories about the meaning of eren.
These peoples calculated the period of the orbit of Jupiter as 11 years and days. They believed that some social and natural events connected to Erentüz's movements on the sky.
The observation of Jupiter dates back to at least the Babylonian astronomers of the 7th or 8th century BC. By the 4th century BC, these observations had developed into the Chinese zodiac ,  with each year associated with a Tai Sui star and god controlling the region of the heavens opposite Jupiter's position in the night sky; these beliefs survive in some Taoist religious practices and in the East Asian zodiac's twelve animals, now often popularly assumed to be related to the arrival of the animals before Buddha.
If accurate, this would predate Galileo's discovery by nearly two millennia. In , Italian polymath Galileo Galilei discovered the four largest moons of Jupiter now known as the Galilean moons using a telescope; thought to be the first telescopic observation of moons other than Earth's.
One day after Galileo, Simon Marius independently discovered moons around Jupiter, though he did not publish his discovery in a book until These findings were also the first discovery of celestial motion not apparently centered on Earth.
The discovery was a major point in favor of Copernicus' heliocentric theory of the motions of the planets; Galileo's outspoken support of the Copernican theory placed him under the threat of the Inquisition.
During the s, Giovanni Cassini used a new telescope to discover spots and colorful bands on Jupiter and observed that the planet appeared oblate; that is, flattened at the poles.
He was also able to estimate the rotation period of the planet. The Great Red Spot, a prominent oval-shaped feature in the southern hemisphere of Jupiter, may have been observed as early as by Robert Hooke and in by Cassini, although this is disputed.
The pharmacist Heinrich Schwabe produced the earliest known drawing to show details of the Great Red Spot in The Red Spot was reportedly lost from sight on several occasions between and before becoming quite conspicuous in It was recorded as fading again in and at the start of the 20th century.
Both Giovanni Borelli and Cassini made careful tables of the motions of Jupiter's moons, allowing predictions of the times when the moons would pass before or behind the planet.
In , E. The discovery of this relatively small object, a testament to his keen eyesight, quickly made him famous. This moon was later named Amalthea.
In , Rupert Wildt identified absorption bands of ammonia and methane in the spectra of Jupiter. Three long-lived anticyclonic features termed white ovals were observed in For several decades they remained as separate features in the atmosphere, sometimes approaching each other but never merging.
Finally, two of the ovals merged in , then absorbed the third in , becoming Oval BA. In , Bernard Burke and Kenneth Franklin detected bursts of radio signals coming from Jupiter at Radio bursts from Jupiter were found to come in two forms: long bursts or L-bursts lasting up to several seconds, and short bursts or S-bursts that had a duration of less than a hundredth of a second.
Since , a number of automated spacecraft have visited Jupiter, most notably the Pioneer 10 space probe, the first spacecraft to get close enough to Jupiter to send back revelations about the properties and phenomena of the Solar System's largest planet.
Entering a Hohmann transfer orbit from Earth to Jupiter from low Earth orbit requires a delta-v of 6. Beginning in , several spacecraft have performed planetary flyby maneuvers that brought them within observation range of Jupiter.
The Pioneer missions obtained the first close-up images of Jupiter's atmosphere and several of its moons. They discovered that the radiation fields near the planet were much stronger than expected, but both spacecraft managed to survive in that environment.
The trajectories of these spacecraft were used to refine the mass estimates of the Jovian system. Radio occultations by the planet resulted in better measurements of Jupiter's diameter and the amount of polar flattening.
Six years later, the Voyager missions vastly improved the understanding of the Galilean moons and discovered Jupiter's rings.
They also confirmed that the Great Red Spot was anticyclonic. Comparison of images showed that the Red Spot had changed hue since the Pioneer missions, turning from orange to dark brown.
A torus of ionized atoms was discovered along Io's orbital path, and volcanoes were found on the moon's surface, some in the process of erupting.
As the spacecraft passed behind the planet, it observed flashes of lightning in the night side atmosphere. The next mission to encounter Jupiter was the Ulysses solar probe.
It performed a flyby maneuver to attain a polar orbit around the Sun. During this pass, the spacecraft conducted studies on Jupiter's magnetosphere.
Ulysses has no cameras so no images were taken. A second flyby six years later was at a much greater distance. In , the Cassini probe flew by Jupiter on its way to Saturn , and provided some of the highest-resolution images ever made of the planet.
The New Horizons probe flew by Jupiter for a gravity assist en route to Pluto. Its closest approach was on February 28, The first spacecraft to orbit Jupiter was the Galileo probe, which entered orbit on December 7, The spacecraft also witnessed the impact of Comet Shoemaker—Levy 9 as it approached Jupiter in , giving a unique vantage point for the event.
Its originally designed capacity was limited by the failed deployment of its high-gain radio antenna, although extensive information was still gained about the Jovian system from Galileo.
A kilogram titanium atmospheric probe was released from the spacecraft in July , entering Jupiter's atmosphere on December 7. NASA's Juno mission arrived at Jupiter on July 4, and was expected to complete thirty-seven orbits over the next twenty months.
There has been great interest in studying the icy moons in detail because of the possibility of subsurface liquid oceans on Jupiter's moons Europa, Ganymede, and Callisto.
Funding difficulties have delayed progress. Jupiter has 79 known natural satellites. The four largest moons, visible from Earth with binoculars on a clear night, known as the " Galilean moons ", are Io, Europa, Ganymede, and Callisto.
The orbits of three of them Io, Europa, and Ganymede form a pattern known as a Laplace resonance ; for every four orbits that Io makes around Jupiter, Europa makes exactly two orbits and Ganymede makes exactly one.
This resonance causes the gravitational effects of the three large moons to distort their orbits into elliptical shapes, because each moon receives an extra tug from its neighbors at the same point in every orbit it makes.
The tidal force from Jupiter, on the other hand, works to circularize their orbits. The eccentricity of their orbits causes regular flexing of the three moons' shapes, with Jupiter's gravity stretching them out as they approach it and allowing them to spring back to more spherical shapes as they swing away.
This tidal flexing heats the moons' interiors by friction. This is seen most dramatically in the extraordinary volcanic activity of innermost Io which is subject to the strongest tidal forces , and to a lesser degree in the geological youth of Europa's surface indicating recent resurfacing of the moon's exterior.
Before the discoveries of the Voyager missions, Jupiter's moons were arranged neatly into four groups of four, based on commonality of their orbital elements.
Since then, the large number of new small outer moons has complicated this picture. There are now thought to be six main groups, although some are more distinct than others.
A basic sub-division is a grouping of the eight inner regular moons, which have nearly circular orbits near the plane of Jupiter's equator and are thought to have formed with Jupiter.
The remainder of the moons consist of an unknown number of small irregular moons with elliptical and inclined orbits, which are thought to be captured asteroids or fragments of captured asteroids.
Irregular moons that belong to a group share similar orbital elements and thus may have a common origin, perhaps as a larger moon or captured body that broke up.
Jupiter has a faint planetary ring system composed of three main segments: an inner torus of particles known as the halo, a relatively bright main ring, and an outer gossamer ring.
Material that would normally fall back to the moon is pulled into Jupiter because of its strong gravitational influence.
The orbit of the material veers towards Jupiter and new material is added by additional impacts. Along with the Sun, the gravitational influence of Jupiter has helped shape the Solar System.
The orbits of most of the system's planets lie closer to Jupiter's orbital plane than the Sun's equatorial plane Mercury is the only planet that is closer to the Sun's equator in orbital tilt , the Kirkwood gaps in the asteroid belt are mostly caused by Jupiter, and the planet may have been responsible for the Late Heavy Bombardment of the inner Solar System's history.
Along with its moons, Jupiter's gravitational field controls numerous asteroids that have settled into the regions of the Lagrangian points preceding and following Jupiter in its orbit around the Sun.
These are known as the Trojan asteroids , and are divided into Greek and Trojan "camps" to commemorate the Iliad. The first of these, Achilles , was discovered by Max Wolf in ; since then more than two thousand have been discovered.
Most short-period comets belong to the Jupiter family—defined as comets with semi-major axes smaller than Jupiter's.
Jupiter family comets are thought to form in the Kuiper belt outside the orbit of Neptune. During close encounters with Jupiter their orbits are perturbed into a smaller period and then circularized by regular gravitational interaction with the Sun and Jupiter.
Due to the magnitude of Jupiter's mass, the center of gravity between it and the Sun lies just above the Sun's surface. Jupiter has been called the Solar System's vacuum cleaner,  because of its immense gravity well and location near the inner Solar System.
It receives the most frequent comet impacts of the Solar System's planets. A survey of early astronomical records and drawings suggested that a certain dark surface feature discovered by astronomer Giovanni Cassini in may have been an impact scar.
The survey initially produced eight more candidate sites as potential impact observations that he and others had recorded between and It was later determined, however, that these candidate sites had little or no possibility of being the results of the proposed impacts.
From Wikipedia, the free encyclopedia. This article is about the planet. Da Wikipedia, l'enciclopedia libera. URL consultato il 9 settembre Herold, He also believed that the orbits of planets are elliptical.
In , Nilakantha Somayaji of the Kerala school of astronomy and mathematics , in his Tantrasangraha , revised Aryabhata's model. Most astronomers of the Kerala school who followed him accepted his planetary model.
In the 11th century, the transit of Venus was observed by Avicenna , who established that Venus was, at least sometimes, below the Sun.
With the advent of the Scientific Revolution , use of the term "planet" changed from something that moved across the sky in relation to the star field ; to a body that orbited Earth or that was believed to do so at the time ; and by the 18th century to something that directly orbited the Sun when the heliocentric model of Copernicus , Galileo and Kepler gained sway.
Thus, Earth became included in the list of planets,  whereas the Sun and Moon were excluded. At first, when the first satellites of Jupiter and Saturn were discovered in the 17th century, the terms "planet" and "satellite" were used interchangeably — although the latter would gradually become more prevalent in the following century.
In the 19th century astronomers began to realize that recently discovered bodies that had been classified as planets for almost half a century such as Ceres , Pallas , Juno , and Vesta were very different from the traditional ones.
These bodies shared the same region of space between Mars and Jupiter the asteroid belt , and had a much smaller mass; as a result they were reclassified as " asteroids ".
In the absence of any formal definition, a "planet" came to be understood as any "large" body that orbited the Sun.
Because there was a dramatic size gap between the asteroids and the planets, and the spate of new discoveries seemed to have ended after the discovery of Neptune in , there was no apparent need to have a formal definition.
In the 20th century, Pluto was discovered. After initial observations led to the belief that it was larger than Earth,  the object was immediately accepted as the ninth planet.
Further monitoring found the body was actually much smaller: in , Ray Lyttleton suggested that Pluto may be an escaped satellite of Neptune ,  and Fred Whipple suggested in that Pluto may be a comet.
Then, on October 6, , Michel Mayor and Didier Queloz of the Geneva Observatory announced the first definitive detection of an exoplanet orbiting an ordinary main-sequence star 51 Pegasi.
The discovery of extrasolar planets led to another ambiguity in defining a planet: the point at which a planet becomes a star. Many known extrasolar planets are many times the mass of Jupiter, approaching that of stellar objects known as brown dwarfs.
Brown dwarfs are generally considered stars due to their ability to fuse deuterium , a heavier isotope of hydrogen. Although objects more massive than 75 times that of Jupiter fuse hydrogen, objects of only 13 Jupiter masses can fuse deuterium.
Deuterium is quite rare, and most brown dwarfs would have ceased fusing deuterium long before their discovery, making them effectively indistinguishable from supermassive planets.
With the discovery during the latter half of the 20th century of more objects within the Solar System and large objects around other stars, disputes arose over what should constitute a planet.
There were particular disagreements over whether an object should be considered a planet if it was part of a distinct population such as a belt , or if it was large enough to generate energy by the thermonuclear fusion of deuterium.
A growing number of astronomers argued for Pluto to be declassified as a planet, because many similar objects approaching its size had been found in the same region of the Solar System the Kuiper belt during the s and early s.
Pluto was found to be just one small body in a population of thousands. Some of them, such as Quaoar , Sedna , and Eris , were heralded in the popular press as the tenth planet , failing to receive widespread scientific recognition.
Acknowledging the problem, the IAU set about creating the definition of planet , and produced one in August The number of planets dropped to the eight significantly larger bodies that had cleared their orbit Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune , and a new class of dwarf planets was created, initially containing three objects Ceres , Pluto and Eris.
There is no official definition of extrasolar planets. The positions statement incorporates the following guidelines, mostly focused upon the boundary between planets and brown dwarfs: .
This working definition has since been widely used by astronomers when publishing discoveries of exoplanets in academic journals.
It does not address the dispute over the lower mass limit,  and so it steered clear of the controversy regarding objects within the Solar System.
This definition also makes no comment on the planetary status of objects orbiting brown dwarfs, such as 2Mb. One definition of a sub-brown dwarf is a planet-mass object that formed through cloud collapse rather than accretion.
This formation distinction between a sub-brown dwarf and a planet is not universally agreed upon; astronomers are divided into two camps as whether to consider the formation process of a planet as part of its division in classification.
For example, a planet formed by accretion around a star may get ejected from the system to become free-floating, and likewise a sub-brown dwarf that formed on its own in a star cluster through cloud collapse may get captured into orbit around a star.
The 13 Jupiter-mass cutoff represents an average mass rather than a precise threshold value. Large objects will fuse most of their deuterium and smaller ones will fuse only a little, and the 13 M J value is somewhere in between.
Another criterion for separating planets and brown dwarfs, rather than deuterium fusion, formation process or location, is whether the core pressure is dominated by coulomb pressure or electron degeneracy pressure.
After much debate and one failed proposal, a large majority of those remaining at the meeting voted to pass a resolution.
The resolution defines planets within the Solar System as follows: . A "planet"  is a celestial body that a is in orbit around the Sun, b has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium nearly round shape, and c has cleared the neighbourhood around its orbit.
Under this definition, the Solar System is considered to have eight planets. Bodies that fulfill the first two conditions but not the third such as Ceres, Pluto, and Eris are classified as dwarf planets , provided they are not also natural satellites of other planets.
Originally an IAU committee had proposed a definition that would have included a much larger number of planets as it did not include c as a criterion.
This definition is based in theories of planetary formation, in which planetary embryos initially clear their orbital neighborhood of other smaller objects.
As described by astronomer Steven Soter : . The IAU definition presents some challenges for exoplanets because the language is specific to the Solar System and because the criteria of roundness and orbital zone clearance are not presently observable.
Astronomer Jean-Luc Margot proposed a mathematical criterion that determines whether an object can clear its orbit during the lifetime of its host star, based on the mass of the planet, its semimajor axis, and the mass of its host star.
The table below lists Solar System bodies once considered to be planets but no longer considered as such by the IAU, as well as whether they would be considered planets under Stern's and definitions.
Ceres was subsequently classified by the IAU as a dwarf planet in The reporting of newly discovered large Kuiper belt objects as planets - particularly Eris - triggered the August IAU decision on what a planet is.
The names for the planets in the Western world are derived from the naming practices of the Romans, which ultimately derive from those of the Greeks and the Babylonians.
In ancient Greece , the two great luminaries the Sun and the Moon were called Helios and Selene ; the farthest planet Saturn was called Phainon , the shiner; followed by Phaethon Jupiter , "bright"; the red planet Mars was known as Pyroeis , the "fiery"; the brightest Venus was known as Phosphoros , the light bringer; and the fleeting final planet Mercury was called Stilbon , the gleamer.
The Greeks also made each planet sacred to one among their pantheon of gods, the Olympians : Helios and Selene were the names of both planets and gods; Phainon was sacred to Cronus , the Titan who fathered the Olympians; Phaethon was sacred to Zeus , Cronus's son who deposed him as king; Pyroeis was given to Ares , son of Zeus and god of war; Phosphoros was ruled by Aphrodite , the goddess of love; and Hermes , messenger of the gods and god of learning and wit, ruled over Stilbon.
The Greek practice of grafting their gods' names onto the planets was almost certainly borrowed from the Babylonians. The Babylonians named Phosphoros after their goddess of love, Ishtar ; Pyroeis after their god of war, Nergal , Stilbon after their god of wisdom Nabu , and Phaethon after their chief god, Marduk.
For instance, the Babylonian Nergal was a god of war, and thus the Greeks identified him with Ares. Unlike Ares, Nergal was also god of pestilence and the underworld.
Today, most people in the western world know the planets by names derived from the Olympian pantheon of gods. Although modern Greeks still use their ancient names for the planets, other European languages, because of the influence of the Roman Empire and, later, the Catholic Church , use the Roman Latin names rather than the Greek ones.
The Romans, who, like the Greeks, were Indo-Europeans , shared with them a common pantheon under different names but lacked the rich narrative traditions that Greek poetic culture had given their gods.
During the later period of the Roman Republic , Roman writers borrowed much of the Greek narratives and applied them to their own pantheon, to the point where they became virtually indistinguishable.
Uranus is unique in that it is named for a Greek deity rather than his Roman counterpart. Some Romans , following a belief possibly originating in Mesopotamia but developed in Hellenistic Egypt , believed that the seven gods after whom the planets were named took hourly shifts in looking after affairs on Earth.
Because each day was named by the god that started it, this is also the order of the days of the week in the Roman calendar after the Nundinal cycle was rejected — and still preserved in many modern languages.
Earth is the only planet whose name in English is not derived from Greco-Roman mythology. Because it was only generally accepted as a planet in the 17th century,  there is no tradition of naming it after a god.
The same is true, in English at least, of the Sun and the Moon, though they are no longer generally considered planets. The name originates from the 8th century Anglo-Saxon word erda , which means ground or soil and was first used in writing as the name of the sphere of Earth perhaps around Many of the Romance languages retain the old Roman word terra or some variation of it that was used with the meaning of "dry land" as opposed to "sea".
Non-European cultures use other planetary-naming systems. China and the countries of eastern Asia historically subject to Chinese cultural influence such as Japan, Korea and Vietnam use a naming system based on the five Chinese elements : water Mercury , metal Venus , fire Mars , wood Jupiter and earth Saturn.
It is not known with certainty how planets are formed. The prevailing theory is that they are formed during the collapse of a nebula into a thin disk of gas and dust.
A protostar forms at the core, surrounded by a rotating protoplanetary disk. Through accretion a process of sticky collision dust particles in the disk steadily accumulate mass to form ever-larger bodies.
Local concentrations of mass known as planetesimals form, and these accelerate the accretion process by drawing in additional material by their gravitational attraction.
These concentrations become ever denser until they collapse inward under gravity to form protoplanets. When the protostar has grown such that it ignites to form a star , the surviving disk is removed from the inside outward by photoevaporation , the solar wind , Poynting—Robertson drag and other effects.
Protoplanets that have avoided collisions may become natural satellites of planets through a process of gravitational capture, or remain in belts of other objects to become either dwarf planets or small bodies.
The energetic impacts of the smaller planetesimals as well as radioactive decay will heat up the growing planet, causing it to at least partially melt.
The interior of the planet begins to differentiate by mass, developing a denser core. With the discovery and observation of planetary systems around stars other than the Sun, it is becoming possible to elaborate, revise or even replace this account.
The level of metallicity —an astronomical term describing the abundance of chemical elements with an atomic number greater than 2 helium —is now thought to determine the likelihood that a star will have planets.
According to the IAU definition , there are eight planets in the Solar System, which are in increasing distance from the Sun :.
Jupiter is the largest, at Earth masses, whereas Mercury is the smallest, at 0. The number of geophysical planets in the solar system is unknown - previously considered to be potentially in the hundreds, but now only estimated at only the low double digits.
An exoplanet extrasolar planet is a planet outside the Solar System. As of 1 December , there are 4, confirmed exoplanets in 3, systems , with systems having more than one planet.
These pulsar planets are believed to have formed from the unusual remnants of the supernova that produced the pulsar, in a second round of planet formation, or else to be the remaining rocky cores of giant planets that survived the supernova and then decayed into their current orbits.Ein Planet (des Sonnensystems) ist gemäß der Definition der Internationalen Astronomischen Union (IAU) ein Himmelskörper,. (a) der sich auf einer. Auch die 17entdeckten Planeten Uranus und Neptun sowie der entdeckte Zwergplanet Pluto – bis Planeten sind Regionen von Missionen für bestimmte Gruppen von Schwierigkeiten und Fraktionen. Jeder Planet hat seinen eigenen Satz von Ressourcen und. Ein Planet ist ein stellares Objekt, welches in der Regel einen Stern auf einer Umlaufbahn. A wikia for the online Pokemon MMORPG Pokemon Planet run by players Note: Not all of this may be correct or up to date. The Planets Orchestral suite by Gustav Holst First UK edition Opus32 Based onPlanets in astrology Composed –16 Movementsseven ScoringOrchestra Premiere Date29 September LocationQueen's Hall, London ConductorAdrian Boult The Planets, Op. 32, is a seven-movement orchestral suite by the English composer Gustav Holst, written between and Each movement of the suite is named after a planet of the solar system and its corresponding astrological character as defined by Holst. Mercury is the smallest and innermost planet in the Solar pixel-fp.com orbit around the Sun takes Earth days, the shortest of all the planets in the Solar System. It is named after the Greek god Hermes (Ερμής), translated into Latin Mercurius Mercury, god of commerce, messenger of the gods, mediator between gods and mortals. 1 "Here to kill!" - PLANET//SHAPER Information: Appearance: How to Obtain: Fun Fact: This stand was named after the Pose Music,  which was an Album and song made by Camellia. Planet Shaper has deep purple accessories on such as a belt, a hat with cat ears, and wristbands. The stand itself is a solid, smooth, lighter red color. The stand has large, neon yellow claws and a neon. Planeten hebben genoeg massa om een ronde vorm te benaderen, maar te weinig massa om in hun binnenste tot kernfusie te leiden, zodat ze zelf geen licht geven. In het zonnestelsel bewegen acht planeten om de Zon. De Aarde is daarvan zeer waarschijnlijk de enige waarop leven voorkomt.