Planet

of these articles is occupied with the heavenly body, for the Austrian party newspaper of the Greens alternative, sees to planet (the Green)

a planet is a heavenly body, that not shines itself andin a keplerschen orbit around a star moves. The name comes from Greek „plánetes “and means „the Umherschweifenden “and/or. „the Wanderer “(old-Greek). In former times planets were called also change stars. Most planets of the solar system become from moons circle.

First soft landing on another planet succeeded to mankind to 15. December 1970 on the Venus with the Soviet probe Venera-7. With Venera-3 and Venera-4 before first hard and nearly-soft planet landings arrive at the 1. March 1966 and to 18.October 1967, whereby Venera-4 successfully transmitted data over the entire period of operation from 96 minutes from the Venus atmosphere.

End 20. Century the first planet was discovered outside of the solar system (Exoplaneten), which circles the star 51 Pegasi. The numbersince that time the well-known Exoplaneten rose strongly.

planets of our solar system

major item: Solar system

• earth something similar (rocky) planets (internal planet system):
  • 1 Merkur
  • 2 Venus
  • 3 earth
  • 4 Mars
• Ioviani planets/ gas giant (exterior planet system):
  • 5 Jupiter
  • 6 Saturn
  • 7 Uranus
  • 8 Neptun
• Transneptuni objects (TNOs):
  • 9 Pluto

Additionally the object could 2003 PRACTICES ₃₁₃ as the tenth planet to this list to be taken up. However the status of the object is finally clarified so far not yet of the IAU.

The middle distancesthe planets to the sun can be indicated quite exactly as the Titius Bode row. Between Mars and Jupiter gapes here a gap, which is filled by the Asteroidengürtel; however the distance of the Neptuns does not arise in the row.

Grouping

of the Asteroidengürtel separates the inside from the outside planet system. The large range of the TNOs is regarded every now and then also as a third zone. Thus rank Merkur, Venus, earth and Mars among the internal planets, and Jupiter, Saturn, Uranus, Neptunand Pluto to the outside planets, whereby the status of Pluto as planet is however disputed. This distinction is not to confound with the grouping into the lower planets, which rotate the sun within the Earth's orbit - thusMerkur and Venus - and into the upper planets, which move outside of the Earth's orbit.

One wants the planets observes needs one depending upon size and distance of the Planets of telescopes of 3 " (Jupiter, Saturn, Mars, Venus) to 12 " opening diameters(Uranus, Neptun, Pluto, Merkur).

the planets and their sequence to notice there also some noticing sayings are noticing rules around itself, z. B.: „My father explains each Saturday our nine planets to me. “

definition

it givesto today no clearly defined distinguisher between planets and Asteroiden. Like that the planet status of Pluto is disputed due to its small size and its strongly elliptical as well as against the ecliptic bent course. Many astronomers add it to the Kuipergürtel, oneReservoir of comets and Asteroiden, which on the inside to to the Neptun - course near-hands. Recently similarly large heavenly bodies in the Kuipergürtel discovered, in particular 2003 PRACTICE ₃₁₃, the discussion around Plutos status again kindled.

the two most frequentDefinition attempts

1. A plausible explanation for the definition of a planet gives the California institutes to OF Technology, which works closely with NASA together:

An object in the solar system is called planet, if it has a larger mass than all differentObjects together, which are in the same orbit.

Thus the earth is a planet, since it is heavier than all Asteroiden in the same orbit as the earth.

Problem: Pluto is the largest object in its environment, however notmore heavily than the sum of its neighbour objects, why it according to this definition not when planet can be classified. If one ranks Pluto among Neptuns orbit, then becomes still clearer this. Afterwards our solar system would have instead of nine thus only eight planets.

2. Other onedefine planets as

rock ball, which formed itself due to the own gravitation to such.

Problem here: This definition would exclude but became the most Asteroiden and comets, all large moons, also the ground connection moon, in addition to count andour solar system would have hundreds of planets.

, In the year 2004 a committee used the international ones astronomical union (IAU), responsible for the naming of heavenly bodies, which is to compile obligatory criteria for the definition of a planet. In the summer 2006 are the resultsthese work to be published.

The most important well-known characteristics of the planets of the solar system are tabular seized under planet ( table).

history of the discovery

planet of the solar system

the planets Merkur, Venus, Mars, Jupiter and Saturn are with the naked eye identifiable by the night sky and appear brighter as most fixed stars. They were in the antique one well-known and by many cultures with their main Gods were already identified. The names used this very day originate from that Roman mythology.

Although there were 16 already in the antique representatives of the Heliozentri conception of the world ( for example Aristarchos of Samos), became to center . Century generally accepted that the planets move with the sun around the earth (Geocentric conception of the world). 1543 published Nikolaus Kopernikus, lively by Aristarchos, its work „from the revolutions of the celestial spheres “, in which he placed the sun into the center and which earth recognized as the further planet.

Under favorable conditions is Uranus alsowith the naked eye to recognize, and he was already listed 1690 falsely as star. It was recognized only 1781 of Sir Friedrich William Herschel as planet. With the help of the older observations it succeeded to Johann Elert Bode the orbit exactly toodetermine. On the basis Urbain Jean Joseph Leverrier and John couch of Adam computed by orbit/trajectory disturbances of the Uranus independently the course of a further planet, this led to 23. September 1846 for discovery Neptuns by Johann Gottfried Galle. By the again discovered planethowever all irregularities in the uranium US course could not be explained.

Finally 1930 of Clyde became W. Tombaugh a further object discovers and late Pluto mentioned, which so far as the ninth planet is considered. The existence of a further planet (Transpluto or Planet X) in the solar system was considered for a long time as improbable.

Since end of the 1990er years objects are discovered appreciably beyond the Neptun and/or the Plutobahn. These transneptunischen objects are likewise called occasionally of the press planet. So for example Quaoar (2002), Orcus (2004) Sedna (2004) or 2003UB ₃₁₃ (2005).

See also: Zeitlinie of the discoveries of planets of the solar system and its natural satellites

Exoplaneten

major item: Exoplanet

the first planets at all, which were discovered outside of our solar system, circle that Pulsar with the name PSR 1257+12. By precise measurements of the return time of the jet, which reaches us from the Pulsar, 1992 two planets with masses could be proven by 4,3 and 3,9 earth masses and 1994 third with 0,02 earth masses. Upthis planets is practically excluded life, like we it from the earth.

The first Exoplanet in an orbit around a sun-similar star became 1995 of professor Michel Mayor of the section for astronomy of the University of Geneva and its coworker Didier Queloz with the help of the radial velocity method discovers. The planet rotates in the 4,2-Tagestakt around that approx. And 0.46 Jupitermassen have 40 light-years distant star Pegasus 51.

In May 2005 156 specially-solar planets were in 136 systems well-known, among them 13 systems alsotwo, two systems with 3 and 1 system with 4 planets (none with more). In the periphery of approx. 100 Parsec were found up to now around 7% of the stars planets. Most of the systems discovered up to now are however not alsoour solar system comparably, with the planets concerns usually gas giants, that circle their central star in a very close orbit. Such planets called by astronomers hot Jupiters. According to a theory they, like Jupiter, are in relatively large distancefrom their central star in the Akkretionsscheibe developed, then however inward moved. According to another theory they are however condensed like stars from a gas cloud.

Exoplaneten in the orbit around sun-similar stars could not be observed until 2005 with telescopes directly,since they are very faint. They are over-radiated by the star brighter around a multiple, around which they circle. The resolving power of earthsupported telescopes is not sufficient today yet relative to, around two so close together lying objects with soto represent large brightness difference as a planet and its star separately. One uses therefore different indirect methods like the transit method, with which by the coverages of the star by the planet periodic brightness sinkings of the star are caused, if the orbit soit lies that the planet by-pulls seen from us exactly before the star. Another method is the radial velocity method, with that the planet by its force of gravity influence at the star pulls (both circle around the common emphasis) and thus from thatEarth out this periodic movement an alternating blue shift and red shift (Doppler effect) of the spectrum of the star causes.

To 10. September 2004 communicated the European Southern Observatory that with 225 light-years removed a direct admission of a planet possibly for the first time Succeeded to brown dwarf 2M1207. To 30. April 2005 reported the ESO, in February and March 2005 with the Very Large Telescope taken up photos showed together with the older photographs that itself 2M1207 and its companion, by the force of gravity togetherbound, actually together moved. This can be rated as voucher for the fact that actually the first photographic proof of a Exoplaneten succeeded.

characteristic formulas

• middle subjects close: <math> \ bar {\ rho} = \ frac {m} {\ frac {4} {3} \ pi R^3}< /math>, whereby m = planet mass, R= radius; (<math> \ bar {\ rho} \ geq 3 \ frac {g} {cm^3}< /math> gesteinig, <math> \ bar {\ rho} \ leq 2 \ frac {g} {cm^3}< /math> gas-like)
• circular path speed of v _k around the planet: <math> v_k= \ {\ frac {G m sqrt} {R}}< /math>, whereby G = gravitation constant, m, R like above
• escape velocity v _e: <math> v_e= \ sqrt {2} \ cdot v_k = \ {\ frac {2G m sqrt} {R}}< /math>, howG, m, R like above

other

contrary to the astronomy does not regard the Astrologie also the sun as one „planets “, the earth against it.

The English composer Gustav gets, even, wrote the symphonische Suite to hobby astronomer „The planets “. It belongs to the most well-known Programmmusiken. The individual titles orient themselves at astrological planet symbols, for example „Mars, the intermediary of the war “or „Neptun, Mysti “.

The project Aerovita.net continued to itself dare still another step andused among other things the planets like also the sun and their respective sound, in order to knock a new way into the music.

see also

• to table of the characteristics of the planets
• Titius Bode row
• astronomical objects
• astronomy
• cosmology
• universe
• galaxy

literature

• the time: Expenditure of the 1. August 2005: Transpluto wants into the exclusive solar system planet club: January Osterkamp: Article in on-line offer of the newspaper available: http://apollo.zeit.de/wo/article.php?id=784848
• Peter Janle: The picture of the planet system in the change of the time. Part 1: OfAntiquity up to the center 19. Century. Stars and space 45 (1), S. 34 - 44 (2006), ISSN 0039-1263
• Peter Janle: The picture of the planet system in the change of the time. Part 2: Of 19. Century until today. Stars and space45 (4), S. 22 - 33 (2006), ISSN 0039-1263

Web on the left of

• the nine planets - Multimedia route by the solar system
• RPIF image library
• information to all planets of the solar system, as well as their moons and about all specially-solar planets
• of current and generally comprehensible new type character toPlanet research
• information over Sedna, 2004 DW, Quaoar and 2003 PRACTICE ₃₁₃ - California institutes OF Technology
• “planet search Project” (University OF California) - located most Exoplaneten
• wissenschaft.de: „Were once nine planets… “articles of 22. September 2005itself on Nature - publication refers

videos

• material video Streams: (From the television broadcast alpha Centauri)
  • as gas planets develop?
  • There are 10. Planet?
  • Are the planet courses stable?
  • Are there specially-solar planets?

Wiktionary: Planet - word origin,Synonymous one and translations