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 |  planets  8 planets of the solar system (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune) and their satellites. |  sun The Sun is in 2/3 of the galactic center towards the edge, at a distance of 30 000 light years of the center. The Sun moves in a speed of 230 km/s around this galactic center during its revolution which it makes in 250 million years. |  galaxies The Galaxy, it is the name datum in our galaxy, it is an enormous spiral wheel of stars, a diameter of 100 000 light years. What appears of the Earth, it is a white continuous band called the Milky Way. |  bigbang There is 15 billion years a tremendous explosion of light gives birth to the space, in time, in the matter, a chaos burning with an inconceivable heat, a formless porridge which is going to swell, to extend in all the directions and to cool quite slowly. |  quotations Some quotations of big men (Aristote, Galilee, Newton, Platon, Laplace, Einstein). |  links Some external links concerning the astronomy.

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|  |  dwarf planets According to the definition which was approved on August 24th, 2006, during the 26th General assembly of the UAI ( International Astronomical Union), three bodies reach the status of dwarfish planet: Pluto, eris, and Ceres. Others objets should soon join this nomenclature. |  solar system The solar system is really much more complex if we take into account all the objects being a part of the system. A considerable number of objects is in the belt of Kuiper and still beyond in the cloud of Oort. |  galaxy groups Heap of galaxies are the biggest structures of the Universe. They are constituted by hundreds of galaxies connected together by their own gravitational attraction. Between the galaxies we find some material constituted by warm gas there, forming a plasma, the temperature of which reaches 10 to 100 million degrees. |  comets Besides planets, satellites and asteroids, the solar system contains comets (hair in Greek). The roaming comets originate in the depths of the space in several lights years. The number of periodic comets is of the order of 2000. |  biographies Some biographies, Einstein, Baade, Lyot, Hale, Hubble, Shapley, Laplace, Maxwell, Newton, Herschel, Kepler, Galilee, Aristotle... |  glossary Definition of certain words or expressions used on this site in link with the astronomy.

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| articles Christian's articles in link with the astronomy (history of the Earth, the electron, the neutrons stars, the rings of Saturn, the particles, the threat of asteroids, journey in the universe up to the atom)... |  exoplanets Exoplanets are situated by definition outside our solar system. Seen the large number of existing galaxies and the large number of stars which they contain, the search for these exo-planets or extra solar planets, is unlimited. |  constellations A constellation is a group of stars of the sky which enough close relations looked the appearance imagination of a figure onto the sky. |  nebulas Of the Latin 'nebula' which wants to say cloud, clouds of gas and dusts in the middle of stars, nebulas are at the same moment active crèches and cemeteries of stars. These magnificence of the sky are lit by the stars which they contain or by stars situated behind them. |  telescopes A telescope is constituted by a mirror which concentrates the light resulting from the observed celestial body and from the objective which supplies an enlarged image with it. The increase and the luminosity are proportional on the surface of the mirror. The presence of the ground atmosphere limits the performances of a telescope. It is to mitigate this inconvenience that spatial telescopes were placed in the space. |  bibliographies Some interesting books in link with the astronomy. |  faq Some simple answers concerning the universe which surrounds us.

 |

| asteroids Numerous small rocky called bodies asteroids are present in the solar system, an important part of them circulate in a ring, between the orbit of Mars and that of Jupiter in 2 to 4 UA.

 |  rings The rings of Saturn are one of more beautiful and of the most surprising spectacles of the solar system. That is why on July 1st, 2004, the spaceship Cassini-Huygens reduced its speed to be captured by the gravity of Saturn to enter in orbit with this one. |  stars A star is a celestial body similar to the Sun, which shines thanks to nuclear reactions which occur in its center. |  multiverse The universe is an expanding cosmic bubble. This bubble creates a new bubble which produces it the others etc.... Quantities of the other universes which give birth to the other universes, it is an interesting idea but which remain at the moment very speculative. |  space probes These instruments that are space probes, perceive in the detail the forms and the composition of objects of the distant regions and offer us exceptional sights of an unequalled precision. |  elements The most usual and practical presentation of the diverse chemical elements is the periodic board of elements also called Table of Mendeleyev. The atoms which have the same number of protons but a number different from neutrons are called isotopes. |  aurora A polar aurora called aurora borealis in the north hemisphere and the aurora australis in the southern hemisphere, is a brilliant phenomenon characterized by sorts of veils extremely colored in the night-sky.

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 The universe is all worked up Imprimer cette page


Dwarf planets

      

         
automatic translator        
Definition      

category : planet
       

"A planet is a celestial body which is on orbit around the Sun, which possesses a sufficient mass so that its gravity takes it on the strengths of cohesion of the solid body and maintains it in hydrostatic equilibrium (spherical shape), and which eliminated any body moving on a close orbit ".
This definition was approved on August 24th, 2006, during the 26th General assembly of the UAI (International Astronomical Union) by a vote by a show of hands about 400 scientists and astronomers after ten days of discussions. In addition, the UAI created a new class of objects: the dwarf planets.

  

A dwarf planet, since the new definition of August, 2006, is a celestial body on orbit around the Sun:
- witch has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (near-spherical) shape,
- witch has not cleared the neighborhood around its orbit.
- witch is not a satellite
According to this last one, three bodies reach the status of dwarf planet: Pluto, Eris, and Ceres. Other bodies should soon join this nomenclature.

  
Objects Diameter (km)
Easter Bunny 1300 x 1900
Orcus 840 x 1880
Sedna 1180 – 1800
Santa ~ 1960×1518×996
Quaoar 989 x 1346
Charon 1207
2002 TC302 ≤ 1200
Varuna ~ 936
2002 UX25 ~ 910
2002 TX300 < 900
Ixion < 822
2002 AW197 700 ± 50
         

Pluto

      

category : planet
       

Pluto Discovered in 1930 by the American astronomer Clyde Tombaugh, Pluto is out of the ordinary. Of an equatorial diameter lower than 2 500 km, it represents only tenth two of the Earth. Not satisfied to be, so far, the smallest member of the solar system, it also possesses an eccentric and very oblique orbit with regard to the plan of the ecliptic.  was discovered in 1930 during the search for a celestial body allowing to explain the orbitales disturbances of Uranus and Neptune, hypothesis proposed by Percival Lowell as being the Planet X. Pluto possesses a satellite, Charon, discovered by James Christy in 1978, is a big satellite with regard to the planet mother (diameter 1270 km). Charon has a mass about ten times lower than Pluto and the report of diameters is from 1 to 2.

  

PLUTON.jpg (8940 octets)

  
Pluto  
diameter 2306±20 km
surface 17 millions km²
mass 1,314±0,018×1022 kg
gravity 0,655 m/s²
inclination of the axis 119,61°
albedo 0,60
escape velocity 1,3 km/s
absolute magnitude  
rotation period  
surface temperature 33 K à 55 K
         

Eris

      

category : planet
       

Eris The object 2003UB313, is officially appointed by the international astronomical Union in August, 2006. The name chooses is that of the Greek goddess Eris. In the Greek mythology, Eris is the goddess of the Discord. According to Hésiode, she is a girl of Nyx (the Night) and a mother of the Pain, the Famine and the other plagues  was photographed for the first time during made observations in October 21st, 2003 with the telescope Oschin of 1,22 meters of the Mountain Palomar, in California, by the team of Caltech was photographed for the first time during observations made which had already discovered several big beyond Neptune objects as (50000) Quaoar and (90377) Sedna.
Thanks to the spatial telescope Hubble and to that of the W.M. Keck Observatory the measure of the mass of Eris, the biggest member of the class of dwarfish planets in our Solar system, was able to be realized. Eris is 1,27 times as massive as Pluto, formerly the biggest member of the Belt of Kuiper of the ice-cold objects revolving beyond the orbit of Neptune.

  

 
Eris  
diameter 2 400 km ± 100 km
surface  
mass 1,668×1022 kg
gravity  
inclination of the axis  
albedo 0,6 
liberation speed  
absolute magnitude -1,2
rotation period  
surface temperature ~ 30 K
         

Cérès

      

category : planet
       

Ceres Ceres is the first bare asteroid. We recognize him the definition of dwarfish planet today, since the new definition of the international astronomical Union of August, 2006. With about a diameter 950 km, Ceres is also the biggest member of the belt of asteroids situated between the orbits of Mars and Jupiter was accidentally discovered. Piazzi tried to observe a star listed by Francis Wollaston under the name of Mayer 87 because she was not in the position given in the zodiacal catalog of Mayer (it turned out afterward that it was in fact about Lacaille 87). On the place, he observed an object moving on the sky, that he believed at first to be a comet.

  

 
Ceres  
diameter 959,2×932,6 km
surface  
mass 9,445×1020 kg
gravity 0,26 m/s²
inclination of the axis  
albedo 0,113
liberation speed 0,51 km/s
absolute magnitude 3,34
rotation period 0,3781 d
surface temperature ~167 K
         

Sedna

      

category : planet
       

Sedna Sedna (Goddess Inuit of the ice-cold oceans of the north pole), is the biggest beyond Neptune object after Pluto and Eris.   Situated in an almost empty space, Sedna is more red and more brilliant than any object of the solar system. The scientists have not determined the reason of these unique characteristics yet. He could possess the small moon. In April, 2005 a more precise measure of the celestial body allowed to determine a complete rotation speed about 10 hours. At the time of its discovery, Sedna was the biggest object discovered in the solar system since the discovery of Pluto. Bigger objects (dwarf planets) were since discovered, as Eris.

  

 
Sedna  
diameter 1180×1800 km
surface  
mass 1.7-6.1×1021 kg
gravity  
inclination of the axis 11,934°
albedo 0,2
liberation speed 0,62-0,95 km/s
absolute magnitude 1,6
rotation period 0,42 d
surface temperature ~33 K
         

Related subjects

      

category : planet
       

Mercury

  

Jupiter

  

dwarf planets

Venus

  

Saturn

  

Eris

Terre

  

Uranus

  

Sedna

Mars

  

Neptune

  

Quaoar
       

Pluto
       

Ceres
         

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 |  planets  8 planets of the solar system (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune) and their satellites. |  sun The Sun is in 2/3 of the galactic center towards the edge, at a distance of 30 000 light years of the center. The Sun moves in a speed of 230 km/s around this galactic center during its revolution which it makes in 250 million years. |  galaxies The Galaxy, it is the name datum in our galaxy, it is an enormous spiral wheel of stars, a diameter of 100 000 light years. What appears of the Earth, it is a white continuous band called the Milky Way. |  bigbang There is 15 billion years a tremendous explosion of light gives birth to the space, in time, in the matter, a chaos burning with an inconceivable heat, a formless porridge which is going to swell, to extend in all the directions and to cool quite slowly. |  quotations Some quotations of big men (Aristote, Galilee, Newton, Platon, Laplace, Einstein). |  links Some external links concerning the astronomy.

|
|  |  dwarf planets According to the definition which was approved on August 24th, 2006, during the 26th General assembly of the UAI ( International Astronomical Union), three bodies reach the status of dwarfish planet: Pluto, eris, and Ceres. Others objets should soon join this nomenclature. |  solar system The solar system is really much more complex if we take into account all the objects being a part of the system. A considerable number of objects is in the belt of Kuiper and still beyond in the cloud of Oort. |  galaxy groups Heap of galaxies are the biggest structures of the Universe. They are constituted by hundreds of galaxies connected together by their own gravitational attraction. Between the galaxies we find some material constituted by warm gas there, forming a plasma, the temperature of which reaches 10 to 100 million degrees. |  comets Besides planets, satellites and asteroids, the solar system contains comets (hair in Greek). The roaming comets originate in the depths of the space in several lights years. The number of periodic comets is of the order of 2000. |  biographies Some biographies, Einstein, Baade, Lyot, Hale, Hubble, Shapley, Laplace, Maxwell, Newton, Herschel, Kepler, Galilee, Aristotle... |  glossary Definition of certain words or expressions used on this site in link with the astronomy.

 |
| articles Christian's articles in link with the astronomy (history of the Earth, the electron, the neutrons stars, the rings of Saturn, the particles, the threat of asteroids, journey in the universe up to the atom)... |  exoplanets Exoplanets are situated by definition outside our solar system. Seen the large number of existing galaxies and the large number of stars which they contain, the search for these exo-planets or extra solar planets, is unlimited. |  constellations A constellation is a group of stars of the sky which enough close relations looked the appearance imagination of a figure onto the sky. |  nebulas Of the Latin 'nebula' which wants to say cloud, clouds of gas and dusts in the middle of stars, nebulas are at the same moment active crèches and cemeteries of stars. These magnificence of the sky are lit by the stars which they contain or by stars situated behind them. |  telescopes A telescope is constituted by a mirror which concentrates the light resulting from the observed celestial body and from the objective which supplies an enlarged image with it. The increase and the luminosity are proportional on the surface of the mirror. The presence of the ground atmosphere limits the performances of a telescope. It is to mitigate this inconvenience that spatial telescopes were placed in the space. |  bibliographies Some interesting books in link with the astronomy. |  faq Some simple answers concerning the universe which surrounds us.

 |

| asteroids Numerous small rocky called bodies asteroids are present in the solar system, an important part of them circulate in a ring, between the orbit of Mars and that of Jupiter in 2 to 4 UA.

 |  rings The rings of Saturn are one of more beautiful and of the most surprising spectacles of the solar system. That is why on July 1st, 2004, the spaceship Cassini-Huygens reduced its speed to be captured by the gravity of Saturn to enter in orbit with this one. |  stars A star is a celestial body similar to the Sun, which shines thanks to nuclear reactions which occur in its center. |  multiverse The universe is an expanding cosmic bubble. This bubble creates a new bubble which produces it the others etc.... Quantities of the other universes which give birth to the other universes, it is an interesting idea but which remain at the moment very speculative. |  space probes These instruments that are space probes, perceive in the detail the forms and the composition of objects of the distant regions and offer us exceptional sights of an unequalled precision. |  elements The most usual and practical presentation of the diverse chemical elements is the periodic board of elements also called Table of Mendeleyev. The atoms which have the same number of protons but a number different from neutrons are called isotopes. |  aurora A polar aurora called aurora borealis in the north hemisphere and the aurora australis in the southern hemisphere, is a brilliant phenomenon characterized by sorts of veils extremely colored in the night-sky.

|
 The universe is all worked up Imprimer cette page


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Astronomy - october 15th 2007