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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 (Aristotle, Galilee, Newton, Plato, 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 objects 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  Kuiper belt and still beyond in the cloud of Oort. |  heaps 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 years lights. 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 exoplanets 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.

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| 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


Are we alone ?

      

         
Definition of the life      

category: extraterrestrial life
       

The scale of the question does not allow answering simply, if by chance there is an answer. Because this question concerns the philosophic aspect on the one hand and the chemical aspect of the life, on the other hand. We notice that the life evolves in time taking a way defined by infinity of parameters, what makes it indefinable and unpredictable. Nevertheless, there is a biological definition of the life:
"an organism is said in life when it exchanges matter and energy with its environment, by preserving its autonomy, when it reproduces and evolves by natural selection. »

 

All the organisms alive as ensure their stability by reacting to the environment changes. Then, the life has an adaptation and a learning ability. Isn’t rather that the life?
But, we also notice, by observing the galaxies, the stars and the planets that the matter is quite capable to auto-getting organized without being alive for all that. However, a good definition of the life has to take into account this concept, the matter ability to climb gradually the grades of the complexity.

  

We recognize the life when we see it!
         

Are we thus alone?

      category: extraterrestrial life
       
As long as we did not discover an extraterrestrial life, we are effectively alone. Let us take into account the chances which we have to discover a life somewhere else. Since 1995, the astronomers began looking for exoplanets and discovered several hundreds, and it is going to accelerate. Our chances grow every day...
The physical conditions are the same everywhere in the Universe: the galaxies contain stars, stars have gaseous or / and telluric planets, planets are constituted by infinity of chemical elements as hydrogen, carbon, water...
Take only one galaxy among the billions existing, our, the Milky Way. In the Milky Way, there are 100 to 300 billion stars, what produce a considerable number of planets.
Even if the necessary conditions to the emergence of the life are difficult to combine, the number of existing planets allows us to think that the life develops or develops probably somewhere else. The astronomy progresses are going to show that the favorable sites and conditions to the life are universals, and that, the chemistry of the carbon (at the origin of the life) meets itself everywhere in the Universe.
Today, we haven’t any formal proofs of 		 

this other life, but I think that it must have a large number of places where the life abounds, from the primary state to the advanced state as our and certainly beyond. At present, our imagination is blocked by our egocentric vision of the world, which persuades us that the humanity is the unique and extraordinary product of the intelligence, but the given time to the evolution is infinite.
The life needs time to reach the complexity, and it is the result of an adaptation pressure to the environment. This pressure engenders the fact that living cells are what they are at a moment: the result of millions of different random phenomena (meteorite impacts, global cataclysms) which modify the evolution road towards the complexity. These phenomena are real contingencies that the chronology is almost impossible to reproduce. What makes say to certain astronomers that the life on Earth is unique. It is sure that it is unique seemingly, we will not discover the other men somewhere else, but the life seems to be strength, present in the Universe, as   contingencies the contingency is the negation of the necessity. A proposition is the contingent if it is not necessary (she could be false). Situation where the state of a system is determined by the value of independent, even contradictory internal and external parameters.  the strength of gravitation, the electromagnetic strength, the strong nuclear strength and the weak nuclear strength (see the article of the big bang). (see the article on the big bang)

  

The proof of the extraterrestrial life can arrive in one minute or in several million years but the life on Earth has 5 billion years in front of and the present intelligence on Earth at this moment there will see these other lives.

         

Related subjects

       category: extraterrestrial life
       
Les exoplanètes        
Multivers        
Big bang        

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 |  planètes  Les 8 planètes du système solaire (Mercure, Vénus, Terre, Mars, Jupiter, Saturne, Uranus, Neptune) et leurs satellites. |  soleil Le Soleil est au 2/3 du centre galactique vers le bord, à une distance de 30 000 années-lumière du centre. Le Soleil se déplace à une vitesse de 230 km/s autour de ce centre galactique pendant sa révolution qu´il effectue en 250 millions d´années. |  galaxies La Galaxie, c´est le nom donnée à notre galaxie, c´est une énorme roue spirale d´étoiles, d´un diamètre de 100 000 années-lumière. Ce qui apparaît de la Terre, c´est une bande blanche continue appelée la Voie Lactée. |  big bang Il y a 15 milliards d´années une formidable explosion de lumière donne naissance à l´espace, au temps, à la matière, un chaos brûlant d´une chaleur inimaginable, une bouillie informe qui va enfler, s´étendre dans toutes les directions et se refroidir tout doucement. |  citations Quelques citations de grands hommes (Aristote, Galilée, Newton, Platon, Laplace, Einstein, ...). |  liens Quelques liens externes concernant l´astronomie.

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|  |  planètes naines Selon la définition qui fut approuvée le 24 août 2006, lors de la 26e Assemblée Générale de l´UAI (Union Astronomique Internationale), trois corps accèdent au statut de planète naine : Pluton, éris, et Cérès. D´autres corps devraient prochainement rejoindre cette nomenclature. |  système solaire Le système solaire est en réalité beaucoup plus complexe si l´on prend en compte tous les objets faisant partie du système. Un nombre considérable d´objets sont dans la ceinture de Kuiper et encore au delà dans le nuage de Oort. |  amas Les amas de galaxies sont les plus grandes structures de l´Univers. Ils sont constitués de centaines de galaxies liées ensemble par leur propre attraction gravitationnelle. Entre les galaxies on y trouve de la matière constituée de gaz chaud, formant un plasma, dont la température atteint 10 à 100 millions de degrés. |  comètes Outres les planètes, satellites et astéroïdes, le système solaire contient des comètes (chevelure en grec). Les comètes vagabondes prennent naissance au plus profond de l´espace à plusieurs années lumières du Soleil. Le nombre de comètes périodiques est de l´ordre de 2000. |  biographies Quelques biographies, Einstein, Baade, Lyot, Hale, Hubble, Shapley, Laplace, Maxwell, Newton, Herschel, Kepler, Galilée, Aristote, ... |  glossaire Définition de certains mots ou expressions utilisés sur ce site en lien avec l´astronomie.

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| articles Articles de Christian en lien avec l´astronomie (histoire de la Terre, l´électron, les étoiles à neutrons, les anneaux de Saturne, les particules, la menace des astéroïdes, voyage dans l´univers jusqu´à l´atome, ...). |  exoplanètes Les exoplanètes sont par définition situées hors de notre système solaire. Vu le grand nombre de galaxies existantes et le grand nombre d´étoiles qu´elles contiennent, la recherche de ces exo-planètes ou planètes extrasolaires, est sans fin. |  constellations Une constellation est un groupe d´étoiles de la voûte céleste qui suffisamment proches ont données l´apparence imaginaires d´une figure sur la voûte céleste. |  nébuleuses Du latin ´nebula´ qui veut dire nuage, nuages de gaz et de poussières au milieu des étoiles, les nébuleuses sont à la fois des pouponnières actives et des cimetières d´étoiles. Ces splendeurs du ciel sont éclairées par les étoiles qu´elles contiennent ou par les étoiles situées derrière elles. |  télescopes Un télescope est constitué d´un miroir qui concentre la lumière provenant de l´astre observé et d´un objectif qui en fournit une image agrandie. L´agrandissement et la luminosité sont proportionnels à la surface du miroir. La présence de l´ atmosphère terrestre limite les performances d´un télescope. C´est pour pallier cet inconvénient que des télescopes spatiaux ont été placés dans l´espace. |  bibliographies Quelques livres intéressants en lien avec l´astronomie. |  faq Quelques réponses simples concernant l´univers qui nous entoure.

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| astéroïdes De nombreux petits corps rocheux appelés astéroïdes sont présents dans le système solaire, une partie importante d´entre eux circulent dans un anneau, entre l´orbite de Mars et celle de Jupiter à 2 à 4 UA.

 |  anneaux Les anneaux de Saturne sont un des plus beaux et des plus étonnants spectacles du système solaire. C´est pourquoi le 1er juillet 2004, le vaisseau spatial Cassini-Huygens a réduit sa vitesse pour être capturé par la gravité de Saturne afin d´entrer en orbite avec celle-ci. |  étoiles Une étoile est un astre semblable au Soleil, qui brille grâce à des réactions nucléaires qui se produisent en son centre. |  multivers L´univers est une bulle cosmique en expansion. Cette bulle crée une nouvelle bulle qui en produit d´autres etc ... Des quantités d´autres univers qui donnent naissance à d´autres univers, c´est une idée intéressante mais qui reste pour l´instant très spéculative. |  sondes Ces instruments que sont les sondes spatiales, perçoivent dans le détail les formes et la composition d´objets des régions lointaines et nous offrent des vues exceptionnelles d´une précision inégalée. |  les éléments La présentation la plus usuelle et pratique des divers éléments chimiques est le tableau périodique des éléments également appelé Table de Mendeleïev. Les atomes qui ont le même nombre de protons mais un nombre différents de neutrons sont appelés des isotopes. |  aurores Une aurore polaire appelée aurore boréale dans l´hémisphère nord et aurore australe dans l´hémisphère sud, est un phénomène lumineux caractérisé par des sortes de voiles extrêmement colorés dans le ciel nocturne.

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Astronomy - 31 oct. 2007