After the solid state ... the gas!

After the rocky planets and the asteroid belt we find the planets called " Giant gaseous",

 Jupiter and Saturn.

They are followed by "Ice Giant", for Uranus and Neptune.

Their diameter ranges from 49,922 to 142,984km!

A great bubble ...

Jupiter is the first giant planet starting from the sun.

 It is also the largest planet in the solars System with an average diameter of 142,984km.



It can thus contain more than 1300 times the Earth.

Its atmosphere is mainly composed of gas86 % dihydrogen and helium about 13 %.


 The planet does not have a solid surface.

It is permanently encircled by cloud bands with strong winds.

The " Great Red Spot " is particularly an anticyclonic storm that has been raging for over 300 years.



The existence of a solid nucleus at the center of Jupiter is probable, and its temperature could exceed 20 000degree C.




 The latter is surrounded by a layer undergoing the effects of heat and pressure.





Liquid atomic hydrogen is present in metallic form, and swirling currents cause a gigantic magnetic field.




Then comes a layer of liquid atomic hydrogen, situated beneath the cloud layer of Jupiter, where the increasing pressure leads this element to assume a liquid rather than a gaseous state.



The atmosphere, composed largely of dihydrogen gasH2 ) and a little heliumHe), extends upwards for nearly 5000km until it melts into interplanetary space.




 Thick clouds form strips of different colors that exhibit alternating circulations.





In addition, the winds are very violent and frequently reach the speed of 360 km/h.





Jupiter is also surrounded by a system of thin and diffuse rings, made up of dust, which are difficult to detect.




The gravitational pull of Jupiter is strong enough to attract a large number of orbiting satellites.





To date, 67 satellites are known, but only of them are the size of a planet and dominate the Jovian System.




These four immense Galilean satellites areLo, which has a volcanic activity; Europe, which has an icy surface.





Ganymede, which has a past geological activity, and finally Callisto, which has a crater-riddled soil.




In addition, the last three would have an océan of liquid water under a layer of ice.

Ganymede is the largest satellite of the Solar System with 5262km in diameter.




By defining the Earth/Sun distance as the Astronomical Unit, the average Jupiter/Sun distance is 5.20 AU, or 778.6million km.



The inclination of its axis of rotation is 3.1degrees.

Its rotation period is 9h55min.

Its period of revolution around the sun is 11.86 terrestrial years, or 4331 earth days.



To date, 67 natural satellites have been counted around the planet Jupiter.

The planet Jupiter has 67 known moons, pay attention to the tides!

Silence, its turning ...

The planet Saturn is the second giant planet starting from the sun and the second largest planet of the solar system after Jupiter.



The planet Saturn is mainly composed of 2gases and does not have a real solid surface.




In volume, 96 hydrogen ( H2 ), 3 % helium ( He ), and 1 % other elements.

Its density is very low, so much so that it could float if it were to dive into the water.



The nucleus of Saturn is probably composed of a mixture of rock and molten metal, with a temperature of more than 11700 ° C and a diameter of about 25000km.




This nucleus is surrounded by liquidmetallic hydrogen, where hydrogen is in atomic form, 




creating an ocean of electrically conductive liquid metal with currents that generate the powerful magneticfield of Saturn.




Next comes a layer of liquid hydrogen up to 6000degree C, which comes from a gradual condensation of molecular hydrogen ( H2).



The last layer corresponds to the atmosphere, mainly composed of dihydrogen gas and helium, and scattered with clouds formed from the condensation of various chemical compounds, including ammonia and water.


Winds can reach 1800 km/h.The planet Saturn is also surrounded by the largest ring formation of the Solar System, more than 270,000km diameter for the ring A.


  Its thickness is about 1km but can locally be reduced to a few tens of meters.

They contain billions of pieces of water ice,

And each large ring is composed of many small narrow rings.


 The principal rings are separated by divisions composed of dark matter.

The main divisions are created by resonanceeffects with more distant satellites.




62 satellites are officially recognized and form the Saturnian system.




Among them, 7 satellites are large enough so that gravity has given them a spherical shape: MimasEnceladus, TethysDione, Rhea, Titan and Iapet.




Titan is in particular the only satellite of the solar system with a dense atmosphereconsisting mainly of diazote and a little methane.



  It has a complex climate cycle, with methane and ethane in the liquid phase evaporating and falling in the form of rain.




The surface is composed mainly of ice, and its average temperature is -179 degree C.




 With a diameter of 5150 km, it is also the largest of Saturn satellites, gravitatingat a distance of 1.2 million miles in an orbit traveled in 15 days and 22 hours.



 The average distance of the sun is 9.54UA 1 billion and 430 million km, with an inclination of the axis of rotation of 26.7degree.



The planet Saturn has a rotation period of 10h39mn and a period of revolution around the sun of 29.46 terrestrial years, that is 10747 terrestrial days.



The temperature at the top of the clouds is  -140degre C.

The planet Saturn has 62 known moons to date, and hundreds of mini-moons about 1km.

After the gas ... the ice!

The Universe declines its "states of soul"solid, liquid and gaseous...

The Planet Uranus

The planet Uranus is the 7th planet starting from the sun, and the 3rd largest of the solar system.




It is four times larger than Earth.

It is also the coldest planet with Neptune, with a blue-green color coming from the presence of methane.

 It is part of the 4 giant planets, but enters the subcategory of giants of ice with Neptune 



Its atmosphere is composed mainly of hydrogen(83 %) and helium (15 %), followed by methane(2 %) and ammonia (0.001 %).



 Its axis of rotation is inclined by more than 90 degrees so that the planet "rolls" in its orbit, presenting one of its poles to the sun for 42 years.




The nucleus of Uranus would be composed of rocks rich in silicates and iron-nickel of the size of the Earth.




It would be surrounded by a mantle of ice, ammonia and methane.

Then comes the atmosphere, consisting mainly of hydrogen and helium, with strata of clouds at different altitudes.



Uranus is also surrounded by very dark banks, composed of rocks and dust.




Observations of Voyager 2, the Hubble Space Telescope and astronomers from the Earth allowed the 27 known satellites of the Uranus system to be identified.



The two largest satellites are Titania and Oberon with a size greater than 1500km.

Titania is the largest satellite of Uranus and the 8th largest of the solar system.



 It possesses gigantic gorges and cliffs, and a possible very fine atmosphere composed of carbon dioxide.




Oberon consists of a mixture of ice and rock, with a dark reddish surface.




The average Sun distance to Uranus is 19.2 AU, or 2872.5 million km, with an inclination of the axis of rotation of 97.8degrees.




The planet Uranus has a retrograde periodof 17h 14 min, and a period of révolution around the sun of 84.02 terrestrial years, that is to say 30687 terrestrial days.



The temperature at the top of the cloud would be of -220 degree C.

The planet Uranus have 27 listed moons and

13 rings!

And in number 8 ...

Neptune is the eighth planet from the Solar  system.

Its blue color comes from the methanecontained in its atmosphere.



It is a giant icy planet, composed mainly of gas and ice.

It is inclined at an angle similar to that of the Earth,



 which allows it to also have a seasonal rhythm during its revolution, although in the case of Neptune, each season lasts more than forty years!




The nucleus of Neptune would be composed of silicates and iron, and probably possesses a central temperature above 5000degree C.


  The latter is undoubtedly bathing in an oceanof liquid diamond.

It would be surrounded by a mantle, consisting of ice waterammonia and methane at high temperature and fluid.



It contains a thin layer of electrically charged liquids, which is probably at the origin of Neptune's magnetic field.




Then comes the atmosphere, formed of hydrogen, helium and traces of methane.

There are thick clouds, agitated by often violent winds up to 2200 km/h, and thunderstorms!



Neptune is also surrounded by 5 rings very thin and rather dark, formed of dust whose composition is unknown.



The farthest, Adams, is actually made up of arcs which were named CourageLibertéEgalité and Fraternitébecause their discovery was obtained by a French team.




Observations from the Voyager 2 probe and ground-based telescopes identified 14 satellites.





The largest of these, Triton, has a diameter of 2700 km and represents 99.7 % of the total mass of this system.




It revolves around Neptune in the retrograde sense.

It seems that it is an object of the Kuiper belt captured by the planet.




Moreover, its trajectory is not stable due to tidal effects.





It slowly follows a spiral trajectory to Neptune and should dislocate when it reaches the Roche Limit.




Edouard Roche is a French astronomer of the 19th century who predicted that within a certain distance to a planettidal effectsdid not allow the existence of satellites.



 It is at a distance below this limit that the rings of the giant planets that can not agglomerate in satellites are found.



 The planet Neptune has an average sundistance of 30.1 AU, or 4504 million km, and an inclination of the axis of rotationof 28.32 degrees.




 Its rotation period is 16h06 min, and a period of revolution around the sun of 164.8 terrestrial years, or 60 182 terrestrial days.




The temperature at the pressure of 0.1 bar is -218 degrees C, ie 55 kelvin.

So the leather jacket, forget it!

After the giant .... the dwarfs!

Beyond the planet Neptune lies the belt of Kuiper.

It is a ring-shaped zone in which transneptunians and known dwarf planets evolve, including Pluto, once considered a planet in its own right.

In this area we also find the other dwarf planets as well as many asteroids and short period comets.

In the future, new dwarf planets will certainly be identified in this part of the SolarSystem, rich in objects larger than 100km, which will be added to Haumea, Makémaké and Eris.

And a belt again!

The Kuiper Belt is an area beyond the orbite of Neptune that can be divided into two parts.





The first part is between 30 and 50 AU.

It stops at what is called the "cliff of Kuiper".





It is in this zone that orbit the dwarf planet Pluto.





The second part extends from 50 to a hundred astronomical units.

It includes other dwarf planets such as Eris.





The belt of Kuiper consists of millions of short-period comets; Bodies ranging from the size of a dust grain to several hundred kilometers!




The orbits of these objects are most often eccentric and exhibit a much more pronounced inclination than objects closer to the Sun.




This belt therefore forms a kind of toroïdal ring comprised between 30 and 100 AU.





Solar winds collide with the interstellar medium at about 95 AU, 3 times the distance between the Sun and Pluto.





Here, the contrary pressure of the cosmic rays slows down the solar wind, which condenses and heats up.




 The heliosphere actually has a drop shape with one crushed side and another elongated.

When the solar winds stop, at the limit of the heliosphere, we call it Heliopause!

The Ninth Planet: Pluto!

The planet Pluto was discovered on February 18, 1930 by amateur astronomer Clyde Tombaugh.




It was classified as a planet for 76 years, but on 24 August 2006, the International Astronomical Union classified it as a new planet category: dwarf planets.


 The planet Pluto orbits about 7 billion kilometers but, because of its eccentricity, it is only 4 billion kilometers from the Sun when it is at its perihelion, thus entering the orbit of Neptune.




The planet Pluto makes a revolution around the Sun in 248 years.




It would be formed of a rocky core surrounded by an ice mantle 20km thick.






The planet Pluto has 5 satellites, the first one was discovered on June 22, 1978: it is Charon.





Two others were discovered in 2005, Nix and Hydra.

Kerberos was discovered in 2011 and Styx in 2012.




Charon does not turn around Pluto, but the two "round rocks" revolve around the same center of gravity situated between the two bodies!




 From its Earth orbit, the Hubble Space Telescope can only distinguish the largest details of the Pluto surface.





On July 14, 2015, she was visited by the New Horizons space craft, which was able to photograph the dwarf planet and its satellites.




The probe also made it possible to refine the size of Pluto2370km in diameter, reclassifying it as the biggest dwarf planet just in front of Eris.




Pluto is resonating 3/2 with Neptune.

Indeed, the orbital period of Pluto is exactly 1.5 times longer than that of Neptune.



 Thus, although it seems that the orbit of Pluto crosses that of Neptunethey will never collide.






Like UranusPluto's equatorial plane is almost at right angles to its orbital plane.




The temperature at the surface of Pluto would be not very well known but it is probably between 35 and 45 Kelvin (-228 and  -238degree C).


An asteroid is a minor planet that is composed of rocksmetals and ice, and whose dimensions vary by the order of a meter, which corresponds to their detection limit to several hundred kilometers.


 When their diameter is close to or exceeding 1000 km, which is rare, their shape may be spherical and they may then also assume the status of dwarf planet.



 This is the case with Ceres.

Otherwise, they usually have an irregular shape and are part of the class of small bodies.





Asteroids, called meteorites for the smallest ones entering the atmosphere of another body create meteors.





If a part of the asteroid manages to touch the impacted body surface, it then forms a meteorite and can create a crater impact.





In 1801, the first asteroid is discovered and is named Ceres; It is the largest of the solar system.




Since then, more than 580,000 solar asteroids have been recorded.





The first asteroids discovered have an orbite between those of Mars and Jupiter, so this area is called the main asteroid belt.




Another area beyond the orbit of Neptune has a high concentration of asteroids: the Kuiper belt!





The composition of the asteroids of the Kuiper belt is richer in ice and poorer in metals and rock, which appears like cometary nuclei.




Unlike comets, asteroids are inactive, however some have been observed with cometary activity.





It is assumed that asteroids are remnants of the protoplanetary disk that have not been grouped into planets.




Some asteroids crossing Earth's orbit, called NEOs, are considered potentially hazardous due to the risk of collision and are monitored by automated systems.



Comets are made up of ice and dust.





comet is an almost spherical body that can reach about ten kilometers in diameter.

It consists of ice and dust.

Its name comes from the Greek coma meaning "tail".


 Indeed, when a "dirty snow ball" approaches the Sun, a part of its material sublimates and the star develops a tail of dust, several millions of kilometers long.



 This matter reflected the light of the Sun, which makes the body visible from the Earth, then we speak of comets!




The comets would have formed with the SolarSystem, in its cold regions, 4.6 billion years ago.





In 1950. The astronomer Jan Oort hypothesized the existence of a spherical reservoir of comets located at the edge of the solar system.



 Following gravitational instabilities caused by the movement of nearby stars, certain bodies would fall from time to time on the Sun by describing a parabolic trajectory!




 There are different types of comets.

The non-periodic comets, originating from the cloud of Oort and which passes only once near the Sun.




Other comets are periodic, such as the comet of Halley, and regularly pass near the Sun.





During a passage, they lose a part of their mass and end up by "extinguishing", lack of material to sublimate!





It is found that the life expectancy of a periodic comet is very short compared to the age of the Solar System.





Now we have said that the comets were born at the same time as the sun.

How is it that we still see periodic comets?




Some of the comets from the Oort Cloud can pass close to a planet on their journey around the Sun.





Their trajectory can then be modified and lead to an elliptical orbit and thus to a periodic comet.






This mechanism explains the presence of periodic comets at all times.

Until the clouds ....

The cloud of Hills.

The area between the Kuiper Belt and the Oort Cloud is referred to as Hills Cloud" or "Oort Inner Cloud".




It would be between 100 and 300 AU and would form transition zone between the Kuiper Belt and the Oort Cloud.




The Hills cloud would have a shape closer to that of the Kuiper belt than to that of a spherical cloud like that of Oort.





It would be thiner inward and thicker as one moves away from the Sun.




It would be composed of the same elements as the areas that surround it: comets and dwarf planets still unknown!




The cloud of Oort to conclude?