Rhea (moon of Saturn)


\|	\| 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

Rhea

automatic translator

Rhea moon of Saturn

category : satellites of planets

Rhea is the second moon of Saturn by the size after Titan. It was discovered in 1672 by Giovanni Domenico Cassini. Rhea was glanced through for the first time to Travel 1 in November, 1980. The Cassini probe is crossed in November 26th, 2005, in 500 km above its surface. Rhea is an ice-cold body of weak density (1240 kg / m3), indicating that the moon consists of a rocky nucleus counting only for a third of the mass of Rhea, the rest being mainly some ice-cold water. The temperature on the surface of Rhea is of-174°C in the sun, and of-200°C in-220°C in the shadow. In orbit synchronous around Saturn, Rhea always presents the same hemisphere to Saturn. The space probe Cassini presents us here the "back" face of Rhea. The hemisphere before is strongly craterised and uniformly clearly. As Callisto, craters lack structures in the marked relief presents on the Moon and the Mercury. The back hemisphere presents a network of clear trails on a dark bottom, and few craters. These trails could be the matter ejected by volcanoes of ice while Rhea was still liquid under the surface.

Rhea		moon of Saturn
diameter		1528 km
mass		2,32×10²¹ kg
discovery		23 December 1672
discovery by		Jean-Dominique Cassini
semi major axis		527 100 km
density		1240 kg/m3
temperature		53 K à 99 K -174°C à -220°C

Image taken with the telephoto lens of the probe Cassini on January 17th, 2007 at a distance about 597000 kilometers of Rhea. The resolution is 4 kilometers by pixel.

The universe of Rhea

category : satellites of planets

In the Greek mythology, Rhea, Rheia or Rhee was Titanide, a girl of Ouranos ( the Sky) and Gaia the Earth), sister and woman of the Titan Cronos, and the mother of the gods Hestia, Demeter, Hera, Hades, Poseidon and Zeus.
With its 1 528 kilometers in diameters, Rhea appears here as a quite small grey and ice-cold object which contrasts with colors pastel of the huge planet, the Saturn. Let us imagine ourselves the sight of Saturn since Rhea. Rhea is 1528 km in diameter and Saturn 120 536 km in diameter. Rhea is situated in 527 100 km of Saturn, what is very close for this small object. Let us come back to earth and let us imagine that we have a celestial body also near and while keeping the same proportions it would mean observing in the sky a gigantic object 100 times as big as the Moon what would hide an enormous part of the sky.

This image taken by means of the red, green and blue filters was combined to produce this sight in natural color. The pictures were realized with the camera wide-angle lens of the space probe Cassini on February 4th, 2007 at a distance of 1,2 million kilometers of Saturn and at 679 000 kilometers of Rhea. The resolution is 68 kilometers by pixel on Saturn and about 40 kilometers by pixel on Rhea. This sight is taken since the side not lit by rings in approximately 3 degrees over their plan and their shadow is visible at the top to the right of the image.

Related subjects

category : satellites of saturn

Dione

Titan


\|	\| 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

Astronomy - october 15th 2007