Rotation d'Ariel, satellite d'Uranus

Caractéristiques d'Ariel

Type
Satellite naturel d'Uranus
Demi-grand axe
190 900 km
Excentricité
0,0012
Période de révolution
2,520 d
Inclinaison
0,041°
Dimensions
1162×1156×1155 km
Masse
1,4×1021 kg
Masse volumique moyenne
1,7×103 kg/m³
Gravité à la surface
0,27 m/s²
Période de rotation
Synchrone
Albédo moyen
0,39
Température de surface
~80 K
Pression atmosphérique
Pas d'atmosphère
Découverte
William Lassell le 24 octobre 1851

Ariel (U I Ariel) est le quatrième plus grand satellite d'Uranus. Il fut découvert en 1851 par William Lassell.

Composition d'Ariel - Lune d'Uranus

Ariel serait composé à 50% de glace d'eau, à 30% de silicates et à 20% de glace de méthane(CH4) et il semble que certaines régions de sa surface aient été récemment gelées. Largement dépourvu de cratères d'impact, Ariel semble avoir subi une période d'intense activité géologique qui a produit un réseau complexe de canyons et d'écoulement d'eau liquide à sa surface.

<h1>PIA01356: Ariel's transecting valleys</h1><div class="PIA01356" lang="en" style="width:512px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This highest-resolution Voyager 2 view of Ariel's terminator shows a complex array of transecting valleys with super-imposed impact craters. Voyager obtained this clear-filter, narrow-angle view from a distance of 130,000 kilometers (80,000 miles) and with a resolution of about 2.4 km (1.5 mi). Particularly striking to Voyager scientists is the fact that the faults that bound the linear valleys are not visible where they transect one another across the valleys. Apparently these valleys were filled with deposits sometime after they were formed by tectonic processes, leaving them flat and smooth. Sinuous rilles (trenches) later formed, probably by some flow process. Some type of fluid flow may well have been involved in their evolution. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01356" onclick="window.open(this.href); return false;" title="Voir l'image PIA01356: Ariel's transecting valleys sur le site de la NASA">Voir l'image PIA01356: Ariel's transecting valleys sur le site de la NASA.</a></div>
PIA01356: Ariel's transecting valleys
<h1>PIA01534: Ariel's Densely Pitted Surface</h1><div class="PIA01534" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This mosaic of the four highest-resolution images of Ariel represents the most detailed Voyager 2 picture of this satellite of Uranus. The images were taken through the clear filter of Voyager's narrow-angle camera on Jan. 24, 1986, at a distance of about 130,000 kilometers (80,000 miles). Ariel is about 1,200 km (750 mi) in diameter; the resolution here is 2.4 km (1.5 mi). Much of Ariel's surface is densely pitted with craters 5 to 10 km (3 to 6 mi) across. These craters are close to the threshold of detection in this picture. Numerous valleys and fault scarps crisscross the highly pitted terrain. Voyager scientists believe the valleys have formed over down-dropped fault blocks (graben); apparently, extensive faulting has occurred as a result of expansion and stretching of Ariel's crust. The largest fault valleys, near the terminator at right, as well as a smooth region near the center of this image, have been partly filled with deposits that are younger and less heavily cratered than the pitted terrain. Narrow, somewhat sinuous scarps and valleys have been formed, in turn, in these young deposits. It is not yet clear whether these sinuous features have been formed by faulting or by the flow of fluids.<p>JPL manages the Voyager project for NASA's Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01534" onclick="window.open(this.href); return false;" title="Voir l'image PIA01534: Ariel's Densely Pitted Surface sur le site de la NASA">Voir l'image PIA01534: Ariel's Densely Pitted Surface sur le site de la NASA.</a></div>
PIA01534: Ariel's Densely Pitted Surface
Nom d'Ariel - Lune d'Uranus

Le nom « Ariel » vient du génie aérien dans la pièce « La Tempête » de William Shakespeare. Ariel étant l'esprit bienfaisant de cette pièce, les formations géologiques remarquables portent les noms de bons esprits et d'esprits de la lumière dans les différentes mythologie : Rima, Yangoor,Domovoy, Agape, Mélusine, Finvara, Berylune...

Vidéo : © MIMATA - Planète Astronomie
Textes : Wikipédia|Licence de documentation libre GNU logo GNU