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Fichier:Saturn from Hubble.jpg

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Description

Description
English: Looming like a giant flying saucer in our outer solar system, Saturn puts on a show as the planet and its magnificent ring system nod majestically over the course of its 29-year journey around the Sun. A series of Hubble Space Telescope images, captured from 1996 to 2000, show Saturn's rings open up from just past edge-on to nearly fully open as it moves from autumn towards winter in its Northern Hemisphere (for the composite view of all images seePIA03156.

Saturn's equator is tilted relative to its orbit by 27 degrees, very similar to the 23-degree tilt of the Earth. As Saturn moves along its orbit, first one hemisphere, then the other is tilted towards the Sun. This cyclical change causes seasons on Saturn, just as the changing orientation of Earth's tilt causes seasons on our planet. The first image in this sequence, on the lower left, was taken soon after the autumnal equinox in Saturn's Northern Hemisphere (which is the same as the spring equinox in its Southern Hemisphere). By the final image in the sequence, on the upper right, the tilt is nearing its extreme, or winter solstice in the Northern Hemisphere (summer solstice in the Southern Hemisphere).

Astronomers are studying this set of images to investigate the detailed variations in the color and brightness of the rings. They hope to learn more about the rings' composition, how they were formed, and how long they might last. Saturn's rings are incredibly thin, with a thickness of only about 30 feet (10 meters). The rings are made of dusty water ice, in the form of boulder-sized and smaller chunks that gently collide with each other as they orbit around Saturn. Saturn's gravitational field constantly disrupts these ice chunks, keeping them spread out and preventing them from combining to form a moon. The rings, as shown here, have a slight pale reddish color due to the presence of organic material mixed with the water ice.

Saturn is about 75,000 miles (120,000 km) across, and is flattened at the poles because of its very rapid rotation. A day is only 10 hours long on Saturn. Strong winds account for the horizontal bands in the atmosphere of this giant gas planet. The delicate color variations in the clouds are due to smog in the upper atmosphere, produced when ultraviolet radiation from the Sun shines on methane gas. Deeper in the atmosphere, the visible clouds and gases merge gradually into hotter and denser gases, with no solid surface for visiting spacecraft to land on.

The Cassini/Huygens spacecraft, launched from Earth in 1997, is well on its way to the Saturn system. It will arrive in 2004 to land a probe on Titan, Saturn's largest moon, and to orbit the planet for four years for a detailed study of the entire Saturn system.

These images of Saturn were taken with the Wide Field Planetary Camera 2 onboard Hubble.
Date
Source JPL Photojournal
Auteur NASA and The Hubble Heritage Team (STScI/AURA)Acknowledgment: R.G. French (Wellesley College), J. Cuzzi (NASA/Ames), L. Dones (SwRI), and J. Lissauer (NASA/Ames)


Cette image ou vidéo a été cataloguée par le
Jet Propulsion Lab
de la
National Aeronautics and Space Administration
(NASA) des États-Unis sous Photo ID : PIA03158.

Ce bandeau n’indique rien sur le statut de l’œuvre au regard du droit d'auteur. Un bandeau de droit d’auteur est requis. Voir Commons:À propos des licences pour plus d’informations.
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Cette image ou vidéo a été cataloguée par le
Space Telescope Science Institute
de la
National Aeronautics and Space Administration
(NASA) des États-Unis sous Photo ID : STSCI-PRC01-15A ; et Alternate ID : PRC01-15A.

Ce bandeau n’indique rien sur le statut de l’œuvre au regard du droit d'auteur. Un bandeau de droit d’auteur est requis. Voir Commons:À propos des licences pour plus d’informations.

Conditions d’utilisation

Public domain
This file is in the public domain because it was created by NASA and ESA. NASA Hubble material (and ESA Hubble material prior to 2009) is copyright-free and may be freely used as in the public domain without fee, on the condition that only NASA, STScI, and/or ESA is credited as the source of the material. This license does not apply if ESA material created after 2008 or source material from other organizations is in use.

The material was created for NASA by Space Telescope Science Institute under Contract NAS5-26555, or for ESA by the Hubble European Space Agency Information Centre. Copyright statement at hubblesite.org or 2008 copyright statement at spacetelescope.org.

For material created by the European Space Agency on the spacetelescope.org site since 2009, use the {{ESA-Hubble}} tag.

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actuel9 novembre 2004 à 07:33Vignette pour la version du 9 novembre 2004 à 07:333 000 × 1 500 (117 kio)Gentgeen{{PD-USGov-NASA}}

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