Glossary term: Lunes

Description: Les lunes sont des corps célestes en orbite autour de planètes, de planètes naines ou d'objets plus petits tels que les astéroïdes. La Terre possède une lune, appelée la Lune. La plupart des autres planètes du système solaire ont des lunes, à l'exception de Mercure et de Vénus. La planète naine Pluton possède plusieurs lunes, tout comme un petit nombre d'autres planètes naines et d'astéroïdes. Les lunes sont des satellites naturels ; les satellites artificiels, tels que ceux utilisés pour les communications ou à des fins scientifiques, ne sont pas des lunes.

De nombreuses lunes se sont formées en orbite autour de la planète, de la planète naine ou d'un autre corps qu'elles orbitent. On pense que la Lune s'est formée en orbite autour de la Terre à partir de matériaux éjectés lors d'une collision majeure entre la Terre et un planétoïde à un stade précoce de la formation du système solaire. De nombreuses autres lunes (pour la plupart plus petites) sont des astéroïdes qui ont été capturés par la gravité de l'objet autour duquel ils gravitent.

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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher
The translation of this term and its definition is still awaiting approval

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Related Media

The planet Jupiter with the two of the four Galilean moons (visible as bright dots) orbiting it.

Jupiter's Rotation, by Vishal Sharma, India

Caption: Third place in the 2021 IAU OAE Astrophotography Contest, category Galilean moons: Jupiter’s Rotation, by Vishal Sharma, India. This time-lapse beautifully shows the rotation of Jupiter and the passage of two Galilean moons on the right side of the frame. Jupiter completes one rotation in just under 10 hours and we see as the Great Red Spot makes its way from left to right. The two moons travel a noticeable fraction of their orbit in this short time. This image was taken in 2020 in the North of India.
Credit: Vishal Sharma/IAU OAE

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons

The planet Jupiter, seen here as a bright disk, is orbited by the four Galilean moons, seen here as bright dots

Jupiter Moons Movie2, by Nicolas Hurez, Paul-Antoine Matrangolo, and Carl Pennypacker, United States of America

Caption: Second place in the 2021 IAU OAE Astrophotography Contest, category Galilean moons. This sequence shows the orbit of the four Galilean moons around the planet Jupiter. Almost two entire orbits of the innermost moon, Io, can be seen, with the other moons (Europa and Ganymede, but in particular Callisto) being further away, orbiting noticeably slower. The images were obtained in 2018 with the Las Cumbres Global Observatory at different locations on Earth, allowing a continuous sequence of images over approximately half a week without gaps during the day. With clear skies and over the course of several nights, the motion of the Galilean moons can also be observed with binoculars (ideally steady your elbows on a surface).
Credit: Nicolas Hurez, Paul-Antoine Matrangolo and Carl Pennypacker/IAU OAE

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons

Jupiter with coloured horizontal bands of clouds. The shadow of the moon Io is seen as a dark circle in the top left

Jupiter, Io and its shadow, by Ralf Burkart, Germany

Caption: First place in the 2021 IAU OAE Astrophotography Contest, category Galilean moons. This time-lapse of Jupiter taken in 2017 from Germany beautifully illustrates the transit of one of the Galilean moons, Io, in front of Jupiter. As this is simply a moon casting a shadow on a planet it is equivalent to a lunar eclipse on Earth observed from further away. While the shadow of the moon is clearly visible from the beginning, it might be difficult to spot the moon itself against the background of the beautiful atmospheric bands of Jupiter the first time the video is seen. Watching it repeatedly allows appreciating the rapid motion and rotation in this fantastic observation.
Credit: Ralf Burkart/IAU OAE

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons

La Lune presque pleine avec des cratères, des hauts plateaux clairs et des plaines sombres

Pleine lune

Caption: L'image montre la lune presque pleine, observée avec un petit télescope et un appareil photo APRN.
Credit: Luc Viatour credit link

License: CC-BY-SA-3.0 Creative Commons Attribution - Partage dans les Mêmes Conditions 3.0 non transposé icons

Io est peu ou prou sphérique. On y trouve des composés sulfuriques jaunâtres et de petits volcans plus sombres.

Io

Caption: Le 3 juillet 1999, la sonde spatiale Galileo de la NASA a acquis les images à la plus haute résolution du satellite de Jupiter Io. Io est l'une des quatre lunes joviennes découvertes par Galilée en 1610. Les couleurs de Io témoignent de son importante activité volcanique, car elles proviennent de composés sulfuriques. Les forces de marée de Jupiter et des satellites voisins sont à l'origine du volcanisme de Io.
Credit: NASA/JPL/Université d'Arizona credit link