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Pourquoi la durée de visibilité de la Lune varie-t-elle autant. An Illustrated Guide to Space Maps. Nebra Sky Disc, Germany, 1600 BC.

An Illustrated Guide to Space Maps

(Photo: Rainer Zenz/WikiCommons CC BY-SA 3.0) With its patinated bronze background and shiny gold sun, moon and stars, the 3600-year-old Nebra Sky Disc is worth gazing at for its beauty alone. But the ancient object is cool for a lot of other reasons: It’s the earliest depiction of outer space we’ve ever found, and it’s also thought to be the oldest known portable astronomical instrument. For as long as humans have stared at the sky, we have sought to understand our place in the cosmos. This lovely orb is one of a long line of attempts of humans to map the unmappable—space.

The story behind the disc’s discovery is almost as crazy as the disc itself: it was dug up by metal-detector- wielding treasure hunters in 1999, along with “two swords, two axes, a chisel, and fragments of armlets.” Is it art or science? From the Harmonia Macrocosmica, Holland, 1660. From the Harmonia Macrocosmica, Holland, 1660. "Idea dell'Universo. " "Systema Solare et Planetarium. " Colonization of the Moon.

1986 artist concept The colonization of the Moon is the proposed establishment of permanent human communities or robot industries[1] on the Moon. Recent indication that water might be present in noteworthy quantities at the lunar poles has renewed interest in the Moon. Polar colonies could also avoid the problem of long lunar nights – about 354 hours,[2] a little more than two weeks – and take advantage of the sun continuously, at least during the local summer (there is no data for the winter yet).[3] Permanent human habitation on a planetary body other than the Earth is one of science fiction's most prevalent themes.

Moon Phases Calendar / Moon Schedule. Planets - How would having multiple moons affect tides? - Worldbuilding Stack Exchange. You can model the effect of two moons by summing two sine waves.

planets - How would having multiple moons affect tides? - Worldbuilding Stack Exchange

To do this plot each moon as a function of Time and manipulate the gravity of the moon by changing the amplitude and the orbital period by multiplying the time variable. A final plot showing the summation of the others gives the resulting forces on the tides. Long Version In reality calculating tides is VERY complicated, it depends on many factors involving river emptying into the sea, the terrain around the shore, currents, weather etc... However, we can come up with a rough approximation which will at least help us get a feel for how the tides would work. The first thing to establish is whether the moons would have to have the same orbital period (do they both take either same amount of time to orbit the planet?) Next you need to determine whether both moon are on the orbital plane, I would suggest they are. So you've got two moons of different masses orbiting at different periods. You can plot this like so:

How 2 moons would affect weather and tides ? La ceinture d'astéroïdes. On entend souvent parler de météorites ou encore d'astéroïdes qui se seraient ou qui vont s'écraser sur Terre.

La ceinture d'astéroïdes

Mais d'où viennent ces objets célestes ? Et combien on dénombre-t-on ? Il faut savoir que ces corps sont pour la plupart rassemblés sous forme de cercle gravitant autour du Soleil, et que l'on appelle ceinture principale, où ceinture d'astéroïdes. Dans le système solaire, il y a bien plus d'astéroïdes que de planètes. Les chercheurs en découvrent plusieurs milliers chaque année ! Située entre Mars et Jupiter, la ceinture d'astéroïdes est donc composée de milliards d'astéroïdes de toutes tailles, le plus gros faisant environ 1000 km de diamètre, et les plus petits ont la taille d'un galet.

Ces corps rocheux sont de formes très variées, les plus gros étant plutôt sphériques, tandis que les plus petits ont des formes irrégulières. Découverte des premiers astéroïdes On a découvert les tous premiers astéroïdes vers le début du 19ème siècle. Origines de la ceinture principale. Lagrange points animation. Astronomie ressources. How we'll live on Mars. How Big Is Space – Interactive version. The Orbital Dance of Epimetheus and Janus. Posted by Emily Lakdawalla Topics: Cassini, pretty pictures, amateur image processing, Saturn's small moons, Voyager 1 and 2, Saturn's moons, global views, many worlds, animation NASA / JPL / SSI / Emily Lakdawalla Epimetheus on March 30, 2005 This was Cassini's first high-resolution view of Epimetheus, captured from a range of about 75,000 kilometers and a phase angle of about 115 degrees.

The Orbital Dance of Epimetheus and Janus

The image has been magnified by a factor of two from its original size. Janus on August 25, 1981 Voyager 2 captured this view of Janus on August 25, 1981. Saturn is surrounded by a crowded family of rings and moons, and two of those moons -- Epimetheus and Janus -- orbit Saturn so close together that it seems as though their different orbital speeds should make them crash into each other. Here is how the dance works. The mutual tugging caused them to exchange angular momentum. Credit: Emily Lakdawalla Explanation of the orbital ’swap’ of Janus and Epimetheus Credit: NASA / JPL / David Seal.

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