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Conjunction: Moon and JupiterImage credit: Joe…

Conjunction: Moon and Jupiter

Image credit: Joe Stieber

Saturn Rings and Moons: From left, the moons…

Saturn Rings and Moons: From left, the moons are Janus, Pandora, Enceladus, Mimas and Rhea. Following the images below, Enceladus e Tethys, Titan, Rhea and Mimas. Enceladus e Tethys.

by Gordan Ugarkovic

Andromeda’s actual size if it was brig…

Andromeda’s actual size if it was brighter

via reddit

The Moon is lit by the golden colours of sunse…

The Moon is lit by the golden colours of sunset and Venus is just about to get occulted disappearing behind the dark limb of the Moon.

Image credit: Luis Argerich

This scene, captured with a 35mm camera from i…

This scene, captured with a 35mm camera from inside the Space Shuttle Endeavour, shows Jupiter rising above the airglow over Earth’s horizon. The crescent Moon is at top frame.

Credit: NASA

What’s Your favorite space object?

What’s Your favorite space object?

The mosaic shown here was composed with data…

The mosaic shown here was composed with data from Cassini’s visual and infrared mapping spectrometer taken during the Titan flyby Dec. 26, 2005.

Credit: NASA

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Night sky just after sunset on March 24, 2012 …

Night sky just after sunset on March 24, 2012 with crescent moon and backlight, Jupiter, Venus and the Pleiades.

by

Ritzelmut

In 40 million years, Mars may have a ring (a…

In 40 million years, Mars may have a ring (and one fewer moon)

Nothing lasts forever – especially Phobos, one of the two small moons orbiting Mars. The moonlet is spiraling closer and closer to the Red Planet on its way toward an inevitable collision with its host. But a new study suggests that pieces of Phobos will get a second life as a ring around the rocky planet.

A moon – or moonlet – in orbit around a planet has three possible destinies. If it is just the right distance from its host, it will stay in orbit indefinitely. If it’s beyond that point of equilibrium, it will slowly drift away. (This is the situation with the moon; as it gradually pulls away from Earth, its orbit is growing by about 1.5 inches per year.) And if a moon starts out on the too-close side, its orbit will keep shrinking until there is no distance left between it and its host planet.

The Martian ring will last for at least 1 million years – and perhaps for as long as 100 million years, according to the study.

The rest of Phobos will probably remain intact, until it hits the Martian surface. But it won’t be a direct impact; instead, the moonlet’s remains will strike at an oblique angle, skipping along the surface like a smooth stone on a calm lake.

This has probably happened before – scientists believe a group of elliptical craters on the Martian surface were caused by a small moon that skidded to its demise. (If this were to happen on Earth, our planet’s greater mass would produce a crash as big as the one that wiped out the dinosaurs, the researchers noted as an aside.)

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images: NASA/JPL,

Tushar Mittal using Celestia 2001-2010, Celestia Development Team.