Latest Inner moon Stories
New research suggests that the origin of Saturn's rings may be a case of cosmic murder.
NASA's Cassini spacecraft has detected a faint, partial ring orbiting with one small moon of Saturn, and has confirmed the presence of another partial ring orbiting with a second moon.
Scientists from the University of Maryland and the Max-Planck Institute for Solar System Research in Germany appear to have solved a long-standing mystery about the cause of anomalies in Jupiter's gossamer rings.
Imaging scientists on NASA's Cassini mission are telling a tale of how the small moons orbiting near the outer rings of Saturn came to be. The moons began as leftover shards from larger bodies that broke apart and filled out their "figures" with the debris that made the rings.
While individual satellite properties vary, the systems all share a striking similarity: the total mass of each satellite system compared to the mass of its host planet is very nearly a constant ratio, roughly 1:10,000.
To the surprise of astronomers, NASA's Hubble Space Telescope has photographed a pair of new rings around the distant planet Uranus. The largest is twice the diameter of the planet's previously known rings.
New NASA Hubble Space Telescope images of the distant planet Neptune show a dynamic atmosphere and capture the fleeting orbits of its satellites. The images have been assembled into a time-lapse movie revealing the orbital motion of the satellites.
Scientists studying data from NASA's Galileo spacecraft have found that Jupiter's moon Amalthea is a pile of icy rubble less dense than water. Scientists expected moons closer to the planet to be rocky and not icy. The finding shakes up long-held theories of how moons form around giant planets.
Planetary Ring -- A planetary ring is a ring of dust and other small particles orbiting around a planet in a flat disc-shaped region. The most spectacular and famous planetary rings are those around Saturn, but all four of the solar system's gas giant planets (Jupiter, Saturn, Uranus, Neptune) possess ring systems of their own. The origin of planetary rings is not precisely known, but they are thought to be unstable and dissipate over the course of tens or hundreds of millions of...
Planet Larissa -- Larissa is the fifth of Neptune's known moons. It was discovered by Harold Reitsema based on ground-based stellar occultation observations, and was photographed by Voyager 2 in 1989. Larissa is irregular (non-spherical) in shape and appears to be heavily cratered, with no sign of any geological modification. Little else is known about it. Since its orbit is below Neptune's synchronous orbit radius it is slowly decaying due to tidal forces and will one day break up...
Uranus' moon Portia -- Portia is a moon of Uranus, named after the 2 two heroines in plays by William Shakespeare. It was discovered in 1986 by Voyager 2. Very little is known about it. Since it is below Uranus' synchronous orbit radius, Portia's orbit is slowly decaying due to tidal forces and it will one day break up into a planetary ring or impact on Uranus' surface. ----- Discovery Discovered by Voyager 2 Discovered in 1986 Orbital characteristics Orbital radius:...
Saturn's moon Janus -- Janus is a moon of Saturn discovered by the French astronomer Audouin Dollfus in 1966. Dollfus is credited with the discovery of Janus but it's not really certain whether the object he saw was Janus or Epimetheus and his observations led to a spurious orbit (Walker discovered it independently but his telegram arrived a few hours after Dollfus'). Larson and Fountain determined in 1978 that there are in fact two moons sharing one orbit. This was confirmed in 1980...
Saturn's moon Epimetheus -- Epimetheus is a moon of Saturn that was probably first observed by Walker and Audouin Dollfus in 1966 when they discovered Janus, but the situation was confused since Janus is in a very similar orbit and so Walker officially shares the discovery of Epimetheus with Fountain and Larson who showed in 1978 that there were two satellites involved. The situation was clarified in 1980 by Voyager 1. Epimetheus and Janus are "co-orbital". Janus' orbital radius from...
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