![]() Its inclination, which would cause it to move up and down, is not distinguishable from zero with present data. The eccentricity of Pan's orbit causes its distance from Saturn to vary by ~4 km. This is a reference to Pan's role as a shepherd moon. The moon was named on 16 September 1991, after the mythological Pan, who was (among other things) the god of shepherds. In all, it appears in eleven Voyager 2 images. Every qualifying Voyager 2 image with resolution better than ~50 km/pixel shows Pan clearly. The search was undertaken by considering all Voyager 2 images and using a computer calculation to predict whether the moon would be visible under sufficiently favorable conditions in each one. The moon was later found within 1° of the predicted position. ![]() The actual semi-major axis differs by 19 km and the actual mass is 8.6 ×10 −12 of Saturn's. They arrived at a very precise prediction of 133,603 ± 10 km for the semi-major axis and a mass of 5–10 ×10 −12 Saturn masses, and inferred that there was only a single moon within the Encke gap. inferred its orbit and mass by modeling its gravitational wake. Scargle in 1985, based on wavy edges of the gap which indicated a gravitational disturbance. The existence of a moon in the Encke Gap was first predicted by Jeffrey N. Showalter in 1990 from analysis of old Voyager 2 probe photos and received the provisional designation S/1981 S 13 because the discovery images dated back to 1981. It is sometimes described as having the appearance of a ravioli. Pan is a ring shepherd and is responsible for keeping the Encke Gap free of ring particles. It is a small, walnut-shaped moon approximately 35 kilometres across and 23 km wide that orbits within the Encke Gap in Saturn's A Ring. "These are questions to be answered by future missions.Pan is the innermost named moon of Saturn. "Do any of the moons of the ice giant planets Uranus and Neptune interact with their thinner rings to form features similar to those on Saturn's ring moons?" Buratti asked. The lunar origin stories might be replicated throughout the solar system, scientists say. The further-out moons-Atlas, Prometheus and Pandora-feature icy blue that stems from material from larger moon Enceladus, which some believe has the potential for alien life. Detailed views of these tiny ring moons may tell us more about the behavior of the ring particles themselves," says Cassini Project Scientist Linda Spilker, also at JPL.Ĭassini saw a reddish material on the moons closer to Saturn, Daphnis and Pan, that they believe to be a mixture of iron and organics. "Perhaps this process is going on throughout the rings, and the largest ring particles are also accreting ring material around them. The process could be replicated throughout Saturn's rings, scientists say. "A denser body would be more ball-shaped because gravity would pull the material in." Instead of the common sphere, NASA describes the moons as "blobby and ravioli-like, with material stuck around their equators." "We found these moons are scooping up particles of ice and dust from the rings to form the little skirts around their equators," Buratti says. Their porousness contributes to their shape as well as their makeup. Daphnis' orbit creates a space known as the Keeler Gap, a 26 mile (42 km) gap in one of Saturn's largest and brightest rings. Some of these moons, like Daphnis, act like a snowplow after a storm, clearing a path through the rings. Large remnants of Saturn's ring material long ago broke off and eventually formed these moons. It seems that these moons are so affected by outside sources because they are highly porous, and the reason they're so porous, scientists believe, is because they formed in stages. These include "contamination by a red material formed in Saturn’s main ring system, and by accretion of bright icy particles or water vapor from volcanic plumes originating on the planet’s moon Enceladus." "The optical properties of the moons’ surfaces are determined by two competing processes," according to the study's abstract. The route allowed for an unprecedented look at these inner moons, too, using Cassini's Visible and Infrared Mapping Spectrometer (VIMS). ![]() And when the spacecraft's 19-year mission ended in 2017, NASA destroyed the beloved craft through the "Grand Finale," in which Cassini plummeted into Saturn's atmosphere via a carefully chosen route that would not disrupt any of the planet's moons. The Cassini spacecraft discovered several of those moons. An annotated map showing the location of the small moons in relation to Saturn.
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