![]() ![]() This time, though, they had technology on their side: telescopes with electronic light detectors made searches far more sensitive than work done previously with photographic plates. This circumstantial evidence for a distant belt of bodies in the same region as Pluto drove observers back to their telescopes in search of undiscovered, faint objects. In the late 1980s, scientists determined that only something like the Kuiper Belt could explain why short-period comets orbit so close to the plane of the solar system. This concept, which became known as the Kuiper Belt, appeared in scientific literature for decades, but repeated searches for this myriad population of frosty worlds came up short. 1) 2) 3)īy the 1950s, some researchers, most notably Dutch-American astronomer Gerard Kuiper, had suggested that Pluto was not a lone oddity but the brightest of a vast collection of objects orbiting beyond Neptune. Distant Pluto was an icy stranger in a strange orbit. The other planets fit neatly into the known architecture of the solar system – four small, rocky bodies in the inner orbits and four gas giants in the outer orbits, with an asteroid belt in between. S2CID 1058405.New Horizons Mission Spacecraft Launch Sensor Complement Mission Status Referencesįor decades after American astronomer Clyde Tombaugh discovered Pluto in 1930, this small world was considered an oddity. "Cassini Imaging Science: Initial Results on Saturn's Rings and Small Satellites". Grazier, Kim Helfenstein, Paul Ingersoll, A.P. Dawson, Douglas Delgenio, Anthony Denk, T. "Of horseshoes and heliotropes: Dynamics of dust in the Encke Gap". ^ "Here's Why Saturn's Inner Moons Are Shaped Like Ravioli and Potatoes"."Stunning close-up of Saturn's moon, Pan, reveals a space empanada". "Pan, Moon of Saturn, Looks Like a Cosmic Ravioli (or Maybe a Walnut)". ^ "PIA08320: Cruising with Pan", Planetary Photojournal.^ "Planet and Satellite Names and Discoverers".^ IAUC 5347: Satellites of Saturn and Neptune 1991 September 16 (naming the moon)."Visual detection of 1981 S 13, Saturn's eighteenth satellite, and its role in the Encke gap". Bulletin of the American Astronomical Society. "Visual Detection of 1981 S 13, the Encke Gap Moonlet". "Satellite "wakes" and the orbit of the Encke Gap moonlet". Wavy Edges Suggest Moonlet in Encke's Gap, Astrophysical Journal, Vol. ^ "Saturn's Tiny Moon Pan Looks Like a Ravioli".Archived from the original on 7 September 2015. "Sizes, shapes, and derived properties of the saturnian satellites after the Cassini nominal mission" (PDF). "Revised orbits of Saturn's small inner satellites". (Subscription or participating institution membership required.) The Encke Gap, within which Pan orbits, is about 325 km wide. ![]() 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. Pan is the innermost named moon of Saturn. ![]()
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