SUMMARY / RELATED TOPICS

Centaur (small Solar System body)

Centaurs are small Solar System bodies with either a perihelion or a semi-major axis between those of the outer planets. They have unstable orbits because they cross or have crossed the orbits of one or more of the giant planets. Centaurs behave with characteristics of both asteroids and comets, they are named after the mythological centaurs that were a mixture of human. Observational bias toward large objects makes determination of the total Centaur population difficult. Estimates for the number of Centaurs in the Solar System more than 1 km in diameter range from as low as 44,000 to more than 10,000,000The first Centaur to be discovered, under the definition of the Jet Propulsion Laboratory and the one used here, was 944 Hidalgo in 1920. However, they were not recognized as a distinct population until the discovery of 2060 Chiron in 1977; the largest confirmed Centaur is 10199 Chariklo, which at 260 kilometers in diameter is as big as a mid-sized main-belt asteroid, is known to have a system of rings.

It was discovered in 1997. However, the lost Centaur 1995 SN55 may be somewhat larger; the transneptunian object 2018 VG18, a Centaur under the broader definition, may be quite a bit larger. No Centaur has been photographed up close, although there is evidence that Saturn's moon Phoebe, imaged by the Cassini probe in 2004, may be a captured Centaur that originated in the Kuiper belt. In addition, the Hubble Space Telescope has gleaned some information about the surface features of 8405 Asbolus. 1 Ceres may have originated in the region of the outer planets, if so might be considered an ex-Centaur, but the Centaurs seen today all originated elsewhere. Of the objects known to occupy Centaur-like orbits 30 have been found to display comet-like dust comas, with three, 2060 Chiron, 60558 Echeclus, 29P/Schwassmann-Wachmann 1, having detectable levels of volatile production in orbits beyond Jupiter. Chiron and Echeclus are therefore classified as both asteroids and comets, while Schwassmann-Wachmann 1 has always held a comet designation.

Other Centaurs, such as 52872 Okyrhoe, are suspected of having shown comas. Any Centaur, perturbed close enough to the Sun is expected to become a comet; the generic definition of a Centaur is a small body that orbits the Sun between Jupiter and Neptune and crosses the orbits of one or more of the giant planets. Due to the inherent long-term instability of orbits in this region Centaurs such as 2000 GM137 and 2001 XZ255, which do not cross the orbit of any planet, are in changing orbits that will be perturbed until they start to cross the orbit of one or more of the giant planets; some astronomers count only bodies with semimajor axes in the region of the outer planets to be Centaurs. However, different institutions have different criteria for classifying borderline objects, based on particular values of their orbital elements: The Minor Planet Center defines Centaurs as having a perihelion beyond the orbit of Jupiter and a semi-major axis less than that of Neptune. Though nowadays the MPC lists Centaurs and scattered disc objects together as a single group.

The Jet Propulsion Laboratory defines Centaurs as having a semi-major axis, a, between those of Jupiter and Neptune. In contrast, the Deep Ecliptic Survey defines Centaurs using a dynamical classification scheme; these classifications are based on the simulated change in behavior of the present orbit when extended over 10 million years. The DES defines Centaurs as non-resonant objects whose instantaneous perihelia are less than the osculating semi-major axis of Neptune at any time during the simulation; this definition is intended to be synonymous with planet-crossing orbits and to suggest comparatively short lifetimes in the current orbit. The collection The Solar System Beyond Neptune defines objects with a semi-major axis between those of Jupiter and Neptune and a Jupiter-relative Tisserand's parameter above 3.05 as Centaurs, classifying the objects with a Jupiter-relative Tisserand's parameter below this and, to exclude Kuiper belt objects, an arbitrary perihelion cut-off half-way to Saturn as Jupiter-family comets, classifying those objects on unstable orbits with a semi-major axis larger than Neptune's as members of the scattered disc.

Other astronomers prefer to define Centaurs as objects that are non-resonant with a perihelion inside the orbit of Neptune that can be shown to cross the Hill sphere of a gas giant within the next 10 million years, so that Centaurs can be thought of as objects scattered inwards and that interact more and scatter more than typical scattered-disc objects. The JPL Small-Body Database lists 452 Centaurs. There are an additional 116 trans-Neptunian objects with a perihelion closer than the orbit of Uranus; the Gladman & Marsden criteria would make some objects Jupiter-family comets: Both Echeclus and Okyrhoe have traditionally been classified as Centaurs. Traditionally considered an asteroid, but classified as a Centaur by JPL, Hidalgo would change category to a Jupiter-family comet. Schwassmann-Wachmann 1 has been categorized as both a Centaur and a Jupiter-family comet depending on the definition used. Other objects caught between these differences in classificati

Graphic Communications Conference

The Graphic Communications Conference is an International Brotherhood of Teamsters affiliated union which represents more than 60,000 workers in all craft and skill areas in the printing and publishing industry. Every day, GCC members help print and design numerous publications, including: The New York Times, Chicago Sun-Times, San Francisco Chronicle, New York Newsday and Cosmopolitan magazines. L. Bean. GCC Teamsters work in desktop publishing and electronic color prepress, they operate web and sheetfed, letterpress, rotogravure and other specialty presses. They handle binding and shipping of finished products, they produce inks and packaging materials made of paper, plastic and metal. They are journalists, graphic artists, sales people, support staff. According to GCC's Department of Labor records since 2006, when membership classifications were first reported, the "active" membership of the union has fallen from 60% to 45%; the other—now 55%—half of the union's membership are classified as "honorary," and are described as retirees who pay no dues and are ineligible to vote in the union.

GCC contracts cover some non-members, known as agency fee payers, which since 2006 have numbered comparatively less than a percent of the size of the union's membership, or about 100 non-members paying agency fees. The conference was created after the Graphic Communications International Union voted to join forces with Teamsters in late 2004; the merger enables the now-stronger Teamsters Union to represent more workers in printing and related industries. For example, the GCC and the Teamsters Newspaper Division represent different but complementary types of employees at many major newspapers, such as the Cleveland Plain Dealer, The Boston Globe, Boston Herald, The Columbus Dispatch and The Star-Ledger in New Jersey. George Tedeschi serves as President; the Graphic Communications Conference of the International Brotherhood of Teamsters, Local 767M is the successor union of several merged printers' locals spanning back into the late 1800s. The local unions have been affiliated with different international unions over time.

Santa Barbara News-Press controversy Graphic Communications International Union, Local 767M records. 1908-2009. 15.38 cubic feet. At the Labor Archives of Washington State, University of Washington Libraries Special Collections

1983 in Sweden

Events from the year 1983 in Sweden Monarch – Carl XVI Gustaf Prime Minister – Olof Palme 1 January – the Name Act of 1982, replacing the Name Act of 1963, comes into full and legal effect. The Tiveden National Park was established 16 September – Beyond Sorrow, Beyond Pain released 21 February – Emilie O'Konor, ice hockey player 28 February – Sara Nordenstam, Swedish-born Norwegian swimmer 9 May – Petter Stymne, swimmer 7 July – Nanna Jansson, ice hockey player 6 September – Johanna Wiberg, handball player. 9 September – Frej Larsson, musician 17 October – Åsa Persson, figure skater 15 December – Jonas Persson, swimmer. Anna Maria Nilsson, biathlete 22 February – Georg Rydeberg, film actor