Hidden companion.Earth has a second companion. In contrast to the moon, which orbits our planet, this body, an asteroid called 3753, moves about the sun. Moreover, the asteroid stays at least 40 times farther from Earth than the moon does. Nonetheless, new computer simulations reveal that the 5-kilometer-wide body is locked in a peculiar gravitational grav·i·ta·tion n. 1. Physics a. The natural phenomenon of attraction between physical objects with mass or energy. b. The act or process of moving under the influence of this attraction. 2. dance with Earth and the sun, causing the asteroid to have the same orbital period The orbital period is the time taken for a planet (or another object) to make one complete orbit. When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars. as Earth. When the rock creeps ahead of Earth, our planet nudges it into an orbit farther from the sun, where it slows down. When the rock lags behind, Earth pulls it into a closer orbit, where it speeds up. Viewed from Earth, the asteroid appears to move in a horseshoe path, the only asteroid known to do so. Although this partnership has apparently endured for thousands of years, the Years, The the seven decades of Eleanor Pargiter’s life. [Br. Lit.: Benét, 1109] See : Time rock's dancing days may be numbered. A close approach by Venus in 8,000 years may dislodge the asteroid from its orbit. Paul A. Wiegert and Kimmo A. Innanen of York University York University, at North York, Ont., Canada; nondenominational; coeducational; founded 1959 as an affiliate of the Univ. of Toronto, became independent 1965. in North York, Ontario North York forms the central part of the northern half of Toronto, Ontario, Canada. As of the 2006 Census, it has a population of 624,610. The official 2001 census count was 608,288. , and Seppo Mikkola of Tuorla Observatory in Piikkio, Finland, detail their finding in the June 12 NATURE. |
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