First image: Ida's moon stars on film.Early last month, NASA NASA: see National Aeronautics and Space Administration. NASA in full National Aeronautics and Space Administration Independent U.S. scientists reported that the Galileo spacecraft had probably made the first direct detection of a moon orbiting an asteroid (SN: 3/12/94, p. 164). Now they're sure. A complete image, relayed by the craft on March 15 and released by the space agency last week, shows that a tiny moon circles the asteroid 243 Ida. The picture reveals that the moon, informally dubbed Ida 2, measures about 1.5 kilometers wide and lies roughly 100 km from the center of the asteroid. Data from Galileo's near-infrared mapping spectrometer indicate that the moon, like Ida, has a high proportion of silicates. If images of Ida to be radioed between now and June also show the moon, researchers could determine the satellite's 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. . This, in turn, would reveal the density of Ida and its similarity to that of certain classes of meteorites Meteorites See also astronomy. aerolithology the science of aerolites, whether meteoric stones or meteorites. Also called aerolitics. astrolithology the study of meteorites. Also called meteoritics. . The moon seems to resemble the asteroid it orbits, but researchers debate whether the tiny rock is more akin to a daughter or a sister of Ida. Based in part on the aster0id's assumed lineage, some scientists favor the sister scenario, notes Clark R. Chapman of the Planetary Science planetary science or planetology, study of planets and planetary systems as a whole. Planetary science applies the theories and methods of traditional disciplines such as astronomy, geology, physics, chemistry, and mathematics to the study of Institute in Tucson. Ida belongs to the Koronis family of asteroids This is a list of numbered minor planets, nearly all of them asteroids, in sequential order. As of late September 2007 there are 164,612 numbered minor planets, and many more not yet numbered. Most asteroids are ordinary and not particularly noteworthy. , apparently created when a collision shattered a larger parent body into 100 or more pieces. Chapman speculates that Ida 2 may represent a small fragment of the Koronis family - a tiny sister of Ida - that because of its proximity and similar velocity becomes gravitationally 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. bound to the asteroid. Alternatively, the moon may represent a true daughter of Ida - a chip off the old asteroid knocked free long after the creation of the Koronis family. In this scenario, a projectile projectile something thrown forward. projectile syringe see blow dart. projectile vomiting forceful vomiting, usually without preceding retching, in which the vomitus is thrown well forward. rammed into Ida, gouging Gouging can be:
Scientists say it's unlikely that Ida 2 is a relic of the creation of the solar system. A fragment that old would probably have been shattered long ago by collisions in the asteroid belt. Galileo found a moon after imaging only two asteroids from space. However, it remains unclear whether most asteroids, or just those that belong to families, have moons. Some scientists recording the decline in light when an asteroid passes in front of a star have reported a brief "blinkout" before or after the actual eclipse. They have attributed these blinkouts to asteroid moons. The discovery of Ida 2 may lend more credibility to these reports, the Galileo team says. |
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