Ron B. wrote: >Sterling W. wrote: >>"The near-Earth asteroid 3753 Cruithne is in an unusual orbit about >>that of the Earth, one which is known in the lingo of celestial >>mechanics as being co-orbital with the Earth (meaning it SHARES [my >>emphasis] the Earth's orbit with it) and, more particularly, as being of >>the "horseshoe" type.
>'Share' is a bad choice of word, since Cruithne does not share an orbit with Earth. Rod Serling List, Earth does share two-body acrobatics transfering momentum back and forth across the Solar axel with Cruithne in a basically three-body system causing this "RESONANCE" and causing an orbital SHARING of MOMENTUM, but not of PATH. At only 5 km estimated diameter of Cruithne, it is relegated to a species of space rubble, that could have an infinite number of other orbital paths that looked very different to its and Earth's current orbit and still share mome ntum equally or even more, performing amorous mechanical contortions. What we don't share is an orbital trajectory until someone wants to make an interesting story from informationless averages (over many orbits, average year = 1, average distance = 1 AU). So, the Cruithine folk are probably scratching their kneecaps now saying "those third two huge piles of rocks are gonna direct our orbit again and we'll be headed for another cool age in two or three centuries - maybe we ought to nuke 'em and be decoupled once and for all." Note that from the asteroid's point of view Earth is an integral determining factor of its orbit which cannot be determined by the Sun alone, and in that sense is co-orbital, manifesting repetitiously over orbits the same shared gravitational interactions. Cruithne currently has a perihelion of less than 0.5 AU and an aphelion of over 1.5 AU and, :-) is covered in pictographs. Saludos, Doug ______________________________________________ Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list
