r@fermat.UUCP (Richard Schroeppel) (01/24/91)
We were debating the evidence for a tenth planet, based on perturbations of the other nine. Henry Spencer wrote: > ...(A very careful reassessment of observations of the orbit of Neptune by some folks at JPL concluded that there are no unexplained perturbations.) ... I countered with a long quote from the 1988 Astronomical Almanac, page L1; I have capitalized one sentence for emphasis: > Fundamental ephemerides of the Sun, Moon and planets were calculated by a simultaneous numerical integration at the Jet Propulsion Laboratory in a cooperative effort with the U.S. Naval Observatory. Optical, radar, laser, and spacecraft observations were analyzed to determine starting conditions for the numerical integration. In order to obtain the best fit of the ephemerides to the observational data, some modifications to the IAU (1976) System of Astronomical Constants were necessary. These modification of the constants are listed on page K7. A SATISFACTORY EPHEMERIS FOR URANUS FOR THE 1980'S COULD BE COMPUTED ONLY BY EXCLUDING OBSERVATIONS MADE BEFORE 1900. This integration, designated DE200/LE200, is available on magnetic tape for the period 1800-2050. Additional information about the new ephemerides is included in the *Supplement to the Astronomical Almanac for 1984.* I commented on the quality of the old data: > Astronomical photography was inaugurated in 1858. It should be possible to remeasure the position of Uranus accurately from old photos. Henry responded: > The JPL work I refer to was quite recent, as I recall, enough so that it might not be reflected in a three-year-old book. I've checked some additional years of the AA: The same paragraph is present in the all the editions I checked, for the years 1985, 86, 88, 90, and 91, always on page L1, the explanation chapter. So, can someone from USNO or JPL help us out? Is the orbit of Neptune ok, but that of Uranus damaged? Is JPL concealing the existence of a tenth planet? Is general relativity wrong? Is Pluto really a black dwarf? Are the Uranians manipulating their orbit just to confuse us? Was the 1991 AA printed before the Voyager Neptune flyby? Can Henry remember his reference? Rich Schroeppel rcs@la.tis.com