![]() ![]() Much of the divergence hinged on Lowell’s claims that while his telescopes were of smaller aperture, seeing conditions at the high and dry elevation of Mars Hill were unequaled. They were most glaring with respect to the putative martian canals and similar features as depicted by Percival Lowell and others. These strident comments, well documented in William Sheehan’s memorable biography of Barnard, The Immortal Fire Within, point to the rivalry and disagreements between the two observatories. In appearance, from the drawings, these markings very much resemble those seen at the same observatory upon Mars, Venus and Mercury.” Douglass’ drawings and statements, he finds these satellites covered by a series of fine dark lines, the maximum width being estimated at less than 0.1″ or 200 miles. Douglass’ paper on the third and fourth satellites of Jupiter.” After Barnard mentioned that he used the much larger 36-inch Lick refractor to make his observations, he wryly added, “According to Mr. In sharp contrast to Douglass and Pickering, Barnard’s drawings of Ganymede and Callisto show far more diffuse features: “Though conspicuous enough, they were so vague in form that at no two times was it possible to say definitely that the same marking was under observation.” He goes on to say, “I have been very much interested in Mr. In his subsequent 1897 paper, Douglass appears more certain of the key markings he described: “On February 20th … an interval of extremely good seeing revealed the Great Northern Belt in longitude 260° to 20°, with perfect distinctiveness and definition.” Other astronomers later showed that Jupiter’s main moons are tidally locked and rotate synchronously with their planet like our Moon. The north polar cap seen by some observers is immediately north of this conspicuous northern belt and is probably caused by contrast.” It shows that the rotation of detail agrees with revolution about Jupiter within 15 minutes. ![]() Its position is easily determined, and between 18 gives a means for measuring very exactly the rotation period. The northern belt becomes visible 2.2 after superior conjunction. The detail is conspicuous, and consists of northern and southern belts parallel to the equator, and other markings. Ganymede is summarized as: “The third satellite was observed with much greater ease and gave more satisfactory results. The Lowell observations show predominantly banded and crossed streaks on all four satellites, and also provide detailed descriptions of each. After moving to the University of Arizona in 1906, Douglass became head of Steward Observatory and founded the new science of dendrochronology, which dates historic events using the annual growth rings of trees. He was later dismissed by Lowell for doubting their reality. That undoubtedly colored his impressions that they appeared elliptical through the telescope, as well as accounts for his obsession with measuring their “ellipticity.” Other observers subsequently showed that the presumptive ellipticity of the moons reported by Pickering was illusory, likely due to contrast or astigmatic effects.ĭouglass, a talented astronomer and botanist, was at that time strongly influenced by his boss, Percival Lowell, regarding his views of Mars and its putative network of canals. Pickering was a rather eccentric individual among other extraordinary theories, he believed that Jupiter’s moons were not solid bodies but low-density aggregates of dust and meteoric debris. ![]() ![]() He published the results in the prestigious journal Astronomische Nachrichten in 1897, including a map of the features he recorded. Douglass subsequently undertook a more detailed study of Ganymede with the newly commissioned 24-inch Clark refractor at Flagstaff. ![]()
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