Sky & Telescope September 1986 [antikvár]

The Celestial SolitaireGordon Moyer, Rittenhouse Astronomical SocietyA THOUSAND miles off the east coast of Madagascar, a barren range of hills rises from the Indian Ocean. It is the island of Rodrigues, which played a small but curious role in the history of two sciences: astronomy and ornithology. The story of how this island's unique do-do-like solitaire was, or rather was not, placed in the heavens dates back to 1761 and a French expedition to observe the passage of Venus across the Sun.An account of this expedition is contained in Voyage á Rodrigue, a manuscript by the expedition's leader, Abbé Al-exandre-Gui Pingré. An astronomer and Augustinian monk, Pingré left Paris for Rodrigues in November, 1760, under the auspices of the Académie Royale des Sciences. His expedition was only one of many dispatched to faraway places, for astronomers hoped that timings of the transit of Venus would yield a more accurate size for the Earth's orbit.The ll-by-5-mile, sparsely inhabited island of Rodrigues was selected as an observing station because of its favorable southerly and easterly location. Less favorable, however, was the island's weath-er. After having endured half a year at sea, Pingré arrived on May 28, 1761, just nine days before the transit. Alas, wind and clouds spoiled his observations. The trip, however, was not without scientific benefit, for Pingré spent some time viewing the island's plant and animal life.One species the abbé sought, though in vain, was the Rodrigues solitaire. Its only known portrait from life is found in Voyage et Avantures de Francois Leguat, published in 1708. Leguat headed a shortlived colony on Rodrigues in the I690's. In his own account, Pingré often compared his observations with those given by Leguat. The drawing of a solitaire is accompanied by a description of the bird's curious habits and appearance. Leguat reports that it stood taller than a turkey, weighed up to 45 pounds, and had short, knobby wings.The mysterious solitaire might have remained of interest only to naturalists had it not been for Abbé Pingré's close friend, astronomer Pierre-Charles Le Monnier. Fifteen years after the voyage, Le Monnier proposed to the French Academy that a constellation commemorating the Rodrigues expedition be added to the heavens. The figure, made up mostly of 22 faint stars above the tail of Hydra, was intended to represent the flightless solitaire.However, an engraving of Le Monnier's "constellation du Solitaire" shows a sleek songbird perched on a twig and not the long-legged, stout-bodied solitaire of Rodrigues. In fact, the bird in the illustration is a female blue rock thrush, commonly called at that time the solitaire of the Philippines. The error was first pointed out in 1846 by the Russian naturalist Josif Khristianovich Hamel. Apparently, as the British biologist Hugh Strickland suggested a few years later, Le Monnier was "a better astronomer than ornithologist."Did Le Monnier really confuse the Phil-Ahove; The extinct Rodrigues solitaire as illustrated in Francois Leguat's book. Left; The constellation of the Solitaire, depicted as a blue rock thrush, as originally introduced by Pierre-Charles Le Monnier in 1776. Ecliptic coordinates are for 1750 in tliis engraving by Yves Marie Le Gouaz that appeared in the Mémoires of the Académie Royale des Sciences, 1776.214 Sky & Telescope, September, 1986