Some of these sightings were by well-known observers, who even today have a reputation for reliability. Thus G.D.Cassini, director of the Paris Observatory and discoverer of Cassini's division in Saturn's rings, wrote in his journal for August 28, 1686:
Widespread interest was aroused when Lambert announced these reults to the Berlin Academy of Sciences. The king of Prussia, Frederick the Great, proposed that the satellite be named after his friend, the French astronomer-mathematician, Jean d'Alembert. The latter prudently declined the honor, explaining that his place on earth was so insignificant he had no ambition for one in the skies.
Yet nothing can be more certain than that no such sizable satellite exists. It has never been seen since 1768. Veteran observers of Venus such as Schroeter, William Herschel, and Maedler could not find it. More recently, E.E. Barnard, whose interest in satellites was marked, made many observations of Venus with telescopes up to the Yerkes 40-inch in size without finding any companion. Currently, scores of amateurs every year scrutinize Venus with telescopes more powerful than those with which the supposed satellite used to be seen, without coming upon this object.
The Lost Satellite of Venus
How much confirmation do you need to place an observational discovery beyond any reasonable doubt? This is the important and disturbing question raised by the story of a satellite of Venus, which at one time was confidently accepted as a member of the solar system. No fewer than 33 observations of it by 15 different astronomers were recorded during the 17th and 18th centuries, beginning with F. Fontana at Naples on November 11, 1645. In the year 1761 alone, 18 observations of the object were made."At 4.14 a.m. while examining Venus with a telescope of 34 feet focal length, I saw at 3/5 of its diameter to the east an ill-defined light, which seemed to imitate the phase of Venus, but its western edge was more flattened. Its diameter was nearly 1/4 that of Venus. I observed it with attention for a quarter of an hour, when, on quitting the telexcope for five minutes, I could not find it again, the dawn being too bright."
In 1773, the German astronomer Johann Lambert calculated the orbit of the satellite of Venus. He found that it revolved about its primary in 11 days five hours, at a mean distance of 661/2 radii of the planet, in an orbit whose eccentricity was 0.195.
[Source: Sky and Telescope, August 1954]
