The Statistics of Scientific Incunabula

Abstract

be shown that Jupiter was in the constellation Sagittarius at R.A. I8 hrs. 35 min., Dec. 23.05 on 6 August I664. With Schlesinger's Catalogue of Bright Stars, it is found that the star HR 7128, magnitude 5.89, had the following coordinates: R.A. i8 hrs. 35.8 min., Dec. -23? 37'. In other words HR 7128 was not far from the plane of the genuine satellites and some I2 minutes of arc to the west of the planet. Satellite IV can appear over io' from its primary. The conclusion is inescapable. Star HR 7I28 was in the right place to be reasonably mistaken for a fifth moon. Therefore, the star best known nowadays as CPD -23?, I4844, appearing in Norton's and other atlases as Piazzi 225, is without doubt Winthrop's satellite, actually a naked-eye star for all to see -and not to be confused with planetary attendants. The color is blue, spectral class B8; but, low down as it was, the pioneer scientists could hardly be expected to have been impressed with the difference between it and objects shining by reflected yellow sunlight as seen in a refracting instrument not corrected for chromatic aberration. Had Winthrop looked, even without his telescope, on the next few nights, he would have seen his would-be moon being left behind in the background of stars while the ranking planet of the solar family worked slowly east, while Barnard's atellite, snug in the inner circle, was still awaiting discovery.