Page:Across the Zodiac (Volume 1).djvu/65

 in their turn were more notably distinct; their variety of colour as well as the contrast of light and shade much more definite, and their irregularities more unmistakable. A satellite was approaching the disc, and this afforded me an opportunity of realising with especial clearness the difference between observation through seventy or a hundred miles of terrestrial atmosphere outside the object glass and observation in space. The two discs were perfectly rounded and separately discernible until they touched. Moreover, I was able to distinguish upon one of the darker bands the disc of the satellite itself, while upon a lighter band its round black shadow was at the same time perfectly defined. This wonderfully clear presentation of one of the most interesting of astronomical phenomena so absorbed my attention that I watched the satellite and shadow during their whole course, though the former, passing after a time on to a light band, became comparatively indistinct. The moment, however, that the outer edge passed off the disc of Jupiter, its outline became perfectly visible against the black background of sky. What was still more novel was the occultation for some little time of a star, apparently of the tenth magnitude, not by the planet but by the satellite, almost immediately after it passed off the disc of the former. Whether the star actually disappeared at once, as if instantaneously extinguished, or whether, as I thought at the moment, it remained for some tenth of a second partially visible, as if refracted by an atmosphere belonging to the satellite, I will not venture to say. The bands and rings of Saturn, the division between the two latter, and the seven satellites, were also perfectly visible, with a dis-