something else. The albedo of cloud is 72 per cent of absolute whiteness. What looks like cloud, then, is such, on that distant
I.
Jupiter and its wisps.—A Drawing by Dr. Lowell, April 11, 1907.
disk. But Jupiter surpasses cloud in lustre, since his albedo exceeds 72 per cent. Yet a large part of his surface is strikingly darker than that. The inference from this is that he shines by intrinsic light, in part at least. The fact may not be stated dogmatically, as there is no astronomic determination so uncertain as this one of determining albedoes, and therefore Herr Müller's
II.
Jupiter and its wisps—A. Drawing by Dr Lowell, April 11, 1907
results must be accepted with every reserve, but they suggest that Jupiter is still a semi-sun, to be recognized as such by light as well as heat, though his self-luminosity, if it exist at all, can hardly exceed a dull red glow.
A modern detection on Jupiter's disk has been that of wisps or lacings across the bright equatorial belt, a detail of importance due to Mr. Scriven Bolton.
