The Zodiacal Light

Abstract

MR. O. T. SHERMAN gives an interesting communication on the zodiacal light in NATURE of October 18 (p. 594), and asks for reference to any observations. He alludes to Cassini, The following extract from a letter by Cassini may not have come under his notice: “It is a remarkable circumstance that since the end of the year 1688, when this light began to grow fainter, spots should have no longer appeared on the sun, while in the preceding years they were very frequent, which seems to support, in a manner, the conjecture that the light may arise from the same emanations as the spots and faculæ of the sun.” This does not quite tally with Mr. Sherman's notion that the maxima of the zodiacal light coincide with the minima of sun-spots. May it not rather be that, supposing sun-spots to be largely occasioned by increased influx of meteoric matter falling into the sun, which matter gets sublimed and repulsed to augment the materials forming the zodiacal light, therefore the maxima of the latter may then lag behind the maxima of the sun-spots.