Our Astronomical Column

Abstract

Comets.—Prof. G. van Biesbroeck records, in Pop. Astr. for March, a remarkable increase of light in comet Schwassmann-Wachmann (1), which passed perihelion nearly six years ago, and is now more than seven units from the sun. In the middle of January, its magnitude was 171/2, but on Feb. 11 it had risen to 121/2, thus showing a hundred-fold increase in the light. There was a somewhat similar, but less intense, outburst in December 1929, the magnitude then rising from 17 to 131/2. Both the outbursts were shortlived, the additional light fading after a few days. It would seem that the cause of the outbursts must be sought in the comet's nucleus, rather than in the sun; but its nature remains a mystery. A somewhat parallel case was presented by the two successive outbursts of light of Holmes's comet, at its first apparition in 1892. That comet was, however, much nearer to the sun, less than three units.