ENCKE’S COMET

Stratford Evening Post, Volume I, Issue 173, 2 July 1931, Page 4

ENCKE’S COMET

A REGULAR VISITOR

Encke’s comet, the reappearance of which has been reported, although not a spectacular celestial visitor, is interesting in that it has the shortest known cometary period, going round the sun once in every three and a-quarter years. It passes within 31 million miles of the sun each time it comes round, this being a closer approach than any other comet, and for this reason it is usually visible. But as it is only of the ninth magnitude, a small telescope or field glasses will be required if it is to be seen. It is now near the star Procyon in the western sky, and can be seen more clearly in the Southern Hemisphere than in the Northern.

Most comets are named after their discoverers, but not so Encke’s. It was first seen in 1795 by a Parisian astronomer. In November, 1818, Pons, whose name is borne by another comet, observed it for 40 days. J. F. Encke, the celebrated German astronomer, then made this comet his special study. He accurately calculated its orbit, and his prediction of its return in 1822 was correct. In view of the great amount of mathematical work done by Encke on this comet it was agreed among astronomers to give it his name, Encke’s comet has been observed every time it has returned since 1818, a distinction shared only by Halley's comet. Other comets go missing or are so situated that they cannot be observed, but both Encke’s and Halley’s comet (the latter having a period of nearly three-quarters of a century) have been picked up by astronomers each time they have come round. Of course, how much longer Encke’s comet, or Halley’s, or any other for that matter, will continue its journey round the sun, no one knows. Something may happen to disintegrate it or to cause it to fly away into space. But it would seem as if it is getting tired, for each time it comes round it is 21 hours later than before. Expert astronomers are agreed that this- is so, but they are not agreed as to the cause.