COMETS AND THEIR TAILS

New Zealand Tablet, 14 April 1910, Page 573

COMETS AND THEIR TAILS

Halley’s Comet was seen for the first time in Gore on Saturday morning a few minutes before break of day. In view of the presence of this long-expected visitor, the following particulars regarding comets, taken from a Home publication, will be of interest: Although scientists have not yet discovered exactly what a comet consists of, their observations have led. to some remarkable revelations. A comet may be described, as a definite point of nucleus, surrounded by light, with a luminous train preceding or following. The general opinion of astronomers seems to be that the point is possibly solid, or at any rate condensed, the tail consisting of minute particles floating in a gaseous envelope, and the whole being whirled round the sun at a rate which in some cases reaches as much as 370 miles a second. Halley’s comet is a small one as compared with others which have been observed in previous years. The tail is said to be close on 26,000 miles in length, but in 1882 —the last occasion on which a bright, naked-eye comet was seen in England— was estimated that that comet had a tail which extended in space to the vast distance of 200,000,000 miles from the head, though, owing to foreshortening, it did not appear to be that extraordinary length. The tail was strongly forked, and a singular and puzzling feature of the comet was that a small cone, or envelope, computed to he 4,000,000 miles in length, also extended towards the sun'. Sir W. H. M. Christie, the Astronomer-Royal, has collected some striking facts with regard to comets’ tails. He says that the tail of the comet of 1861 was 40,000,000 miles long; that of 1680 had a tail of 60,000,000; that of 1811, which was visible for 17 months, over 100,000,000; while the visitor of 1843 showed a tail in the evening twilight of 65deg, or about 200,000,000 miles in length, which exceeds the diameter of the earth’s orbit. Not the least amazing feature of these bodies, is their wonderful velocity when near the sun. The comet which Newton saw in 1680 was travelling at the rate of 250 miles a second, and that of 1843 at 370 miles a second. The earth in its orbit moves at 18J miles per second.

Apropos of the asertion frequently made that should °' ie ■ °u f these comets touch the earth it would mean the end or the world, it appears that already we have passed through a comet’s tail. Sir W. Christie thinks that in 1861 we passed through the outer part of a comet, particles of which appeared as a shower of falling stars; while other scientists also affirm that we have come into contact with comets, and that there is not the slightest need to worry or insure against them in view of damage.