THE COMET, THE METEOR, AND THE MOON.

Otago Witness, Issue 2467, 26 June 1901, Page 26

THE COMET, THE METEOR, AND THE MOON.

A lecture on " The Comet, the Meteor. and Snow in the Moon," the fir»t of a series airangecl by the Trinity Wesleyan Literary Society, wa3 df In ored on Friday evening by thf Rev. P. W. Fairclough in Trinity Schoolroom. There was a moderate attendance, and Mr Walter Bull presided. The lecturer, iii the course of his remarks, said: Comets are known less by their appearance than by their orbits. The comet seen last month ft^elled in a hyperbolic orbit, and had ne\er visited the sun before, nor \va» likely ever to do so again. It must have been 5,000,000 or 6,000,000 of years under the sun's influence travelling towards him, and a similar time would' probably elapse before it escaped the sun's control. Comets are far from being rare. Last year four were seen, and three periodic comets clipped by unobserved, so that seven comets were known to approach the sun in 1900, which was a barren year. Of the four seen by astronomers one was expected, and another was found to have an orbit of six and three-quarter years. The other two were, like the recent one, visitors for the first time. There are probably millions of periodic comets. Those that are known appear to voyage out to the oibits of the great planets; those of six and an da-half years reach out to Jupiter. Halley's comet, with a period of 75 years, goes to the orbit of Neptune. Possibly, all those were at first visitors from space, and ths big planets by their attraction robbed the comets of their velocity and made them accept the sun's yoke. The visitors are probably far more numerous than the captured ones. No doubt the majority of these never come within human sight. It will not b& extravagant to say that 50 strangers curve round the mm every year at various distances. If, then, he has a supply always on hand sufficient for several millions of years, he must have a cremendous retinue of comets, and if each of the hundreds of millions of suns in space ha? a similar family comets must be far from rare. The tremendous extremes of climate endured by a comet that " brushes the embers from the sun," and then plunges into the absolute zero of space was described, and the mysterious development of the tail and its cause were discussed. Whether the tail is an electric or a sunlight phenomenon, or whether it was a material emission from the nucleus was debfted. There are reasons for supposing that tail matter may be winnowed out of a comet by numerous approaches to tb.e sun.. Comets

of .short period have little or no tail, while \ibitors extend appendages over 200,000,000 'of miles long. If this be levigating matter driven out of the cornet, it can certainly never return, so the supply muni become exhausted. The relation of comets and meteors was described. They are known to be associated in several instances by travelling the some orbit. They may have a common origin in the volcanic throes of our own and other sunn. Shooting stars become lumin- | ous at a height of 70 miles, and, starting downward, are dissipated at a height of 40 or 50 miles. They encounter the atmosphere at a velocity of, say, 70 miles per second, and become heated on the same prin- | ciple that a bicycle pump does — by the great ! cr ndensation of the air in front of them. I Meteors do occasionally reach the earth intact. One unbroken one brought frooti Nor- ! them Greenland by Lieutenant P^rry re- ' ccutly weighed many tons. Referring to , Professor Pickering's supposed discovery of snow on the moon, the lecturer gave several , reasons for not believing the mow theory — e.g., the absence of atmosphere on the moon, the power of the sun (the moon's day being 14 limei as long as ours), etc., etc.

The lecturer, who had a most att -ntive hearing and handled his subject most interestingly, was accorded a hearty vote of tl anks.