PHENOMENA CONNECTED WITH COMETS.
The issue of "Collier's," the American weekly, and of the, 26th Jane, confined and interesting article by Edwin Fairfax Naulty upon the appearance of the new comet-like object, which was first observed on the 24th May by the Professor of Astronomy at Hobart College. After recounting the early evidences of the comet, the writer describes the phenomena that should follow its appearance: — "Two sets of light rays—one radiating from the sun, and the other, defracted sunlight, radiating from the gaseous head of a comet —meeting at angles varying from acute to obtuse are bound to produce results. The most obvious is an unsettled state of the weather. Prismatic effects, pulural shadows, mirages, and, the multiplication and intensication, of auroral and zodiacal lights are logical consequences. Other things—unaccounted for explosions, for instance--may follow. It must be remembered, that the heads of comets are gaseous bodies, which are, in effect, huge celestial | lenses. They condense, transmic, refract, Reflect, and reflect the radiance of tho sun's light. The earth's atmosphere tremendously affects the results, refractions, reflections, and other phenomena. "Comets' 'tails,' 'beards,' and 'wings,' have always been a great puzzle, but the explanation of these various appearances is, after all, veiy simple. The heads of comets are generally spherical bodies of qaseous consistency. Any one of these gaseous globes, travelling in space-in an orbit around the sun, acts as a great lens, and the 'tails' of comets are really lon>; shafts of transmitted, or slightly deflected, sunlight, passing through the outer ar.d more diffuse parts of a comet. THE HEADS AND TAILS OP COMETS. "The 'envelopes' of comets are really the meridian lines of high ill uminations, by the sun, of the outer portion of the comet. Where more than one 'envelope' is observed, this is due to variation in density of the gas in the head of the comet. Sometimes the gas lies in strata, and each strata reflects light of itself. If the comet's path is in line with the earth, or if their crbits agree, the 'envelope' of the comet will appear, not as a half circle, but as an elonged ellipse. A dime first held at right angles with the eye, and then turned until it is almost flat with the eve, will show this clearly, the milled edge of the dime r presenting the meridian line of light which, insofar as the comet or any body in the sol:.r system is concerned, always agrees with the equatorial line of high illumination of the sun.
"The 'beards' »f comets, so-called, are really light reflected back to the sun from the illuminated hemisphere of the comet. The 'wings' are really rays of light deflected from the sphere of the comet at the same angle at which they enter. The curved 'tails' of comets are explained by the fact that we see thes? fails' through the globular shell of at- j mc/sphere surrounding the earth, but only through 120deg, so that the atmosphere becomes a convex lens. You take a convex leri'i, place it in front of your eye, and look through it at a straight line; that straight lino follows the curve of lens and appears to be a curve equal to that of the lens. Whare comets' 'tails' appear curved, it is due to the tact that they lie alo i;; the lens, or with their axis in the same direction as the chord of the arc, but when straight lie obliquely, so that you look along the line instead cf ncross it, and the light ur line appeals straight. "Ihe new comet is a good example ot this, for its comalight comes to us, as I am writing this, at such an angle that its lines of light appears perfectly straight. When the new comet's head appears above the • horizon the comalight will appear fan-shaped, but with straight rays, later probably changing to curved rays.. The .larger the comaaphere, or head, of the cornet is, the more diffuse will be the light reflected by it; the smaller ( the comet, the sharper will be the pencil of light, modified in appearj ance in both cases by the obit ot the I comet, and its distance from the ! earth at the time we see it.
( '"Let me explain in this way. Suppose a great searchlight were mountI cd on tlid Capitol at Washington and !you stood at the White House, and the searchlight were turned at right angles; if it were a powerful condensing searchlight you would see a great, shaft of light stretching straight away in the heavens. Jf, un the other hand, you were standing halfway down Pennsylvania averue, the pencil of light woJij become a great cone-shaped ray, and if ycu again moved your position, so that you were closer to the searchlight, it would then appear as a wider cone, because you would only see a , portion of the light. VariationsVf this will readily explain variations in comalight from comets. "In considering ail effects of light it must be remembered that light is visible only bscause its speed is increased by deflection in our atmosphere. Without the atmosphere we could not see. The outer circumsphere of ouf atmosphere is globular; therefore, any section of ij: must be convex, thus affecting our vision of cel. atrial objects; Stars and planets, being , points and discn, are not affected; long raya of comalight are " And he summaries the phenomena that may be observed durirg the passage of the comet across the heavens in the following terms—among the phenomena, it will be observed, being one that has actually been recorded in Southland within the last few days:— "The explosion of great powder works, chemical laboratories, gat* tanks, and naphtha tanks, from unexplainable causes. Heavy rains arid fogs, followed by clear, blight weather, such as occurred in the
early days of June. Plural shadows of human beings and all dense objects. Prismatic fogs in which buildings will appaar to be in Hames. Vertigous shadows, which will flicker and waver. Mirages of ail magnitudes. Earth tremors. Prismatic illumination of either the earth's umbra or penumbra, or both, in which case great rainbow ray appear to rise from the horizon to the atmospehric nadir point by day. Auroras at avery point of the compass. An unsettled state of the weather, when the barometer does not agree with the apparent cloudiness."
Permanent link to this item
Hononga pūmau ki tēnei tūemi
https://paperspast.natlib.govt.nz/newspapers/WAG19090805.2.5
Bibliographic details
Ngā taipitopito pukapuka
Wairarapa Age, Volume XXXII, Issue 9560, 5 August 1909, Page 3
Word count
Tapeke kupu
1,061PHENOMENA CONNECTED WITH COMETS. Wairarapa Age, Volume XXXII, Issue 9560, 5 August 1909, Page 3
Using this item
Te whakamahi i tēnei tūemi
Stuff Ltd is the copyright owner for the Wairarapa Age. You can reproduce in-copyright material from this newspaper for non-commercial use under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International licence (CC BY-NC-SA 4.0). This newspaper is not available for commercial use without the consent of Stuff Ltd. For advice on reproduction of out-of-copyright material from this newspaper, please refer to the Copyright guide.