Interstellar cloud

“ The colors we see only faintly through our telescopes would present a magnificent sight when seen at close range, while constant changes would be taking place, as varied as the changes in the clouds flitting across a summer sky. Great cloud-masses drift hither and thither with enormous speed, driven by winds of hurricane force. ”

“ This mischievous radiance—which it is the chief merit of a solar eclipse to abolish during some brief moments—is due to the action of the atmosphere, and chiefly of the watery vapors contained in it. Were our earth stripped of its "cloud of all-sustaining air," and presented, like its satellite, bare to space, the sky would appear perfectly black up to the very rim of the sun's disk—a state of things of all others (vital necessities apart) the most desirable to spectroscopists. The best approach to its attainment is made by mounting a few thousand feet above the earth's surface. ”

“ Did an extinguished sun, flying blindly through space, plunge into a vast cloud of meteoric particles, and, under the lashing impact of so many myriads of missiles, break into superficial incandescence, while the cosmical wrack through which it had driven remained glowing with nebulous luminosity? ”

“ Using our anti-gravitating power, we rose once more into clear space, and then, beneath our feet, for hundreds of miles, we saw the vast clouds rolling around the mist-clad planet, much as, on an overcast day, the aeronaut sees the earth clad in cloud. ”

“ The earth in its revolution round the sun occupies every day a different place in the universe; if, therefore, a meteoric shower pass through our atmosphere at regular intervals, there must be at the place where the earth is at that time an accumulation of these small cosmical bodies, which, attracted by the earth, penetrate its atmosphere, are ignited by the resistance of the air, and become visible as falling stars. A cosmical cloud, however, cannot remain at a fixed spot in our solar system, but must circulate round the sun as planets and comets do ”

“ We cannot doubt that deep down below the visible surface of the planet—that is, the surface of its outermost cloud-layers—the fiery mass of the real planet. Outbursts, compared with which the most tremendous volcanic explosions on our earth are utterly insignificant, are continually taking place beneath the seemingly quiescent envelope of the giant planet. Mighty currents carry aloft great masses of heated vapor, which, as they force their way through the upper and cooler strata of the atmosphere, are converted into visible cloud. ”

“ The resulting mass may not be actually visible. The presence of the condensed particles may be indicated by nothing more than a slight whitening of the blue sky, or by the formation about the sun or moon of bright circles of light known as halos. If such a halo appears, it is generally a phenomenon of brief duration. Sometimes the circle breaks and becomes incomplete by the passing away of the thin patch of cloud, sometimes the cloud increases in density until the rings are destroyed. ”

“ Wasn't he the one who claimed to have discovered a sort of gaseous cloud in space? Our system was supposed to be approaching it; when it reached our atmosphere, it would prove a deadly poison to all life-forms on this planet. ”

“ The clouds we are so familiar with down here on the earth are produced by the heat of the sun, which beats down upon the wide surface of the ocean, evaporates the water, and raises the vapor up to where it forms the clouds. Heat, therefore, is necessary for the formation of cloud; and with clouds so dense and so massive as those on Jupiter, more heat would apparently be necessary than is required for the moderate clouds on this earth. Whence is Jupiter to get this heat? Have we not seen that the great planet is far more distant from the sun than we are? ”

“ We have to use the repulsing power on this too because travelling at the speed we are, those particles would really sandblast our ship," explains the scientist. "This cloud is produced mostly by satellites of Venus which are not like the Earth's moon. They have terrific dust storms blowing over them constantly which produce a dust belt around the planet half a million miles in width. ”

“ It was as if the general himself were rallying courage. “There is a giant radioactive cloud approaching the solar system from outer space at a terrific speed. The cloud covers an area roughly as big as Jupiter. Scientists have been plotting its trajectory with electronic instruments for a long time, and there is no doubt but that it will collide with the system if nothing is done about it. Life, of course, would be wiped out completely.”
Rob felt the horror of the statement clear to the marrow of his bones. ”

“ As the cosmical clouds which produce the meteors approach the sun in their wanderings from the far-off regions of space, they increase in density some million times, therefore the distance between any two meteors, only a few grains in weight, before the cloud begins to be condensed, may be upward of 40,000 miles. ”

“ We must recollect that the veil drawn between the cluster and the telescope was not a thin curtain; it was a volume of cometary substance many thousands of miles in thickness. Contrast, then, the almost inconceivable tenuity of a comet with the clouds to which we [Pg 358] are accustomed. A cloud a few hundred feet thick will hide not only the stars, but even the great sun himself. The lightest haze that ever floated in a summer sky would do more to screen the stars from our view than would one hundred thousand miles of such cometary material as was here interposed. ”

“ But look forward: the luminous cloud to which we are urging our flight has expanded, until what, at one time, was a mere patch of brightness, has now swelled into a mighty star cluster; myriads of suns burst into sight—we have traversed a distance which even on the wings of light would take hundreds of thousands of years, and have reached the confines of another Milky Way as glorious and mighty as the one we have left ”

“ As to the clouds—they are cleared away whenever we wish, by means of artificial thunder storms. Metallic conductors have been put in place up the sides of the lofty chambers, and at the proper heights are fixed with their poles pointing across the space, the positive on one side and the negative on the opposite. Heavy electric discharges are then made, the spark which is often one-fourth of a mile long traversing the cloud and speedily condensing it into rain. The observatory, I have spoken of, is too high to be often affected by clouds, but when the funnel is hazy, it can soon be cleared out. ”

“ Now, it is easy to perceive, that if all the regions of infinite space were filled either with self-luminous suns, or planets capable of reflecting light, or luminous nebulæ, or comets of gaseous consistency, at such distances as the Milky Way, or any other star-cloud demonstrates to be safe and practicable, we should see no blue sky at all; but the whole vault of heaven would present that whitish light resulting from the mingling of the rays of multitudes of stars, planets, and comets, which the Milky Way does actually exhibit. ”

“ These experiments open up many most interesting questions, but, unless it is to explain the extreme density and darkness of a thunder-cloud, they do not seem to play any important part in determining the forms to be assumed. Nuclei in sufficient abundance are probably always present at any height which can be reached by enough vapour to form a cloud. ”

“ Only artificial, and very high illumination would give the real effect of them,—painting cannot.
Enough, however, is here done to fix in your minds the distinction between those two species of cloud,—one, either stationary, [16] or slow in motion, reflecting unresolved light; the other, fast-flying, and transmitting resolved light. What difference is there in the nature of the atoms, between those two kinds of clouds? I leave the question with you for to-day, merely hinting to you my suspicion that the prismatic cloud is of finely-comminuted water, or ice, [17] instead of aqueous vapor ”

“ Although neither of them was unacquainted with interstellar space, it presents a spectacle that never fails to awe even the most seasoned observer: and no human being had ever before viewed the wonders of space from such a coign of vantage. Thus the two fell silent and awed as they gazed out into the abysmal depths of the interstellar void. The darkness of Earthly night is ameliorated by light-rays scattered by the atmosphere: the stars twinkle and scintillate and their light is diffused, because of the same medium. ”

“ Purity of colour in [64] these rings is an indication of uniformity in the size of the particles. When the moon is shining through a sheet of alto-stratus, which thins off to one edge, very beautiful effects may often be noticed, and the change from the colourless blur, when a thicker part of the cloud is interposed, to the brilliant colours of the corona formed by the thinner edges is very striking. Similar phenomena are shown almost equally well by any of the alto clouds, but cirrus thin enough to produce a coloured corona will generally produce a halo. ”

“ They will be sufficiently tangible to slow the speed of the planets perceptibly upon their orbits. Terrific planetary disruptions will follow in the form of earthquakes and volcanic eruptions, and entire oceans will turn to steam and bury each world in a dense cloud blanket. Temporarily, the nova will outshine every star in its neighborhood and will loom visible countless light years distant. ”

“ Interplanetary space we have the radiations of the sun to depend upon, and they are decidedly sufficient, usually superfluously so. But in the infinite depths of interstellar space, there is only darkness and a perfect reservoir for radiations. There would be continuous cooling by radiation, and no sun to warm the ship. I could understand how the ship might carry enough matter to warm it for one hundred years, but in sixteen hundred years so much energy must be radiated that the entire mass would not suffice. Nothing short of an entire planet would be sufficient. ”

“ The Greater Cloud is much brighter to the naked eye than the Lesser, and it is much more complex and interesting in the telescope. It contains, moreover, the wonderful Looped Nebula, of which we have already spoken.
Both Clouds consist of gaseous nebulae and star-clusters on a background of vague nebulosity and crowds of almost indistinguishable stars. But the white nebulae shun the Clouds, just as they shun the Milky Way. ”

“ When the depths of the heavens are explored with a powerful telescope a number of strange cloud-like objects are brought into view. It is startling to consider that if the eye of man suddenly acquired the light-gathering power of a large telescope, and if at the same time all the single stars disappeared, we should see on the celestial vault a display of the mysterious objects called nebulæ or star-clouds exceeding in number all the stars which can now be seen on the darkest night in winter. ”

“ It is permissible, therefore, to neglect the trifling irregularities and agglomerations in the distribution of star-matter, and to assimilate the entire stellar universe to a vast cloud of cosmic dust at relative rest, everywhere of the same density. It is then found that for this cloud of dust to maintain a permanent, stable configuration, the time direction of the universe as a whole, for an observer who is non-rotating with respect to the stars, must be straight. ”

“ During the whole of its rapid and wonderfully even revolution round the earth, the great cloud was extending itself less conspicuously towards the north and south, and many scattered observations in the temperate zones afford evidence that the sifting out of heavier particles continued without interruption, and that these, in sufficient quantity to produce moderate afterglow, were carried by the anti-trades and other elevated currents to great distances. ”

“ On the contrary, it is well known to astronomers that the sky is, on the whole, clearer and freer from clouds after midnight than in the earlier hours of the night—a circumstance which is particularly unfortunate for the amateur star-gazer, who has to be up and about at the same time as the rest of the working world. ”

“ The upper edge of the cloud is luminous, sometimes brilliant and irregular. The lower part is frequently dark and thick, with the clear sky appearing between it and the horizon. Streams of light shoot up in columnar forms from the upper part of the cloud, now extending but a few degrees, then as far as the zenith, and even beyond it. Instances occur in which the whole hemisphere is covered with these coruscations; but the brilliancy is the greatest, and the light the strongest, in the north, near the main body of the meteor. ”

“ It is an emblem of the universe according to the ancient doctrine, showing us how the visible may issue from the invisible, and return again thereto; that a drop too small for the unassisted eye to see may be the representative of a world. The spontaneous emergence and disappearance of a cloud is the emblem of a transitory universe issuing forth and disappearing, again to be succeeded by other universes, other like creations in the long lapse of time. ”

“ It was dark, and therefore probably represented an opening in a great cloud-layer by which a lower or inner layer was brought into view. (For though the planet's real globe may be so intensely hot as to emit a great deal of light, it is probable that most of the light so emitted is concealed by the enwrapping cloud masses, and that the greater part of the light we receive from the planet is reflected sunlight; so that the inner cloud-layers would be the darker.) South estimated this spot as about 20,000 miles in diameter. ”

“ Whether this ring be continuous, and the meteoric masses strewed along the whole course of the path of the original comet, or whether the individual meteors, as in the November shower, have not filled up entirely the whole orbit, but are still partially in the form of a comet, is, in the transformation of a cosmical cloud through the influence of the sun, only a question of time; in course of years the matter composing a comet which describes an orbit round the sun must be dispersed over its whole path ”