Nearly polar orbit around a planet, in which the satellite passes over any given point of the planet’s surface at the same local mean solar time. More technically, it is an orbit arranged so that it precesses through one complete revolution each year, so it always maintains the same relationship with the Sun.
Before studying the effects that the motions of the stars have had and will have upon the constellations, it is worth while to consider a little further the importance of the stellar pictures as archives of history. To emphasize the importance of these effects it is only necessary to recall that the constellations register the oldest traditions of our race. A knowledge has been obtained of their height above the ground during their flight and of the length of their visible courses.
Would a huge runaway sun, like Arcturus, for instance, make such an opening if it should pass like a projectile through the Milky Way?
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The fall of meteorites offers an appreciable, though numerically insignificant, peril to the inhabitants of the earth. Historical records show perhaps three or four instances of people being killed by these bodies. But for the protection afforded by the atmosphere, which acts as a very effective shield, the danger would doubtless be very much greater.
It has been calculated that on a clear night the total starlight from the entire celestial sphere amounts to one-sixtieth of the light of the full moon; but of this less than one-twenty-fifth is due to stars separately distinguished by the eye. If there were no obscuring medium in space, it is probable that the amount of starlight would be noticeably and perhaps enormously increased.
It is a singular fact that recent investigations seem to have proved that an event of this kind actually happened in North America — perhaps not longer than a thousand or two thousand years ago.
– William A. Miller
This leads us back again to the wonderful group of the Pleiades. All of the principle stars composing that group are traveling in virtually parallel lines. Whatever force set them going evidently acted upon all alike.
At the surface such a body is enveloped in a shell of relatively cool matter. Now suppose a great attracting body, such as another sun, to approach near enough for the difference in its attraction on the two opposite sides of the body and on its center to become very great the consequence will be a tidal deformation of the whole body, and it will lengthen out along the line of the gravitational pull and draw in at the sides
But serious questions remain. It needs, for instance, but a glance at the Triangulum monster to convince the observer that it cannot be a solar system which is being evolved there, but rather a swarm of stars. Many of the detached masses are too vast to admit of the supposition that they are to be transformed into planets, in our sense of planets, and the distances of the stars which appear to have been originally ejected from the focal masses are too great to allow us to liken the assemblage that they form to a solar system.
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As all the world knows, the sun, a blinding globe pouring forth an inconceivable quantity of light and heat, whose daily passage through the sky is caused by the earth’s rotation on its axis, constitutes the most important phenomenon of terrestial existence.
One of Barnard’s earliest and most excellent photographs includes two of them, both in the star-cluster M8. The larger, which is roughly rectangular in outline, contains one little star, and its smaller neighbor is lune-shaped — surely a most singular form for such an object.
It is an illuminating bit of astronomical history that when he was sweeping the then virgin heavens with his great telescopes he was accustomed to say to his sister who, note-book in hand, waited at his side to take down his words, fresh with the inspiration of discovery.
Just above the southern horizon of our northern middle latitudes, in summer, where the Milky Way breaks up into vast sheets of nebulous luminosity, lying over and between the constellations Scorpio and Sagittarius, there is a remarkable assemblage of coal-sacks, though none is of great size.
It is an illuminating bit of astronomical history that when he was sweeping the then virgin heavens with his great telescopes he was accustomed to say to his sister who, note-book in hand, waited at his side to take down his words, fresh with the inspiration of discovery.
One of Barnard’s earliest and most excellent photographs includes two of them, both in the star-cluster M8. The larger, which is roughly rectangular in outline, contains one little star, and its smaller neighbor is lune-shaped — surely a most singular form for such an object.
Is the Milky Way round in section like a rope, or flat and thin like a ribbon? The answer is not obvious, for we have little or no information concerning the relative distances of the faint galactic stars. It would be easier, certainly, to conceive of openings in a thin belt than in a massive ring