Planetary transit

“ Today, we are witnessing the beginning of a new era in space transportation with the development of commercial space vehicles.
As our cities grew, transit systems evolved to provide affordable, convenient urban transportation. The 20th Century brought the automobile, truck, intercity bus, rapid rail systems, and an expanded road system that now includes thousands of miles of interstate highways. ”

“ Consequently there would be at least two transits of Vulcan [Pg 45] every year, and there would generally be four transits; the average number of transits would be about eleven in three years. With a wider orbit and a greater inclination transits would be fewer; but even with the widest orbit and the greatest inclination that can possibly be allowed, there would be at least one transit a year on the average. ”

“ Interesting, though of somewhat rare occurrence, are the transits of Mercury, when the planet comes between us and the sun, and passes as a black circular dot across the bright solar surface. The first occasion on which such a phenomenon was observed was November 7, 1631. The occurrence of this transit was predicted by Kepler four years in advance; and the transit itself was duly observed by Gassendi, though five hours later than Kepler's predicted time. ”

“ The consequence is that when another eight years have elapsed, the planet passes a little above the sun or a little below the sun, and thus a third occurrence of the transit is avoided for more157 than a century. ”

“ Obviously, if the planets by their transits effect anything whatsoever, the double transit of major planets must have [Pg 133] a correspondingly greater effect. The careful student of Astrology will institute a number of tests in order to find what effects are due to the combined action of the planets when in conjunction at transit, and also when in opposition or quadrature. The chief points to be noticed in connection with the transits of the planets are the Midheaven, Ascendant, and the places of the Sun and Moon, as already mentioned in Chapter II of this section. ”

“ A transit is the passing of a primary planet across the Sun, or of a secondary planet (i.e. satellite) across its primary, whilst an occultation is the concealment of a star by the Moon, or of a secondary planet (i.e. satellite) by its primary. A little thought given to this definition will make it [236] clear that a transit is essentially the same in principle as an eclipse of the Sun by the Moon—one body comes in front of another, and the former conceals in succession parts of the latter. ”

“ When I meet the engine with its train of cars moving off with planetary motion,—or, rather, like a comet, for the beholder knows not if with that velocity and with that direction it will ever revisit this system, since its orbit does not look like a returning curve,—with its steam cloud like a banner streaming behind in golden and silver wreaths, like many a downy cloud which I have seen, high in the heavens, unfolding its masses to the light,—as if this travelling demigod, this cloud-compeller, would ere long take the sunset sky for the livery of his train ”

“ A peculiarity distinguishing this method from the former is that the observers must have a station whence the whole transit can be seen; for practically the place of Venus's track can only be ascertained satisfactorily by timing her passage across the sun's disc, so that the beginning and end must be observed and very carefully timed. This is to some degree a disadvantage; for during a transit lasting several hours the earth turns considerably on her axis, and the face turned sunwards at the beginning is thus very different from the face turned sunwards at the end of transit. ”

“ Occasionally Mercury passes at inferior conjunction between us and the disc of the sun, appearing like a black spot against the sun, and thus makes what we call a transit. Because the planet is so small, his transit across the sun cannot be seen with the naked eye; but it is an interesting phenomenon to those who can view it with a telescope, though, apparently, astronomers do not regard it as having any great scientific importance. ”

“ Half way across they suddenly they feel a deep, thrumming vibration from space. Looking up, they see a gigantic, pancake-shaped, interplanetary space liner moving in above the parking block. Interplanetary space liners are not like the little single-seaters, family wagons, or even the big bus line and ferry space ships that carry folks like Stobey and Slutter from their homes to Super-Rock. Space liners are much larger than the biggest ocean liners that sailed the seas of Planet Earth long ago, and you've seen in history books how enormous they were. ”

“ Besides the advantage of having a dial-face like the sun’s on which thus to determine positions, the transit method deals with Venus when at her nearest, or about 25 million miles from us, instead of the sun at his greater distance of from 901⁄2 to 931⁄2 millions of miles. Yet we do not get the entire advantage of this relative proximity of Venus. For the dial-face—the sun, that is—changes its position too—in less degree than Venus changes hers, but still so much as largely to reduce her seeming displacement. The sun being further away as 92 to 25, is less displaced as 25 to 92. ”

“ The enormously-developed system of intercommunication made transit, even for very large numbers of men and between very distant points, rapid to a degree undreamt of in the present century.
Trains could travel at two hundred miles an hour along the hundreds of quadruple lines which covered the Continent with their gigantic network, aerial cruisers could fly at more than twice this speed, and squadrons of submarine battleships could cleave their silent and invisible way through the ocean depths at a hundred and fifty miles an hour. ”

“ Yet the prevalence of legends regarding flight, existing in the records of practically every race, shows that this form of transit was a dream of many peoples—man always wanted to fly, and imagined means of flight.
In this age of steel, a very great part of the inventive genius of man has gone into devices intended to facilitate transport, both of men and goods, and the growth of civilisation is in reality the facilitation of transit, improvement of the means of communication. ”

“ In slightly over two decades, man has ingeniously explored five distant planets—and two dozen moons. We have seen their weather and surfaces, landed on some, probed the atmospheres of others, and listened to their radio noises.
Under the planetary exploration program of the National Aeronautics and Space Administration, the Voyager Mission, begun in 1972, was designed to explore Jupiter, Saturn, their satellites, rings, magnetic fields, and interplanetary space. Two automated, reprogrammable spacecraft, Voyagers 1 and 2, were launched in late summer of 1977. Their goals: the outer planets. ”

“ The Interplanetary Suburban Line runs trains every half hour on that day. You will find there a complete working model of the old satellite of the Earth, which, before it was destroyed, furnished this planet light at night through the crude medium of reflection. ”

“ Such an exhaustive journey requires the special powers of a primary seconaphim of transport endowments. Transporters take on energy for flight while in transit and recuperate personal power at the end of the journey.
Even on Salvington ascending mortals do not possess personal transit forms. Ascenders must depend upon seraphic transport in advancing from world to world until after the last rest of sleep on the inner circle of Havona and the eternal awakening on Paradise. Subsequently you will not be dependent on angels for transport from universe to universe. ”

“ The various assistants are now in training at Greenwich, Poltava, and Washington, with the very instruments which they will use on the expeditions.
At Washington and Poltava an apparatus for the representation of the transit is in use. A disk representing Venus is caused to travel over an illuminated space which is representative of the sun, and the circumstances of the transit are then observed.
In this way it is hoped to obtain an idea of the personal error of each observer in watching contacts, so that, in reducing the observations of the transit, all personality may be eliminated. ”

“ Now a great fleet of cargo carriers from Mars, Venus and Earth came up, and with them came wrecker ships, capable of picking up on their powerful attractor beams an entire million-ton passenger-freight liner—great liners themselves, all equipped with attractor beams. Soon they were all using their power to bring the planet back to its normal speed. It did not take the ships of that mighty fleet, many specially designed for heavy listing and towing, many designed for tremendous loads, very long to bring the planet back to its age-old orbit. ”

“ The planets, however, are closer as you approach the sun, just as on a railway the stations become more numerous as you approach the metropolis. In our cometary vehicle, the speed is always increasing, so that, although slow as a railway train at first, it soon acquires immensely greater speed as it rushes on towards its distant goal. The comet of Halley, though starting so far beyond the verge of the system, takes only about forty years to reach the sun. The railway train, going always at the same rate, would take 10,000 years from the remotest orbit of the system to the centre. ”

“ By an illusion familiar in the case of railway trains, it seemed to us that the car was stationary, and the planet rushing towards us. On it came like a great shield of silver and ebony, eclipsing the stars and growing vaster every moment. Under the driving force of the engines and the gravity of the planet, our car was falling obliquely towards the orbit, like a small boat trying to cross the bows of an ironclad, and a collision seemed inevitable. ”

“ We may illustrate the matter by supposing the planet to be running like a railway engine on a track which has been laid in a long elliptic path. We may suppose that while the planet is coursing along, the shape of the track is gradually altering. But this alteration may be so slow, that it does not appreciably affect the movement of the engine in a single revolution. We can also suppose that the plane in which the rails have been laid has a slow oscillation in level, and that the whole orbit is with more or less uniformity moved slowly about in the plane. ”

“ According to the law of railroads, as will be found in theory and practice, no railroad for despatch of business, speed, and safety, should rise more than from twelve to fourteen feet per mile. The law of gravity, propulsion, and speed, will be found to be obstructed about one hour in every two feet rise, in twenty miles; so that the speed of a steam engine that could perform thirty miles an hour on the level, will be reduced to less than five miles per hour, upon a rise of twenty feet per mile. ”

“ Evidently the question of inter-planetary travel is coming to the front. In your article you suggest that a locomotive car, that is to say, a car able to propel itself through what we, in our ignorance, call empty space, though, in reality, it is chock-full, and very 'thrang' as the Scotch say, might yet be contrived, and even worked by energy drawn from the ether direct. ”

“ Let us, therefore, take the motion of a rail-way car as the most rapid with which we are familiar, and apply it first to the planetary spaces, and then to the vast interval that separates these nether worlds from the fixed stars. A rail-way car, travelling constantly night and day at the rate of twenty miles per hour, would make 480 miles per day. ”

“ Supposing, finally, that our train were started from the sun, and made to run straight out to the known boundaries of the solar system, that is to say, as far as the orbit of Neptune, it would take over 5000 years to traverse the distance.
That sixty miles an hour is a very great speed any one, I think, will admit who has stood upon the platform of a country station while one of the great mail trains has dashed past. ”

“ The present transit is the fourth which the Observatory has possessed, and its three predecessors, known as Halley's, Bradley's, and Troughton's, respectively, are still preserved and hang on the walls of the transit room, affording by their comparison an interesting object-lesson in the evolution of a modern astronomical instrument.
The watcher who wishes to observe the passing of a star must note two things: he must know in what direction to point his telescope, and at what time to look for the star. ”

“ In this century, as exploration has become more and more dependent on advances in technology, the scientific element has attained increased prominence. The greatest legacy of the NASA Planetary Program is the knowledge it has provided of the other worlds that share our corner of the universe.
Despite the central role of science in motivating missions to the planets, specific scientific considerations are not dominant during most of the development of a mission such as Voyager. The problem of building a spacecraft and getting it to the outer solar system is too demanding. ”

“ In this way then the transit instrument enables us, having true time, to determine the right ascension of a heavenly body as it transits the meridian, and, knowing the right ascension of a heavenly body, we have only to watch its transit in order to know the true time; so if the observer knows at what time a known star ought to transit, he has an opportunity of correcting his clock. ”

“ In this are plans for groups of stars for R.A. (the Transit Instrument being the only one finished) : order of preference of classes of observations: no reductions to be made after dinner, or on Sunday: no loose papers: observations to be stopped if reductions are two months in arrear: stars selected for parallax.—The reduction of transits begins on Apr. 15th. On May 15th Mr Pond sent me some moon-transits to aid in determining my longitude.—Dr Young, in a letter to me of May 7th, enquires whether I will accept a free admission to the Royal Society, which I declined. ”