CHAPTER XIV
MARS AND SATURN
The Red Planet of Mars, the God of War
Diameter—4230 miles
The orbit of the little planet Mars, 141,000,000 miles from the sun, encompasses the orbits of Earth, Venus and Mercury, and forms the boundary line between the four inner planets and the planetoids or minor planets. Beyond the planetoids are the four great planets, Jupiter, Saturn, Uranus and Neptune.
The orbit of Mars is very eccentric, more eccentric, in fact, than any other planet in the solar system with the exception of Mercury. At its nearest approach to the earth's orbit it is only 35,000.000 miles away, while at its furthermost point it is distant 62,000.000 miles. The two planets, however, when at different points in their orbits, may be over 200,000,000 miles apart. This eccentricity in the orbit of our neighbor Mars causes it to differ in brightness as we see it shining as a star, for, although it is always large and beautiful, at its nearest approach to the earth it shines with more than tenfold the brilliancy of a first magnitude star. At such a time its fiery light attracts the attention of everyone. Such extreme increase in light can only occur in the months of August and September and then only about every fifteen years. This was a much heralded astronomical event of the year 1924, when the two planets were closer together than any other time during more than a hundred years. However, Mars was low in the sky and not in such a good position for observation as it will be two years from that date when at a higher altitude, even though it will be at a greater distance from the earth. During shorter periods at intervals of two years and two months, the earth passes between Mars and the sun; Mars then shines in our night-sky as an especially red and lovely star with a well-illumined face just right for observation.
Mars is a much smaller globe than either the earth or Venus, but it is larger than the planet Mercury._-_figure_151.jpg)
MARS, SHOWING SURFACE MARKINGS AND POLAR CAPS.
Photographs by the Mount Wilson Observatory. Its diameter of 4230 miles is only a little more than half that of the earth, although its period of rotation is almost the same, the earth gaining by two-thirds of an hour. Its day therefore is only about 40 minutes longer than ours. The seasons of Mars are twice as long as ours, and its year equals 687 of our days, or 669 of its own.
The atmosphere of Mars is very rare and thin, more rare and thin than that surrounding the peak of Mount Everest, our highest mountain. Being less than one-fourth as dense as that found on the earth, one may see through it easily and discern the permanent markings on its surface. The first thing one notices through a telescope is the ruddy color of its surface and the dark belt across the equatorial regions. The ruddy color is presumed to be the characteristic color of its soil, five-eighths of which is in a desert condition; there are also regions of other colors which are subject to change, and a white cap marking either pole.
The two white caps about the poles increase greatly during severe months of winter and vanish to small spots during the warmth of the Martian summer. These are the reservoirs of moisture for the planet. A series of photographs illustrating the phenomenon of the increase and decrease of these caps is very interesting, for at the height of the Martian winter, for instance, the north polar cap extends to the temperate zone while during the summer it dwindles until it is but a tiny patch a few hundred miles across. As the polar caps melt, they are bordered by a blue belt and this blue belt is only visible as the brilliant caps disappear. Judging from the same phenomena which are manifest on our earth, these polar caps were supposed to be snow. Through the aid of the spectroscope, they are now known to be snow.
The ruddy areas on Mars are interpreted as desert regions—great unfertile tracts of land but little affected by changes in climatic conditions, while the large irregular dark or blue-green regions are regarded as marshes or areas covered with vegetation, since they invariably grow darker during the Martian summer and reveal themselves in massed colors changing from the initial blue-green to ocher and finally to chocolate-brown. These changes follow the melting of the polar caps and each hemisphere undergoes the change in turn. Mars, however, is best known and famous for the theory of its so-called "canals."
The "canals" were first observed by Schiaparelli, the distinguished Italian observer, in 1877. Schiaparelli thought that the dark irregular areas were oceans and that they were connected by these narrow streaks which he called "canale" or "channels." Unfortunately the word was not translated as "channels" but as "canals," which implies artificial construction, and this latter does therefore not convey the idea which the astronomer sought to convey. These black lines, or "canale," are generally straight and although spoken of as narrow, must be at least 12 miles in width and from a few hundred to three or four thousand miles in length. Starting from points near the polar caps, they follow the arcs of great circles, proceeding to what seem to be centers in the middle of the continent where, most surprisingly, they meet other lines which have come to the same spots. Schiaparelli says that "every channel opens at its end either into a sea or into a lake or into another channel, or else into the intersection of several other channels." "None of them as yet have been seen cut off in the middle of a continent, remaining without beginning or without end. . . . by preference they converge toward the small spots which we have given the names of lakes." These lakes are sometimes several hundred miles in diameter, although many are very much smaller.
The late Dr. Lowell, splendidly equipped with an observatory 7000 feet above sea-level in the clear air of Flagstaff, Arizona, maintained that each "canal" marked the route of a waterway, and that the visible mark is not the "canal" itself, but a broad band of vegetation irrigated from a narrow channel. He studied and mapped 522 of these canals, 56 of which were double. He also mapped the "lakes" which he called "oases." Dr. Lowell wrote a very interesting book on "Mars as the Abode of Life" as a result of his observations. He explains the "strips of vegetation" in this manner:
Since Mars is fast approaching a desert condition, there is a great scarcity of water, the only reliable source of supply coming from the melting of the snows at the polar caps. With the advance of spring the white caps begin to recede and a dark band appears around the edge. The water thus formed then flows away from the poles over the flat, dry surface, collects in the greenish areas (which are probably marshes) and from there is led into the canals. These canals do not begin to appear until the snows begin to melt and are always in the same position each season. The land is then moistened with water, the process starting near or around the melting polar caps and gradually moving down toward the equator. This water takes about 55 days to reach the equator, vegetation springing up along the way. At the end of the season, the fresh green withers and dies down. The spots, or oases, always connected by a canal to the rest of the dark area, appear and disappear, like the canals, with seasonal changes. These start faint in tone as large as they are to be, then darken throughout.
Since the vivifying water advanced from the south pole toward the equator and also toward the equator from the north pole, Lowell concluded that it must have some propelling force behind it, at least in one direction. This presupposes the directing influence of an intelligence.
Accepting the theory that Mars is inhabited by intelligent beings, it is presumed that the water resulting from the melting of the snow caps is consciously controlled and turned over certain designated portions of its surface, otherwise the tremendous floods "would prove more of a curse than blessing." The picture is one of a high order of intelligent beings realizing that their water is gradually disappearing and that their planet is rapidly becoming a desert, and who are struggling heroically to prolong its life. There are many objections to this theory, but at least it is an interesting hypothesis presented by a noted astronomer who possessed a splendid telescope erected in the clear air of Arizona, and who spent his life in a study of this planet.
The entire surface of Mars is about equal to the land surface of our earth. The density of the planet is only 73% that of the earth and the force of gravity on its surface is 35% as great as on the surface of our world. The lesser force of gravity, also the lower temperature and rare atmosphere, would all have their influence on any life found on Mars with the result that beings found there might be constituted physically in a very different way from ourselves. The temperature of Mars was computed lately at the Mount Wilson and the Lowell observatories and the results obtained at the two observatories were in excellent agreement. Although it was found to be 94 degrees below zero at one pole and 96 degrees below zero at the other pole, the average temperature on other parts of the planet during the brightest parts of the day averages between 40 to 60 degrees F. This would be a livable temperature for life as we know it, although another fact is commented upon which might cause curious complications. Since the blanket of air surrounding the planet is not of sufficient thickness to hold the heat on the planet, most of it may escape during the night-time, thus causing the temperature to drop to over 112 degrees below zero. If intelligent life wished to survive from day to day it would have to hibernate, perhaps in heated underground galleries, during the night half of its existence. The question as to whether or not there could be life on this planet has been hotly disputed by astronomers for years. It is certainly one of the most interesting aspects of astronomy to the public at large. It is often argued that since Mars is smaller than the earth it must have cooled down millions of years before the earth reached a similar stage, and that its organic life must therefore be proportionally farther advanced. Others have contended that it is past the age where it would be able to support life of any kind.
Professor W. H. Pickering has advanced a new speculative theory called "The Theory of Aerial Deposition." According to this theory the major canals are natural marshes fed by storm laden air currents. These marshes furnish Mars a substitute for our oceans. Without them "the water evaporated from the summer pole would find its way too rapidly, through the natural general atmospheric circulation of the planet, to the southern polar regions, where, wrapped at this season in the long winter night and subjected to the cold of space, it would quickly be withdrawn from further use in support of vegetal and perhaps animal life. The function of the so-called canals or marshes in the economy of the planet is in short to furnish a substitute for our oceans, and to furnish by evaporation during the Martian summer a steady and continuous supply of water after that derived from the northern snows has appreciably diminished." The above is quoted from a report on Mars by Professor Pickering in the January number of Popular Astronomy, 1918. Professor Pickering believes that the "canals" "are either bands of moistened soil or vegetation growing on moistened soil" and that they cannot be anything else "for we know of no solid in the mineral world that darkens and then fades out in the sunlight." He does not think that the major canals are necessarily the work of intelligent beings, but they do serve the purpose of furnishing the northern hemisphere with a supply of water in the form of natural marshes during the long northern summer until the southern polar cap starts to melt at the coming of the autumnal equinox.
Professor Pickering, who has written a book called "Mars," gives the following interesting information as to how the planet appears through the telescope at Flagstaff: "We may examine the moon some night through a small opera-glass. The sharpness and amount of detail visible in the two cases will be similar, although the appearance of the two bodies is quite unlike."
General public interest in Mars is probably keener than in any other planet and since the great event of August 23rd, 1924, when Mars shone like a lantern in the sky, this interest will probably grow greater than ever. This small matter of 34,648,000 miles—not much over a third of the distance to the sun away from us—is almost as near as the earth and Mars will ever approach one another.
An association of observers interested in Mars who are stationed in different parts of the world has recently been formed. All parts of the planet are now kept under inspection and regular reports are sent to a central bureau which publishes the results in an astronomical magazine.
The Satellites of Mars
The following story is often related in connection with the satellites of Mars: Many years before the satellites were discovered, Swift, in "Gulliver's Travels," described the little planet as having two moons, one of which flew across the Martian sky three times a day! The thing seemed absurd, for never during all the explorations of the solar system had a moon been found which behaved in such an erratic fashion. Nevertheless, in 1877. Professor Asaph Hall, of Washington, discovered two tiny attendants to the planet of the War-god weaving "like golden shuttles" around the Martian orb, and one of these made three revolutions in its orbit while the planet itself turned once on its axis! Thus the month of this surprising moon is less than eight hours long.
This little rapid-transit moon flies only 3700 miles above the planet's surface, and, on account of the curvature of the globe it would not be visible beyond 69 degrees of latitude on each side of the equator. As seen from Mars, it rises in the west and sets in the east, changing from new to full one and a half times every night! With the constantly recurring metamorphoses of this tiny moon, which is scarcely 7 miles in diameter, and its most exceedingly rapid flight, it would seem that there would be some reason in naming it Phobos (Fear), after one of Mars' attendants. On account of its nearness to the surface of Mars, Phobos would appear to a Martian about the same size as our moon does to us.
The other moon, which was named Deimos (Terror), is about 14 miles in diameter and is 12,500 miles from the planet. Its period is also very short, being only 30 hours and 18 minutes. Since this period is only a few hours more than the rotation period of Mars, the moon moves very slowly across the sky, remaining continuously above the horizon of any given place on the planet for more than 60 hours. It has been computed that these two small moons would cause 1400 eclipses of the sun a year, as seen from Mars. They are the smallest objects visible in the sky, as seen from earth.
Our month of March, as well as this fiery-hued planet, was named after the War-god. Since Tuesday was also named after the War-god, it might be well to mention here how the other days and months obtained their names.
In the early days of Astrology, a "science" which was based on legends and myths, the names of the five planets then known were given to the days of the week. Apollo, the Sun-god, gave his name to Sunday, and his sister, Goddess Diana, to Monday, and these two days retained their names, but the days which followed those named for the sun and moon later became Germanized, as it were, or the names of the originally imported gods translated into those of the Germanic divinities. Thus the name of the Northern Sword-god Tyr, who resembles the Roman War-god Mars, was given the day of the week held sacred to Mars, now known as Tuesday, or Tiu's day, Mercury's day became Wodan's or Wednesday, Jove's day was called Thor's or Thursday, and the day of Venus transformed into Friday, the day of Freya, the wife of Wodan. The day of Saturnus, retained under this name in some northern tongues, became a langardage, or a bathing day, in others. As for the months—October and February were names derived from Roman festivals; a horse named October was sacrificed to the War-god Mars during this month, while February derived its name from the Roman festival Februalia, from februare, to purify. April, meaning Aprilis, from aperire to open, obtained its name because it was the season when the buds began to open. September (septem, seven), November (novem, nine), and December (decern, ten) were the 7th, 9th and 10th months of the year of the Roman calendar when the year consisted of 10 months. January was named after Janus, the porter with the double head which enabled him to look back into the past and forward into the future; May after Maia, one of the Pleiades; and June, after Juno, Queen of the gods and the Goddess of Marriage. Quintilis, the 5th month of the Roman year, which began in March, was named July in honor of Julius Cæsar, while the 6th month, which was originally styled Sextilis, received its present name, August, from the Emperor Augustus.
The Ringed Planet of Saturn, the God of Time
Diameter—73,700
Although Jupiter is the largest planet and Mars the most interesting planet, the planet Saturn, as seen through a large telescope, is the most uniquely beautiful creation that man has ever beheld. The spectacle of a huge silvery ball surrounded by an equally huge and silvery ring suddenly disclosed in the midst of the darkness, is such an astounding surprise that one can never forget the strange sensations experienced when first beholding it.
Saturn moves very slowly through the sky, traveling on the average only about one degree a month and spending two or three years in each zodiacal constellation. This is because its pathway lies millions of miles beyond that of Jupiter's, and is so large that it takes the planet 29½ years to complete its circuit around the sun.
Saturn is believed to be composed mainly of gases and vapors or to be at least in a fluid condition with no solid crust. Its density is less than that of any other planet in the solar system, being only 0.70 as compared with water as unity. This is only about one-half as great as the density of Jupiter, which is somewhat greater than that of water. The weight of the earth is five and one-half times that of water. If the earth and Saturn were two balls immersed in an ocean large enough to hold them, the earth would sink like a ball of metal while Saturn would float like a ball of wood.
A white belt may usually be seen near the equator of Saturn and curious pale gray caps cover both the poles. Between these are faint colors and other dim belts. Its colors as markings are not as pronounced as in the case of Jupiter, on which they are far more distinct as this latter planet is 400,000,000 miles closer to the earth. The mysterious gray color of the caps at the poles of Saturn remain an enigma and the spectroscope shows that Saturn contains some substance which has not yet been identified.
Saturn's equator is inclined to the plane of its orbit at an angle of 27 degrees—a direct contrast to the axis of Jupiter which is almost perpendicular. This would cause Saturn to have very marked seasonal changes and very long seasons for one of its years is equal to almost 30 of ours.
Day and night on Saturn are very short for this huge planet turns completely around in 10¼ hours. With only 5⅛ hours of daylight (and Saturn receives only 1⁄90th as much light per unit area as that received by the earth), one would hardly get up before it was time to go to bed. But perhaps the future Saturnian will be so constructed that he does not have to spend so many hours in sleep, or perhaps, as in the Golden Age when the god Saturn ruled on earth and the needs of man were brought forth without labor, this length of day would be quite enough for general entertainment. Again, they might be such quick-witted creatures that they could accomplish a thing while we were thinking about it, or, yet again, they might not care to slave all their days in order to indulge in such foolishly complex lives as we do here and 51⁄8 hours would prove a great plenty. How we do ramble on! Yet is it not a little fun to stop a moment and conjecture about folks on a distant world? Perhaps they could never be—perhaps Saturn may never mature into a habitable globe—but then, who knows?
The Rings of Saturn
John H. Thayer in his interesting article on Saturn in Popular Astronomy, March, 1919, says: "If you want to see a picture painted as only the hand of God can paint it, go with me to Saturn." He then beautifully describes the scene of the wonderful band of silvery light which arches the sky near the equator, and the bewildering panorama of many moons, full round disks, quarter phases and thin crescents displayed in the Saturnian nights. Not only would the nights be startling to an earth-being; during the daytime their tiny sun would skim across the sky at the rate of about the distance of the diameter of the moon in every minute, and then after the sun literally dropped below the horizon, the stars and crescents and disks and quarters of moons would shoot across equally fast.
Suppose all the inhabitants of the solar system were forced to exist in a medium like the ocean, for instance, to know nothing of such celestial scenes; perhaps the unfortunate inhabitants of Venus can see no more clearly through that dense atmosphere which surrounds their globe.
"One might think that the atmosphere was made transparent with this design, to give man in the heavenly bodies, the perpetual presence of the sublime. If the stars should appear one night in a thousand years, how would men believe and adore; and preserve for many generations the remembrance of the city of God which had been shown! But every night come out these envoys of beauty, and light the universe with their admonishing smile."
The crowning glory of Saturn, its thin flat ring, is poised above the huge body without in any way touching it. Although this ring appears as a solid piece, it is now known positively that it is made up of swarms of meteors or exceedingly minute satellites, all whirling round and round Saturn in the same plane. It may easily be seen why a brightly swirling mass of these shining moons would seem as one object at such a distance.
Through a large telescope it becomes apparent that Saturn's ring is really composed of three rings lying one inside of the other, the two outer rings, which are about 11,000 and 18,000 miles in width, being separated by a dark, narrow clean-cut space of about 2200 miles.
The third ring is a thin, faint inner ring, so transparent that the planet may be seen shining through it. It is about the same width as the outer ring, 11,000 miles, and its inner edge lies only 6000 miles above the surface of the planet. This inner ring is called the "crape ring" because it has a dusky look. It is believed to be the inner ring thinning off toward the planet. It has been suggested that the crape ring may have originated from collisions of particles in the bright ring, thus reducing their orbits, and that the rings of Saturn are slowly shrinking down upon the planet and will sometimes in the future have entirely disappeared.
The first individual to gain a glimpse of Saturn's rings was _-_figure_152.jpg)
TWELVE PHOTOGRAPHS OF SATURN, MADE WITH A 60-INCH REFLECTING TELESCOPE.
Photographs by the Mount Wilson Observatory. Galileo. To Galileo, whose telescope was not much superior to the field-glass of today, the planet appeared triple with two outer stars touching the middle star "like two servants assisting old Saturn to complete his journey." A few years later when he again turned his telescope upon Saturn, these attendant orbs had disappeared. "It is possible some demon mocked me," he exclaimed, and would look no more.
Some one perhaps has lit on a new vein
Of stars in Heaven:"
—Bailey.
Later the side features reappeared and became larger and larger, until they fitted the globe "like a pair of handles."_-_figure_153.jpg)
This drawing shows the rings of Saturn opened to their fullest extent, as seen on July 7, 1898, by Prof. E. E. Barnard through the 40-inch refractor at the Yerkes Observatory. The drawings of those days look very strange to us now, for some pictured a bar run through the planet or a ball with ears. Fifty years later, in 1656, Huygens, with his 123-foot tubeless telescope, solved the mystery and proved the existence of a thin, disconnected ring, which was as astounding a phenomenon as the ears or bars or handles.
Proof by direct observation that the ring was neither liquid nor solid but a multitude of very small bodies journeying close together, was made by Professor Keeler when he applied the spectroscope to determine the velocity at which the rings rotate. It was then discovered that the inner parts revolved more rapidly than the outer parts and the only way in which such a phenomenon can be explained is to accept the hypothesis that the rings are composed of separate independent bodies.
Every 15 years the plane of the ring passes through the plane of the earth and hence it is seen edgewise to the earth. It then almost disappears, being so thin as to be seen only in the larger telescopes._-_figure_154.jpg)
The Earth might "roll upon this ring like a ball upon a road." (Aspects of Saturn's Rings.) From Comstock's "Textbook on Astronomy," by permission of publishers, D. Appleton & Co. Seen edgewise through the 40-inch Yerkes telescope, it is scarcely more than a streak of light "like a pair of illuminated needles piercing the ball on opposite sides." This is because all of these tiny moons which fly about Saturn are moving in the same plane. We obtained this edgewise view in 1907; in 1915 the ring was opened at its widest extent while in 1921 it was again almost invisible.
The reason that this ring may be observed at so many angles is because it is inclined about 27 degrees to the plane of the planet's orbit and about 28 degrees to the plane of the ecliptic. In the course of the earth's journey and Saturn's journey around the sun, we sometimes look up at this ring and sometimes down upon it, but when the earth lies exactly in the same plane, we look only on the edge which is so thin that it becomes almost invisible. The thickness of the ring is, indeed, scarcely anything at all in comparison to its width for, although the distance from one side to the other of the entire ring is about 172,000 miles, its edge is estimated as only about 62 miles.
When the rings are open, the dark shadow of Saturn's planet may be seen against the light of these rings.
This shadow proves that the dull, yellowish glow on the planet is reflected sunlight, and that the planet does not shine with its own light, as a star.
The Moons of Saturn
Besides all the tiny moonlets in the beautiful ring, ten large moons whirl about the planet Saturn. These give Saturn a system with a radius of 8 million miles, which is quite extensive compared to the earth and moon system which has a radius of 240,000 miles.
The moons of Saturn range in size from about 200 miles to nearly 300 miles in diameter but being so far away only Titan, the largest, can be seen except in a large telescope. These satellites were given the names of the brothers and sisters of the God of Time and are called Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Japetus, Phœbe and Themis.
Titan, the largest satellite, is 771,000 miles distant from the planet. The nearest one is only 117,000 miles away but there are also three others which are closer to the planet than our moon is to us. Phœbe, the most distant one, is almost 8,000,000 miles away and takes nearly 18 months to make a revolution. It appears as a full moon only once in a year and a half—quite a contrast to Mars' little Phobos who goes through his phases one and a half times every night! Phœbe seems to be possessed with a streak of contrariness for she moves in her orbit around Saturn in the opposite direction from all of the other moons.
Japetus, the second largest satellite, has the interesting peculiarity of appearing three or four times as bright when on the western side of Saturn as when on the eastern side of it. This is explained by the supposition that one of its sides has a greater reflecting power than the other and, like our moon, always has the same side toward its planet. We would, therefore, see one side of it when east of Saturn and the other side of it when west of it.
Themis, the tenth moon, was first recognized by W. H. Pickering in 1905 but it is only recently that its discovery was fully confirmed. Professor Pickering also discovered the ninth moon of Saturn.