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: 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 5⅛
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."
--_Emerson._
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.
[Figure 152: TWELVE PHOTOGRAPHS OF SATURN, MADE WITH A 60-INCH
REFLECTING TELESCOPE.
Photographs by the Mount Wilson Observatory.]
The first individual to gain a glimpse of Saturn's rings was 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.
"But for these news I know not what they be,
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: 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: 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.
"While Saturn whirls, his steadfast shade
Sleeps on his luminous ring."
--_Tennyson._
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.