THE PLANET MARS.
Next outside the pathway of Venus comes the pathway of another planet,
named EARTH--this same globe on which we live. From it, as from a
little boat on the great ocean, we look out upon other floating worlds,
and upon the countless stars.
We can see the worlds and stars, but we cannot get to them. All of us
are prisoners upon this little Earth-boat, during our earthly lives.
As a Planet our Earth is one of the smaller worlds. She is nearly 8,000
miles through, and about 25,000 miles round. She has a north pole and a
south pole, and an equator. She has many continents and oceans, part of
her surface being Land, and a larger part being Water.
The Earth spins on her axis once in twenty-four hours; and she travels
round the Sun once in twelve months, going at a rate of about nineteen
miles each second.
This is not so fast as Venus, and not nearly so fast as Mercury; yet it
is seventy times faster than the speed of a cannon-ball.
Think of our whole big Earth, with all of us on board, rushing wildly
through the sky more than seventy times as fast as a cannon-ball rushes
through the air. Only it is not “wildly;” the movements of the worlds,
though very rapid, are calm and quiet.
Our Earth, like Mercury, goes sometimes a little faster and sometimes a
little more slowly. When nearer to the Sun she travels faster, and when
farther off from him she travels more slowly. But the differences in
her speed are much less than in Mercury’s, because her pathway is not
so oval in shape, and so she is always more nearly at one distance from
the Sun.
Outside Earth’s pathway is that of MARS, the last of the Four Lesser
Worlds.
His untwinkling red gleam is easily seen. Not always in the east or
west, like that of Mercury and Venus; but, like all the outer planets,
in different parts of the sky at different times.
Mars is much smaller than our Earth. He is only some 4,000 miles
straight through. A big knitting-needle which might run just through
him would have to be twice as long as one for the Moon, but only half
as long as one for the Earth.
It takes Mars about twenty-four hours and a half to spin once on his
axis; so days and nights are much the same in length there as with us.
His axis, too, seems to lean over very much as our Earth’s axis does,
and that would give Mars seasons a good deal like ours.
Only, as the year of Mars is almost as long as two Earthly years, his
seasons would last much longer. Spring and summer, autumn and winter,
would be each about five or six Earthly months in length.
The distance of Mars from the Sun is about 140 millions of miles.
So Venus is somewhere about twice as far off from the Sun as Mercury.
The Earth is about three times as far as Mercury. Mars is more than
four times as far as Mercury.
Mars is a very interesting little world. Not so brilliant or lovely as
Venus, but really more easy for us to study and examine. Venus seems to
be so covered with masses of white clouds that we can see very little
of the planet itself; but Mars is not covered with clouds.
Mars never comes so near to us as Venus does. Only, unfortunately,
Venus at her nearest cannot be seen at all, because her bright side
is turned away from the Earth and towards the Sun. While Mars at his
nearest, being _outside_ the Earth, can be looked upon nicely, for the
Sun then shines full upon that side of Mars which is towards us.
When we talk of “studying and examining” a world which never by any
chance comes closer than 35 millions of miles away, we have to be
careful. It does not do to guess at things, or to be in a hurry to
settle what cannot be truly known.
Even with the Moon we found that the biggest of telescopes cannot make
her look very much less than one hundred miles away. But Mars is a
great deal farther off than the Moon.
Just think of the difference! The 240 _thousands_ of Moon-distance are
changed into 35 _millions_ of miles for the distance of Mars. And the
most powerful telescope cannot bring down those 35 millions of miles to
less than about 35 thousands of miles.
So when people talk about Mars, and about what may be seen on Mars,
remember this--that at the very best _we can only see Mars as we should
see a world 35 thousands of miles away_!
On the Earth even a hundred miles seems a long distance. From the
top of a mountain one can see to a hundred miles no doubt, in clear
weather; but very little can be made out at such a distance. Yet a
hundred miles would be only a small piece of one country. It takes ten
hundreds to make a thousand, and a thousand miles off seems to us very
far indeed.
Nobody on the Earth can ever be farther from us than about 8,000 or
about 12,006 miles off, that is, through the middle of the Earth 8,000
miles, or reckoning round the outside rather over 12,000. You know how
distant Australia seems from us.
But Mars at his nearest, and looked at through the largest of
telescopes, is still only seen as a world _three times farther away_
than the very farthest off country upon this whole Earth from you or me.
Of course it is very wonderful that a planet thirty-five millions of
miles away can be actually seen through a telescope as if it were only
thirty-five thousands of miles away. Still, at the best, thirty-five
thousands of miles is a pretty good distance.
Although we cannot find out half or a quarter of what we want to know
about Mars, still we do know a good deal. The big telescopes tell us
much, and another instrument, called a “spectroscope,” tells us yet
more. But in this small book I cannot even try to explain to you what a
“spectroscope” is.[1]
[1] See “Sun, Moon, and Stars,” page 307.
We know that Mars has some sort of air, perhaps rather like our Earth
air, only more thin. We know that water floats in that air, as water
floats unseen in our air.
As for climates, one might expect Mars to be terribly cold at such a
distance from the Sun. He cannot have half the quantity of light or
heat that we have. Yet, somehow, there seem to be signs that Mars is
not a very much colder world than our Earth is.
At the north pole and the south pole of Mars tiny white caps, or
patches, are seen; and these are most likely made of ice and snow. We
on the Earth have always ice and snow at our two poles; and people on
another world, a long way off, might perhaps see our polar ice and snow
as white caps, or patches.
Sometimes clouds are seen to flit across Mars, white clouds, like the
white clouds which cover Venus. This only means that they are white
outside, on the _upper_ surface, where the Sun shines. They may be gray
below, like so many of our gray Earth clouds, though we also often see
clouds white and shining in sunlight. And when a man gets up a high
mountain above the clouds, and looks down upon them, he sees their
upper surface, white as snow and beautifully bright.
Mars commonly looks red, when seen without a telescope. If seen through
a telescope, greenish and purplish patches are found. It is very likely
that the one color shows land and the other water. Since Mars has
water-vapor in the air, and probably snow and ice at the poles, he is
pretty sure to have oceans also. But the continents and oceans of Mars
are differently shaped from ours. There seems to be more of land and
less of sea.
[Illustration: _Mars. August 22 and 29, 1892._]
Thus in a good many ways Mars is not so very unlike our Earth, his
next-door neighbor. Day and night seem to be much the same in both
worlds, also summer and winter. We think, too, that we find there
air and water, snow and ice, lands and seas, changes of weather and
differences of climate, more or less like those of the Earth.
But if you ask me whether animals and men and women and children live
on Mars, I can only say that _nobody knows_. It may not be impossible,
so far as we are able to judge. We feel pretty sure that no living
creatures such as we ever see on the Earth could exist on the Moon or
the Sun. And with Mercury, if not also with Venus, we are hardly less
sure, when we think of the intense glare and awful heat in which those
two worlds travel.
With Mars there is some difference. Knowing the little we do know, it
certainly seems a thing by no means out of the question that living
creatures _might_ find a home on Mars--creatures not utterly unlike
those upon the Earth. But we cannot for a moment say that they do.
One difference between Mars and the Earth which would make life there
very unlike life on the Earth is its small size.
On Mars, as on the Earth, there is the “pull” of attraction. “Downward”
all round the planet is towards the centre of Mars, and “upward” all
round is towards the sky of Mars; and everything in Mars is heavy
towards the centre of the planet.
But the _pull_ there is much less than here, because Mars is so small;
and the less pull means less weight. A lump of iron which weighs ten
pounds on the Earth would weigh less than five pounds on Mars. If a man
went to Mars he would be as light there as a boy on the Earth; and if a
boy went there he would weigh as little as a baby on the Earth.
The two moons which travel with Mars are very tiny, perhaps only about
eight or ten miles through.
Between the planet Mars and the planet Jupiter lies an enormous gap of
millions of miles empty of all large worlds, even of worlds as big as
our Moon.
Somewhere about the middle of that vast gap, about half-way between
Mars and Jupiter, is the belt of PLANETOIDS.
Less than four hundred of them are as yet actually known to us; but
perhaps thousands of them may be there. Each of these tiny planets has
its own pathway round the Sun, and their pathways do not keep nearly to
the level of the Earth’s pathway, like those of the bigger worlds.
Vesta, the largest of them all, is perhaps over three hundred miles
through, and three others come rather near Vesta in size. The greater
number are under one hundred miles through; some being mere balls,
about the size of Mars’ moons.
QUESTIONS.
1. Which is the next planet outside Venus?
The Earth on which we live.
2. How far is the Earth from the Sun?
About 92 millions of miles.
3. How fast does our Earth travel?
About 19 miles each second.
4. How long is the Earth’s year?
About 365 days, or 12 months.
5. Which is the next planet outside the Earth?
Mars.
6. What is the diameter of Mars?
About 4,000 miles, or half that of our Earth.
7. How far is Mars from the Sun?
About 140 millions of miles.
8. How long is Mars’ year?
Nearly twice as long as our year.
9. Does Mars spin on his axis?
He is believed to do so, in twenty-four hours and a half.
10. How near does Mars come to us?
Never closer than 35 millions of miles off.
11. But how much nearer does the most powerful telescope seem to bring
Mars?
Perhaps to about 35 thousands of miles off.
12. Are air and water found on Mars?
Some kind of air, and water also, and ice and snow.
13. Are there oceans on Mars?
There are patches of color which may be continents and oceans.
14. Where are ice and snow perhaps seen on Mars?
White caps are seen at the two poles.
15. Is Mars inhabited?
Nobody can tell. It does not seem to be quite impossible, so far as we
understand what Mars is like.
16. Which planet comes next after Mars?
Hundreds of Planetoids come next.
17. Are they close to Mars?
No; there is a great space between Mars’ pathway and Jupiter’s pathway;
and the Ring of Planetoids lies somewhere about the middle of that
great space.
18. What is the name of the biggest Planetoid?
Vesta.