[Illustration: _Eclipse of the Sun. Frontispiece._]
THE STARRY SKIES:
OR,
FIRST LESSONS ON THE SUN, MOON
AND STARS.
BY
AGNES GIBERNE,
AUTHOR OF “AMONG THE STARS,” “SUN, MOON, AND STARS,”
ETC.
[Illustration]
_AMERICAN TRACT SOCIETY_,
10 EAST 23D STREET, NEW YORK.
COPYRIGHT, 1894,
AMERICAN TRACT SOCIETY.
CONTENTS.
CHAPTER I.
This Earth of Ours PAGE 5
CHAPTER II.
Why Men Do Not Fall Off 16
CHAPTER III.
By Day and by Night 27
CHAPTER IV.
How the World Spins 38
CHAPTER V.
The Moon by Night 49
CHAPTER VI.
The Moon’s Changes 61
CHAPTER VII.
The Moon through a Telescope 72
CHAPTER VIII.
The Sun by Day 82
CHAPTER IX.
Storms on the Sun 90
CHAPTER X.
How the World Journeys 102
CHAPTER XI.
Other Worlds 111
CHAPTER XII.
What is Meant by an Eclipse 124
CHAPTER XIII.
Mercury and Venus 136
CHAPTER XIV.
The Planet Mars 147
CHAPTER XV.
The Planet Jupiter 158
CHAPTER XVI.
Saturn, Uranus, and Neptune 166
CHAPTER XVII.
Long-Tailed Comets 175
CHAPTER XVIII.
Little Meteors 184
CHAPTER XIX.
The Sun’s Kingdom 191
CHAPTER XX.
A Starry Universe 200
CHAPTER XXI.
Star-Groups 209
CHAPTER XXII.
Giant-Suns and Clusters 217
CHAPTER XXIII.
How to Study the Sky 226
THE STARRY SKIES.
CHAPTER I.
THIS EARTH OF OURS.
Once upon a time--thus runs a certain tale--there was a man who wanted
to see what could be found at the other end of the world.
So he left his home behind him, and started off to explore. He had
a toilsome journey. He wandered over wide plains; he climbed steep
mountains; he forded dangerous rivers; he crossed stormy seas. Through
weeks and months, and even years, he kept straight on, steadily on,
patiently on, never turning to right or to left. And at last, what do
you think he found?
Was it a world of giants? Or a land of fairies? Or a dark ocean,
without any further shore? Or a vast range of hills, reaching skyward?
Or a profound depth, going downward?
He certainly must have found _something_, because he came to the end of
his journey and travelled no more. He had no need to travel any more.
His task was done: the puzzle was found out; and he had arrived at
“the other end of the world.”
Only it was no “end” at all, but just the very same spot from which he
had started. For he had actually found his way back to his own old home
again.
Don’t you think he must have been rather astonished? It was not at all
what he had expected.
Suppose that a spider, living in the middle of a very big plain, were
to make up his mind to walk to the outside edge of that plain, and see
what might chance to be there. And suppose that, having climbed little
hillocks, and crossed little brooks, trying always to keep steadily in
the same forward direction, he were to find himself all at once back on
the very same spot from which he had first set forth!
He would no doubt be a good deal surprised; and if he had sense to
think the matter over he would see plainly that he had _not_ managed,
after all, to keep going straight forward, but that he must somehow
have turned round without knowing it and gone back to his starting
point.
The man in the story made no such mistake, however. He did not turn
round. He went always on, and on, in exactly the same direction. Yet
in the end he found himself at home! There is the curious part of the
matter.
If the world were a flat plain, like the top of a large round table,
the man could not have done this. It would be out of the question.
He might have turned round and walked back; he could not have walked
steadily onward and onward, farther and farther away from his home,
only to find himself suddenly there again. The thing would be
impossible.
Whether any living man ever took such a journey round the world is more
than doubtful. But I can assure you of this: that if any man ever _did_
take such a journey it would end just as that man’s journey is said to
have ended. By keeping straight forward, always in one direction, and
by going on long enough, he would in time get back to his own house
again.
How could he? That is the question. If a spider were to walk on for
ever, straight across a flat plain, he would never get back to his
starting-point.
But the world on which we live is not a flat plain. For a long while
men believed that it was; and they made a mistake.
Let us think again of a spider--one of those tiny red spiders often
found in a garden--and let us suppose this wee red spider to be
standing on a huge round globe, as large as a house. Suppose that the
spider, having very short sight, fancied himself to be on a flat table
and resolved to take a walk to the further end, to see what he might
find there.
You and I, looking on, would know there was no _end_ to the globe: but
the spider could not guess this. He would walk on and on, in a straight
line, believing himself always to be on a flat surface. And if he
contrived to keep a perfectly straight line all round the globe--not
an easy thing to do--then, whichever direction he began to go in, the
end would be the same: if he kept on long enough he would go round the
whole huge ball, and would arrive again at the spot where first he had
stood.
If he did _not_ manage to keep quite a direct line, but zigzagged a
little to right or left, he would not reach the same _spot_; though
even then he would get back to the same _side_ of the globe as before.
He would find no “end” to it, because a globe, properly speaking, has
no “ends.”
And this Earth, on which we live, is not flat, like a board or table,
but round, like a globe or orange. It is really very like an orange;
for an orange is not a perfect globe, but is a little flattened on its
sides, or, as we commonly say, “at the ends.” Our Earth also is rather
flat in shape at the north and south poles. A round globe, like an
orange, or like the Earth, has really no “ends” at all: though we often
use the word when speaking of the two poles.
If you were to take such a journey, starting from your home, and
keeping a perfectly straight line onwards always in one direction, you
too would in time come back to the spot from which you started.
But a journey of this kind would be very hard to manage: far more so
than it sounds. Every little hillock, every little streamlet, every
house and every tree, to say nothing of rivers and towns, mountains and
oceans, would turn you out of your path. By the time you got round the
world, although you would return to the same _side_ of the globe from
which you first set out, you might be a long way off from the exact
spot.
In case you do not know where the two “poles” are, you should ask some
one to show you on a school globe. The north pole and the south pole
are both very cold parts of our Earth. Ice and snow are there all the
year round.
Half way between the north and the south poles is the equator--a line
drawn exactly round the whole Earth: and all round the Earth, on or
near the equator, are the very hottest countries. About half way
between the north pole and the equator, and between the south pole and
the equator, are the “temperate” parts of the Earth--not so very cold,
or so very hot.
If a man is travelling from near the north pole towards the equator,
or from near the south pole towards the equator, he gets into warmer
and warmer places.
But if he is travelling from the equator towards the north pole, or
from the equator towards the south pole, he gets into colder and colder
places.
The right name for a globe-shaped body, like an orange or like the
Earth, is a “sphere.” Neither an orange nor the Earth is a _perfect_
sphere, because both have flattened ends; still, the ends are only a
little flattened, and we always speak of the Earth as a “sphere.”
A “hemisphere” means a “half-sphere.” If our whole Earth were cut into
two equal-sized pieces each of those pieces would be a “hemisphere.”
We always think of the equator as dividing our Earth into two halves.
The half towards the north is called “the northern hemisphere;” and the
half towards the south is called “the southern hemisphere.”
Since our Earth is said to be a round globe, like a ball, why do we
not see over the edge? A fly, standing on an orange, would have, it
is true, a rounded surface just under his feet; but he could take a
good view downward over the edge. It would _look_ like an edge to him,
though there is no edge really to a ball.
If our world were as small as an orange, and we by comparison were each
as large as a fly, then we should be able to do the same.
But the Earth is huge in size: and we are very tiny--yes, exceedingly
tiny, side by side with the great Earth! And the surface on which we
stand curves away so very gently, so very gradually, that it looks like
a flat surface to us--just as the large globe would have seemed flat to
the wee red spider, only very much more so. For the difference in size
between the Earth and a man is far greater than the difference between
the globe and the spider.
You may get some idea of how things are, by standing on the sea-shore,
and gazing out to sea. Far away the sky and earth seem to meet in a
long line, which we call “the horizon.” That line is always around you,
on all sides, wherever you are, though often you cannot see it, because
of hills or buildings or trees coming between.
Beyond that line the rounded surface of the Earth _drops_ away, so that
you can see it no more. It is, in fact, what looked like an _edge_,
to the fly standing on the orange. To us it looks much more as if the
ground slanted upwards to meet the sky. But there is no real upward
slant. After a certain number of miles, the surface of the ground or
the ocean dips downward, out of sight, and all else beyond that line
is out of sight also.
Put your eyes close down upon a large schoolroom globe. You will see at
once how the solid ball hides from you part of the room. You can see
the ceiling, and perhaps the window and the fireplace, but beyond the
globe all is hidden. Your _horizon_, as you stand thus, is just where
you seem to see a sort of edge to the globe, beyond which its rounded
surface dips away, out of view.
Looking upward into the sky we are able to see enormous
distances--hundreds of miles, thousands of miles, millions of miles,
billions of miles away! Light travels to earth from far, far distant
stars: and we can perceive those feeble gleams because nothing comes
between to hide them.
On the Earth it is very different. Here we can commonly see only a few
miles off. Not because our eyes are not strong enough: but because the
Earth’s rounded surface soon dips away, and all beyond that dip is cut
off from us by the solid body of the Earth.
On a flat plain, or close to the surface of the sea, our view is very
narrow. If we climb a hill we get a wider landscape, because we can
see farther over the “dip,” and from a mountain-top the view is very
greatly increased.
[Illustration: _Sunset._]
Still, no matter how high we go, the Earth’s surface always stretches
away to north and south, to east and west. It always _seems_ to rise
and meet the sky, making our horizon-line.
If we could get very, very far off indeed, into the sky, we should
then see our Earth floating, like an enormous ball--a huge round solid
globe. But this we are never able to do. We know our Earth to be a
round ball: but we cannot stand apart and see her to be such.
Did you ever notice a ship “hull-down” on the horizon?--that is, with
its masts standing up above the horizon, and its body hidden?
This again was caused by the shape of the earth: the hull of the ship
having dipped down below the horizon, while the masts still stood up
within sight.
When we see the Sun in the sky, he is always a round body. But when he
sinks at night below the horizon part of the round surface is hidden
first, and then the whole. Hidden in the same way: by the Earth’s
rounded surface coming between him and our eyes.
At the moment when the Sun is all but gone, only one glimmer being
visible, you might say of him too, as of the ship, that he is
“hull-down.”
QUESTIONS.
1. What is a Sphere?
A body in the shape of a rounded ball or globe.
2. What shape is our Earth?
The Earth is a sphere in shape: but not a perfect sphere, because
flattened at the north and south poles.
3. What is a hemisphere?
A hemisphere is a half-sphere.
4. Describe the two hemispheres of the Earth, commonly so called?
The northern hemisphere is the whole of the Earth north of the equator;
and the southern hemisphere is the whole of the Earth south of the
equator.
5. What is the Equator?
A line supposed to be drawn round the whole earth, exactly half-way
between the north and south poles.
6. What is the horizon?
The horizon is that line in the distance where the sky and earth seem
to meet.
7. What hides all below the horizon?
The solid body of our Earth.
8. How far can a man see on the Earth?
A few miles, usually. On a hill he has a much wider view.
9. How far can a man see in the sky?
He can see stars millions and billions of miles away.
10. What is meant by a ship “hull-down?”
A ship “hull-down” is partly above and partly below the horizon.
11. What becomes of the Sun when he sets?
He goes down below the horizon.
12. Is the Sun then too far off for us to see him?
No: he is only hidden from us after sunset by the solid body of the
Earth coming between him and our eyes.
13. Does the Earth’s surface really rise to meet the sky?
No: it really drops away, so that beyond a certain line we can no
longer see it.