LITTLE METEORS.
Meteors are the very smallest bodies of which we know, that float and
rush about in the sky.
Besides being the smallest they are also the most abundant. Their
numbers are not only past counting, but past our power to imagine.
We cannot see them as they speed hither and thither through the skies,
travelling either alone or in tens of millions.
Each one indeed gives forth its tiny light, borrowed from the Sun. But
those dim gleams are far too weak to reach us here on Earth. The only
time when they can be seen by us is when they come by accident into our
air.
Then indeed we do see them--not by the gentle shining which they catch
from the Sun, but by one brilliant flash of light as they are destroyed.
It is the rush through our thick air which destroys the meteors. The
air always tries to hold back anything moving fast through it.
A meteor far away in the sky is a hard and cold little body--very cold
indeed, out in the terrible cold of Space. It has no light of its own
to give forth.
And in the sky a meteor goes very fast, rushing round the Sun. When it
first gets into our air it keeps up that great speed. The air tries to
hold it back; and the rubbing of the air against it heats the outside
of the little meteor so intensely that it glows with bright light.
It becomes in fact “white-hot.” The outside melts and pours away in a
stream of shining dust, which to us looks like a tail of light. The
dust soon cools, and drops gently down upon the ground.
Before the meteor has rushed twenty or thirty miles it is generally
done for. All of it has gone off in bright dust, and nothing is left of
the tiny heavenly body except that dust.
This is what you see when you look at a “shooting star” after dark.
Of course you have seen shooting stars very often. If not, you should
begin to look out for them as soon as possible.
A shooting star is no star at all, really. It is only a little meteor,
or meteorite, which has travelled for ages in the skies, and which has
at last happened to come too near to our Earth. The strong pull of the
Earth’s attraction has dragged it into the air, and so it has perished.
Hundreds and thousands of meteors are ever dropping earthward. If
it were not for our soft protecting air we should be under a regular
cannonade from the sky; but happily most of the cannon-balls are used
up long before they can reach the ground.
On the Moon, where there is no protecting air, one would have to
undergo a fearful battering.
Now and again a meteor is large enough not to be _all_ destroyed in its
rush downwards. A good part is melted, and runs away as a little tail
of brightness, but both speed and heat grow less before the whole is
gone.
So then part falls to the ground as a solid stone, or as a lump of
iron and other metals. We call the fallen lump an “aerolite” or a
“meteorite,” or a “meteoric stone.” But it is commonly just a meteor
which has come to us out of the sky.
Some very large aerolites have been known to burst in the air with a
great noise, and to scatter hot stones over the land below. This sort
of thing happens very seldom.
There are wonderful Rings of Meteors journeying round the Sun--enormous
companies of millions upon millions of little dark cold bodies, lighted
up by the Sun’s rays.
Every August and November our Earth in her journeying touches one such
Ring. In those months a great many more “shooting stars” may be seen
in the sky than at other times of the year. So, when you want to see
shooting stars, remember that the best times are August and November.
If then you watch the sky steadily after dark for half an hour you will
hardly fail to see at least two or three.
About once in every thirty-three years our Earth plunges into the very
thick of one of these Meteor-Rings. And then indeed we may have a
splendid sight!
Tens of thousands of meteors can be seen flashing through the air, each
with its little train of light behind. Fast as they appear and vanish
tens of thousands more follow; and for hours this goes on.
Yet even then the number of meteors which can be seen is as nothing
compared with the vast hosts which cannot be seen because they do not
come into our air.
Sometimes comets and meteor-rings are found together, journeying in
company. That is to say, the comet journeys with the meteors, in the
same ring or pathway round the Sun. This really seems to show that the
one may belong to the other.
I have told you already that comets, or at least comets’ heads, are
believed to be made partly of little meteors. If things are so, one
would not be surprised to find a very close tie between comets and
rings of meteors.
You will remember Biela’s Comet, spoken of in the last chapter, which
some people think has actually broken up into separate meteors.
It is thought very likely that the wonderful Rings of Saturn are
entirely made of meteors. Not of bright dying meteors, as we see them
in our air, but of countless millions of tiny hard bodies, all whirling
together round and round the huge planet, and giving forth such light
as they can borrow from the Sun.
Sometimes on the Earth a faint light is seen, of a sugar-loaf shape, in
the eastern sky, before dawn, or in the western sky after sunset. It is
called the Zodiacal Light, and it plainly has to do with the Sun. It is
always seen very near to the Sun, never anywhere else.
We know little about this curious light, but it too _may_ be caused by
the shining of enormous numbers of meteors, all whirling round the Sun.
No doubt countless multitudes are ever dropping down upon his fiery
surface.
Each little meteor that journeys round the Sun shined, like the worlds,
on one side only--that side which is towards the Sun.
QUESTIONS.
1. What are Meteors?
The smallest heavenly bodies known to us.
2. How many meteors are there?
Immense multitudes in the sky, beyond our power even to imagine.
3. How do meteors shine when journeying in the sky?
They shine by borrowed sunlight.
4. Does a meteor shine all round?
No; only on that side which is towards the Sun.
5. Do we see meteors by means of that borrowed sunlight?
No; we only see them when they rush into our air.
6. What makes them visible to us then?
They are so much heated by the rubbing of the air as to shine brightly
for a moment with their own light.
7. What becomes of such meteors?
The outside is melted and streams behind as shining dust.
8. Does any part of them reach the ground?
Generally they are destroyed in their rush through the air, and only
the dust drops downwards.
9. Are they always quite destroyed?
Sometimes a part escapes, if the meteor is rather large, and then a
solid lump of rock or metal comes to the ground.
10. What is such a lump called?
A Meteorite, or an Aerolite, or a Meteoric Stone.
11. What is it really?
Part of a meteor from the sky.
12. What do we call a meteor seen only by its last flash?
Either a “meteor” or “a shooting star.”
13. When are shooting-stars most common?
In August and November.
14. Why?
Because our Earth then touches meteor rings, and so a great many come
into our air.
15. When does our Earth plunge deep into a meteor-ring?
About once in every thirty-three years.
16. What is seen then?
A most wonderful display of tens of thousands of meteors.