Part 4

Betty added a few lines to show that _Andromeda_ was lying on a pile of hay, instead of being chained to that hard rock the Greeks insisted upon.

"What is that fuzzy little star just to her right, about at her hip?" asked Paul.

"I'm glad you noticed that," said Uncle Henry. "The astronomers who lived ever so long ago, long before the birth of Christ Jesus, noticed that it looked 'fuzzy,' just as you have, and called it 'the little cloud.' It is now called 'The Great Nebula in _Andromeda_.' If you looked at it through a telescope you would see that it is not one star, but a great many. Some of them, as astronomers who live now tell us, are as large as our sun."

"Ooh, how wonderful!" said Betty softly, and the boys' faces showed that they thought so, too.

"Some night," promised Uncle Henry, "we'll bring up a little telescope and look at 'the little cloud' again. It is a fine sight."

"Now," said Paul after a moment, "please can I find the ram and the little dog?"

"Certainly," said Uncle Henry. "Just as _Canis Major_, the bigger dog, follows _Orion_ and belongs to him, so _Canis Minor_, the littler dog, follows and belongs to the star children, the twins named _Gemini_."

"Ooh!" exclaimed Betty, "just like 'Rags' belongs to Peter and Paul! We'll call the little dog 'Rags' when Paul finds him."

"Fine!" laughed Uncle Henry, "but I warn you that he won't come when you call him as well as the real live 'Rags' answers to his name."

"Where do I start?" inquired Paul, anxious to have his chance to draw.

"At the feet of the twins," directed Uncle Henry. "Draw a line through their feet and extend it away from the feet of _Pollux_, in the direction away from _Taurus_, the bull. (26) At a point about as far away from the foot of _Pollux_ as the height of the twins you will find a bright star, and between it and the foot of _Pollux_ a fainter one. Draw a line to connect them, and you have the little dog's backbone. You can fill in the rest of him any way you like, for those are the only two stars he has in him. I'll tell you one thing, though. The brighter star is at the little dog's tail instead of his head. The opposite was the case with _Orion's_ dog."

The children found the two stars very easily and Paul put down dots of the right size to represent them. Then he drew the outline of the little sky dog, making him an Airedale, as you can see, so that he might be the same as his beloved flesh and blood name-sake "Rags."

"Now that we've found the two dogs, that makes it easy to find _Cancer_ the Crab," said Uncle Henry. "Just draw a line from _Sirius_, in the Big Dog, through the Little Dog, and extend it almost as far again. (27) That's right. Now what do you see?"

The children searched the sky for some time, and Betty finally said, "Sort of a sprawly bunch of six or eight rather faint stars."

"Make little chalk-dots for them, then, Betty, and we'll try our best to make them look like a crab."

This shows how _Cancer_ the crab looked when he was finished on the blackboard, and how he crawls in the sky away from _Canis Major_ and _Gemini_, the twin boys. Perhaps he has learned by experience to leave boys and dogs as far behind as possible.

"Now let's find the ram!" said Paul. "I want to draw him."

"The ram," said Uncle Henry, "is very small, and is made of only three stars. A line drawn from the top corner of _Pegasus'_ box stall, on the side next the pole, going straight down the side, and extended below it one and a half times the height of the stall, will point to the ram. (28) You can also locate _Aries_, the Ram, by drawing a line from the star in the swan's tail, across the stars in _Andromeda's_ hips, and beyond them a little more than the distance from her head to her hips. Don't mistake a little triangle of stars that you will see just below _Andromeda's_ left leg for the three stars of _Aries_. _Aries_ is a triangle, also, but it has _two_ fairly bright stars, while the triangle has only _one_. Do you all see _Aries_, the Ram?"

The children had all found it after a few moments, as well as the triangle under _Andromeda's_ feet. When Paul had made the chalk dots and lines for _Aries'_ skeleton, Uncle Henry drew the outline around them and the ram looked like this. You will see that in order to show _Aries_ right side up, the blackboard had to be turned so that _Andromeda_ was upside down.

"While we are in the neighborhood of _Pegasus_ and _Andromeda_ and _Aries_ the Ram we may as well find the two fishes. One of them, called the _Northern Fish_, lies just about halfway between _Andromeda's_ body and _Aries_--and the other, called the _Western Fish_, lies just back of _Pegasus'_ box stall, quite close to the water jar of _Aquarius_. (29)

"The two fishes are tied together by their tails. The cord or ribbon runs eastward from the tail of the _Western Fish_, running about parallel to the side of _Pegasus'_ stall, and then makes a sharp angle, coming back toward _Andromeda_, where it is fastened to the _Northern Fish's_ tail."

When _Pisces_, or "The Fishes" were found and drawn with chalk they were in this relation to _Pegasus_, _Andromeda_, _Aries_, and _Aquarius'_ Jar.

"While I think of it," said Uncle Henry, "I want to tell you that sometimes you may find a very bright star in a constellation where it doesn't seem to belong. If you watch it for a few nights you will see that it moves. It isn't a star at all, but a _planet_ or "wanderer." Sometime I'll show you how to know all the planets by sight and name. You will never see them except in the zodiac constellations, so they need not confuse you. And now I think all of us had better go downstairs and get warm before we go to bed. Besides, we want to leave a little to do to-morrow night, and there are only two constellations left now."

"Only two?" cried the children in disappointment.

"Only two that we can see well," assured Uncle Henry.

"Well," said Peter, "I guess we'd better have the Society adjourn. I move we adjourn."

"Second the motion," said Paul, with true parliamentary solemnity.

"Carried," murmured Betty, who was beginning to get sleepy in spite of herself.

THIRD WINTER EVENING

THE SKY CLOUDED OVER, BUT PETER FOUND THE STAR PEOPLE HIDING IN THE ALMANAC--PAUL FOUND HIS HEAD WAS THE WORLD--AND THE "SOCIETY" FOUND OUT ABOUT THE SWASTIKA AND THE ZODIAC, AND HOW YOU TELL WHEN A DIPPER IS A PLOUGH AND WHEN IT'S A WAGON

Next evening Peter and Paul carried the blackboard to the roof after supper, but soon returned in disappointment. The sky had all clouded over! The evening's session of the "Society of Star-Gazers" was spoiled. Its members stood in a circle about Uncle Henry and looked hopefully at him. Never yet had he failed to make good in an emergency.

"Well, it can't be helped," said Uncle Henry cheerfully. "We'll just have to bring Starland down here into our playroom for this evening. Suppose you get me--let's see--about a dozen sheets of paper from a big scratch pad, some of Betty's colored crayons--they had better be the dark-colored ones--and a good-sized sheet of stiff cardboard or Bristol board. Yes, and some pins and an Almanac. Betty'll get the colored pencils, Paul the cardboard, and Peter the sheets of paper and the pins. I'll borrow the Almanac from Katy. She has one in the kitchen."

The children scattered for the materials and Uncle Henry took the shade off the electric lamp that stood on the playroom table.

When everybody was back in the playroom with the things needed the Society gathered around Uncle Henry and asked,

"Where do we go from here, Uncle Hen?"

"Out into Starland," said Uncle Henry, spreading out his arms wide. "This room is the universe. This lamp with the shade off is the sun. Imagine that the pictures on the walls are groups of stars, the constellations, the star-people we have been finding in the sky right along. Imagine that there are pictures on the ceiling, too, and on the floor. Lots of them, all over the six sides of this square room.

"Now Paul, you have a nice round head and have just had a hair-cut. Your head can be the earth. Just walk around the table once or twice until we get used to thinking about your head as the world. It seems rather small at first. That's right. Now you're going around the sun the way the earth does, from right to left, just opposite to the way the clock-hands go. You go once around the sun every year.

"The earth of course spins on its axis, too, just like a top, while it is circling round the sun. It turns round completely every twenty-four hours, from West to East. Paul, see if you can spin like a top while you are going round the lamp. Spin from right to left, just opposite to the way the clock-hands go."

Paul did his best to spin and walk at the same time, and Uncle Henry showed Peter and Betty that the side of Paul's head that was toward the lamp was always bright, while the other side was always in shadow. As Paul turned on his axis from right to left his face became lighted, then the right side of his head, then its back, then the left side, and so on, round and round.

Part of the time Paul was facing a picture on one wall and the next minute his back was toward that picture and he was looking at another picture on the opposite wall, across the lamp.

These two drawings show how Paul faced the two pictures one after the other.

"Now tell me," commanded Uncle Henry, "which picture you see the plainest--is it the one you see when your back is to the lamp--or is it the one you see when you face the lamp, and look across it toward the picture on the wall beyond?"

"The lamp is so bright without a shade that it blinds me when I try to see the picture beyond it," said Paul.

"Oh, I see! I see!" said Betty, beginning to hop up and down. "Can I tell, Uncle Henry?"

"Surely," laughed Uncle Henry, "what do you see?"

"When Paul faces the picture with his back to the lamp," said Betty, "it's night on his face, and day on the back of his head! Is that right?"

"Yes, go on," encouraged Uncle Henry.

"And so he can see that picture better, 'cause the lamplight isn't in his eyes. But when he faces the lamp and looks across it, then it's day in his face, and night on the back of his head, and he can't see the picture beyond the lamp very well, 'cause the sun-lamp shines in his eyes."

"So that's why we can only see the stars at night!" said Peter.

"Yes, that's why the moon and the stars come out only when it gets dark," said Uncle Henry. "You see the earth turns round and carries us to its dark side, the side that is away from the sun. We say 'The sun has set.' Then when the sun glare is gone from our eyes we can see the sky-pictures, just as Paul sees one picture better with his back to the lamp than he does the other when he has to look through the lamp-light toward it."

"And the stars are in the sky all day long, whether we see them or not?" asked Paul.

"Certainly," said Uncle Henry. "If you could look up at the sky from the bottom of a very deep well, or a tall chimney, so that the sun-light was kept out of your eyes, you could see the stars shining in the daytime. There is a long deep tunnel in the great pyramid of Egypt that goes up and out from the centre of its base toward its north side at just the right angle so that the ancient Egyptians could always see the pole star through it--no matter whether it was night or daytime. You see the pole star never rises or sets, because it is always right over the end of the axis that the earth spins on."

This picture shows how the tunnel in the great pyramid always pointed to the north star because the tunnel is always parallel to the axis the earth spins on.

When the pyramid was built, the star in the tip of the little bear's tail was not the pole star, as it is now. At that time the star that was nearest the pole was one of those in the dragon. Since the pole of the earth goes round in a complete circle among the stars every 25,000 years, the star in _Draco_ will some time be the pole-star again--in, say 20,000 more years!

Peter had picked up the Almanac that Uncle Henry had borrowed from Katy and suddenly cried,

"Oh, Uncle Henry, the Almanac has a lot of the Star People in it. It calls them 'The Signs of the Zodiac.' What's the Zodiac, Uncle Hen?"

"We are going to find out right away, Pete," said Uncle Henry, "but first we must draw pictures of the twelve star folks that are the Zodiac signs. That means three drawings apiece. Pull up your chairs to the table and we'll draw on the sheets of scratch paper with Betty's colored pencils. Paul, you do the _Virgo_, _Leo_, and _Cancer_ the Crab; Peter will draw _Gemini_ the Twins, _Taurus_ the Bull, and _Aries_ the Ram; Betty will do the Fishes, called _Pisces_ in Latin, _Aquarius_ the Water Carrier, and _Capricornus_ the Goat; while I will draw _Sagittarius_ the Archer, _Scorpio_, and _Libra_ the Balance. All old friends of ours."

"We'll put the Almanac here in the middle of the table where we can all see it while we copy the 'signs,' one on each sheet of paper."

Everybody was very busy indeed for about half an hour. At the end of that time the twelve rough drawings were done and pinned up at equal distances apart around the walls of the playroom, three on each of the four walls. They were arranged around the room in the same order in which Uncle Henry had assigned them. The room then looked like this, though of course you see only three walls in a picture. You must imagine how the fourth wall looked.

"Now Paul, suppose you walk around the table again, spinning on your own axis as you go, and we'll try to find out what the Zodiac is. You notice that the pictures are all pinned on the walls at the same height from the floor, which is just the height of the electric lamp bulb, and just the height of Paul's head too, no matter where he is in his walk around the lamp. The twelve constellations, or signs of the Zodiac are in the real sky also on the same level with the earth and the sun, no matter where the earth is in its journey round the sun. Astronomers say it this way: they say that the earth revolves around the sun 'in the plane of the ecliptic.' That simply means that if the sun was in the centre of an enormous horizontal pane of glass, the earth and all the signs of the Zodiac would also always be touching the pane of glass, which would then represent the 'plane of the ecliptic.' Put an l in 'pane' and you have 'plane.'"

"Is each sign for a month?" asked Peter. "I see there are twelve of them."

"That's correct," said Uncle Henry, "and you want to notice that as Paul walks round the lamp and looks across it at the signs on the wall beyond it, the lamp seems to Paul to move from one picture to the next."

This picture is drawn as if the ceiling of the room was taken off and you could look down on Paul walking around the lamp.

When it is January first, Paul, representing the earth, is in the position marked A, nearest to the picture of _Gemini_ behind him, while the lamp, representing the sun, appears to him to be entering the sign of the Zodiac called _Sagittarius_, directly opposite across the room. Later, on April first, after three months, Paul, or the earth, has traveled a quarter of the way around the sun, has passed the pictures of _Cancer_ and _Leo_ on the wall behind him, and stands nearest _Virgo_ in the position marked B. The lamp has also seemed to move through a quarter circle, has passed through the signs of _Capricornus_ and _Aquarius_, and appears to Paul to be just entering the sign of _Pisces_, or the Fishes. In the same way the earth moves through a sign of the Zodiac every month and the sun, while really motionless, _appears_ to also travel through a sign every month. Of course we cannot see the sign or constellation, where the sun appears to be, at the same time we see the sun, for his brightness makes the stars invisible, but if we _could_ see the constellations by day, the sun would appear to travel from one sign of the Zodiac to the next every month.

Here is a clock of the year which shows the earth at one end of the hand, the sun in the middle, and at the other end of the hand an arrow, which points to the sign of the Zodiac where the sun appears to be, and to the date when it seems to be there to an observer on the earth. Draw the hand with the earth-end in several different positions and you will see that the sun, if viewed from the earth, would appear to be in the sign of the Zodiac exactly opposite.

When the children all understood the way the Zodiac divides the yearly path of the earth into twelve equal parts, Betty said, "I want to know why the geography globe at school always looks just as if it was going to tip over."

Uncle Henry laughed. "If you think the geography globe looks unsteady because its axis of iron rod is on a slant, what will you think about the earth when I tell you that it spins around in just the same slanting position, with only an _imaginary_ line for axis?"

"Does it really?" asked Betty.

"Yes," said Uncle Henry, "and it spins so steadily in that slanting position that the north end of its imaginary axis always points toward the same place, a point very close to the north star, or _Polaris_ as it is called."

"_Polaris_ is named for the North Pole, I suppose," said Peter.

"That's right," Uncle Henry replied. "Let's get some scissors and we'll use our big sheet of cardboard to make a cap for Paul's head that will show you just how the slant of the earth's axis makes it hotter in summer and colder in winter."

"Ooh!" exclaimed Paul, "I always thought it was hot in summer because the earth got nearer to the sun then."

"Lots of people think that, too," said Uncle Henry, "but it isn't so. The earth is really farther from the sun in summer."

Betty ran for the scissors, and Uncle Henry cut out a big circle from the stiff cardboard. Then he cut out an opening in the centre of it that fitted Paul's head just as a stiff straw hat would that was a size too big for him. The circle of cardboard dropped down until it rested on Paul's ears and on the bridge of his nose. This cardboard brim represented the "plane of the earth's equator," just as the pane of glass represented the "plane of the ecliptic." Since the "plane of the equator" is always at right angles to the slanting axis of the earth, the "plane of the equator" is always at a slant to the "plane of the ecliptic."

If you will run a long hat-pin through an orange, and sink the orange exactly to its middle in a glass bowl filled with water, holding the hat-pin at a slant, you will see that the equator of the orange is at a slant with the surface of the water. Half of the orange's equator curves up above the water, while half of it curves down under the water's surface. If you fasten a cardboard ring around the orange at the equator the cardboard will then be at an angle with the surface of the water, which represents the "plane of the ecliptic."

Uncle Henry cut two long strips from what was left of the cardboard and crossed the strips over the top of Paul's head, fastening the four ends of them to the round cardboard brim close to his head.

After this Uncle Henry rolled a sheet of the scratch paper round a pencil, put rubber bands tightly around it, cut the end to bend up and make a foot and pinned the foot to the cardboard strips at the place where they crossed. When Paul had it all on he looked very funny with the pencil sticking straight up from the top of his head, and his eyes just peeping over the cardboard brim on each side of the strip down the middle of his nose.

"Now come on, Mr. Earth," said Uncle Henry, "It's time for you to spin round the lamp-sun for another year or two."

So Paul held his head on a slant and kept it so that the pencil always pointed in the same direction as he went round the lamp. These four little pictures show how he looked at the four sides of the sun where the earth is in Winter, Spring, Summer, and Autumn.

"Now," said Uncle Henry, "you see that if we make a black dot on one of the cardboard strips about halfway between the cardboard brim, or the earth's equator, and the pencil, or the North Pole, it will be about as far north as we are in the United States. And when Paul is in his Summer position, with the pencil slanting _toward_ the 'sun,' you see that the sun's rays beat down much straighter on the black dot than they do when he is on the other side of the lamp, with the pole slanting _away_ from the 'sun.' That is why the Winter sun appears to be lower in the sky at noon than the Summer sun, and also why the Summer sun shines hotter on the earth than it does in Winter. Notice, too, that the rays from the lamp light up Paul's head for quite a little way beyond the foot of the 'pole' when it slants _toward_ the 'sun,' while when it slants _away_ from the 'sun' the rays fail to reach the 'pole' at all. This means that in summer the sun shines a longer time upon the part of the earth that slants toward it. If you could look down from the ceiling at Paul's head in his Summer position and in his Winter one you would see why."

Uncle Henry quickly drew these two pictures of the top of a globe to show the children why the days are long in Summer and short in Winter at any point in the United States.

"It's just like the hot water bottle mother kept in my bed that time I had a chill after swimming," said Paul. "The hotter it was before she put it in the bed the slower it cooled off."

"That's the idea," said Uncle Henry, "the longer the sun shines on any place on the earth the hotter it gets, and when the nights are as short as they are in Summer the place hasn't long to cool off before it is round in the sun's hot rays again. Now do you see why Summer is hotter than Winter?"

The children did.

"There's one thing I don't understand, though," said Peter. "Why are there different stars in the sky in Winter than there are in Summer?"

"That's easy to answer," said Uncle Henry. "Look at Paul again--first when it's 'night' on his face on the 'Summer' side of the lamp, and then when it is 'night' on his face on the 'Winter' side of the lamp.

"At 'night' in Summer Paul looks at the pictures on one end of the room. The cardboard brim, or 'plane of the equator,' is slanted _up_, above the 'plane of the ecliptic.'"

This picture shows how Paul looked.

"But in Winter, at 'night,' Paul looks at quite different pictures, at the other end of the room. The cardboard brim is slanted _down_, below the level of the 'plane of the ecliptic.' This is why the path of the Winter Signs crosses the sky higher up than the path of the Summer Signs. In both Winter and Summer you must imagine the cardboard brim to be as transparent as glass, for the 'plane of the equator' is in reality only imaginary."

This next picture shows how Paul looked at the constellations at "night" in Winter.

"Of course the north star and the stars for a considerable distance round the pole never set, and can be seen all night at any time of the year. It is only the ones that rise and set that go and come from our sight with the seasons. In reality they never leave us, for if it wasn't for the sunlight getting in our eyes by day, we could see the Summer night star-pictures in the Winter daytime, and the Winter night star people in the Summer daytime. We are just looking at opposite ends of our big room in the universe on Winter nights and Summer nights, that's all," said Uncle Henry.