CONTENTS.
| [LECTURE I.] | |
| THE SUN. | |
| PAGE | |
| The Heat and Brightness of the Sun—Further Benefits that we receive from the Sun—The Distance of the Sun—How Astronomers measure the Distances of the Heavenly Bodies—The Apparent Smallness of Distant Objects—The Shape and Size of the Sun—The Spots on the Sun—Appearances seen during a Total Eclipse of the Sun—Night and Day—The Daily Rotation of the Earth—The Annual Motion of the Earth round the Sun—The Changes of the Seasons—Sunshine at the North Pole | 1 |
| [LECTURE II.] | |
| THE MOON. | |
| The Phases of our Attendant the Moon—The Size of the Moon—How Eclipses are produced—Effect of the Moon’s Distance on its Appearance—A Talk about Telescopes—How the Telescope aids us in Viewing the Moon—Telescopic Views of the Lunar Scenery—On the Origin of the Lunar Craters—The Movements of the Moon—On the Possibility of Life in the Moon | 74 |
| [LECTURE III.] | |
| THE INNER PLANETS. | |
| Mercury, Venus, and Mars—How to make a Drawing of our System—The Planet Mercury—The Planet Venus—The Transit of Venus—Venus as a World—The Planet Mars and his Movements—The Ellipse—The Discoveries made by Tycho and Kepler—The Discoveries made by Newton—The Geography of Mars—The Satellites of Mars—How the Telescope aids in Viewing Faint Objects—The Asteroids, or Small Planets | 134 |
| [LECTURE IV.] | |
| THE GIANT PLANETS. | |
| Jupiter, Saturn, Uranus, Neptune—Jupiter—The Satellites of Jupiter—Saturn—The Nature of the Rings—William Herschel—The Discovery of Uranus—The Satellites of Uranus—The Discovery of Neptune | 212 |
| [LECTURE V.] | |
| COMETS AND SHOOTING STARS. | |
| The Movements of a Comet—Encke’s Comet—The Great Comet of Halley—How the Telegraph is used for Comets—The Parabola—The Materials of a Comet—Meteors—What becomes of the Shooting Stars—Grand Meteors—The Great November Showers—Other Great Showers—Meteorites | 255 |
| [LECTURE VI.] | |
| STARS. | |
| We try to make a Map—The Stars are Suns—The Numbers of the Stars—The Clusters of Stars—The Rank of the Earth as a Globe in Space—The Distances of the Stars—The Brightness and Color of Stars—Double Stars—How we find what the Stars are made of—The Nebulæ—What the Nebulæ are made of—Photographing the Nebulæ—Conclusion | 318 |
| [CONCLUDING CHAPTER.] | |
| HOW TO NAME THE STARS. | 381 |
STAR-LAND.
LECTURE I.
THE SUN.
The Heat and Brightness of the Sun—Further Benefits that we receive from the Sun—The Distance of the Sun—How Astronomers measure the Distances of the Heavenly Bodies—The Apparent Smallness of Distant Objects—The Shape and Size of the Sun—The Spots on the Sun—Appearances seen during a Total Eclipse of the Sun—Night and Day—The Daily Rotation of the Earth—The Annual Motion of the Earth round the Sun—The Changes of the Seasons—Sunshine at the North Pole.
THE HEAT AND BRIGHTNESS OF THE SUN.
We can all feel that the sun is very hot, and we know that it is very big and a long way off. Let us first talk about the heat from the sun. On a cold day it is pleasant to go into a room with a good fire, and everybody knows that the nearer we go to the fire, the more strongly we feel the heat. The boy who is at the far end of the room may be shivering with cold, while those close to the fire are as hot as they find to be pleasant. If we could draw much nearer to the sun than we actually are, we should find the heat greatly increased. Indeed, if we went close enough, the temperature would rise so much that we could not endure it; we should be roasted. On the other hand, we should certainly be frozen to death if we were transported much further away from the sun than we are now. We are able to live comfortably, because our bodies are just arranged to suit the warmth which the sun sends to that distance from it at which the earth is actually placed.
Suppose you were able to endure any degree of heat, and that you had some way of setting out on a voyage to the sun. Take with you a wax candle, a leaden bullet, a penny, a poker, and a flint. Soon after you have started you find the warmth from the sun increasing, and the candle begins to get soft and melt away. Still, on you go, and you notice that the leaden bullet gets hotter and hotter, until it becomes too hot to touch, until at last the lead has melted, as the wax had previously done. However, you are still a very long way from the sun, and you have the penny, the poker, and the flint remaining. As you approach closer to the luminary the heat is ever increasing, and at last you notice that the penny is beginning to get red-hot; go still nearer, and it melts away, and follows the example of the bullet and the candle. If you still press onwards, you find that the iron poker, which was red-hot when the penny melted, begins to get brighter and brighter, till at last it is brilliantly white, and becomes so dazzling that you can hardly bear to look at it; then melting commences, and the poker is changed into liquid like the penny, the lead, and the wax. Yet a little nearer you may carry the flint, which is now glowing with the same fervor which fused the poker, but even the flint itself will have to yield at last and become, not merely a liquid like water, but a vapor like steam.