We have found to date that the star we call our Sun has nine satellites or planets and what appears to be a host of fragments of another. We call these fragments the “asteroids.” In the order of their distance from the Sun these bodies are Mercury, Venus, Earth, Mars, the asteroids, Jupiter, Saturn, Uranus, Neptune, and Pluto. Mercury, Venus, and Mars have been known from remote ages. They, like Earth, are all relatively small bodies, and these four are known as the “minor planets.” Jupiter, Saturn, Uranus, and Neptune are all very much larger and are known as the "major planets." Pluto was discovered only in 1930, and about all we know of it so far is that it is small, probably smaller than our Earth, and roams away out in cold space some forty times as far from the Sun as we are. Whether there are still other planets even beyond Pluto, we do not know. Some astronomers suspect there are. A queer gap exists after Mars is passed and before Jupiter is reached. This gap is occupied by the asteroids. There seems to be reason for believing that a primordial planet once existed here, which, owing to its hiving once ventured too near to Jupiter, burst, and the fragments are the asteroids which we who came later now see. We became aware of their existence only as recently as r8or. The largest fragment we have thus far located is about 480 miles in diameter. We have given it the name Ceres. We have located only four having diameters in excess of 100 miles. We have no knowledge of the number of fragments, but we know there is a swarm of them. Jupiter, by reason of its enormous size, being by far the largest of the planets, is conspicuous in the sky and has been known from antiquity. Saturn, which is next, is also large and conspicuous and has been known for centuries. When telescopes came into use, Saturn was found to be encircled by a mysterious ring. It is now clearly established that this ring is composed of the fragments of a moon which became shattered by gradually being drawn too close to Saturn. Uranus is a relatively recent discovery. Neptune's existence was predicted from certain suspicious movements of Uranus. The latest addition to the family, Pluto' was also predicted but not immediately located.
Having thus made the casual acquaintance of our celestial brothers and sisters let us become more intimate with each of them. They are our blood relatives' our nearest cosmic neighbors, and some of them are relatively so very near that we are able to study them in detail. Familiarity with them will assist us in. forming an idea Of those clouds of more distant fellow inhabitants of the cosmos.
In Figure 2 and its accompanying table we have all nine members of our solar family and the sad remains of the tenth. A very rough approximation of relative diamters is shown. No attempt is made to show our parent Sun. The distance of each planet from the Sun is given roughly in millions of miles and also in light minutes. Light seems to have a fixed velocity. Under all circumstances it appears to travel at a speed of about 186,000 miles per second. We have difficulty in comprehending such a velocity. An automobile traveling at 60 miles and hour we regard as moving at high speed. Yet 60 miles an hour is only and and two-thirds hundredths of a mile per second. To get up to a single mile in a second means that we must move along at the rate of 3,600 miles per hour. This means from Chicago to London in an hour. Light would travel from Chicago to London in two hundredths of a second. We may faintly comprehend the speed of light, 186,000 miles per second, from this.
Light takes 8.3 minutes to make the journey from the Sun to Earth. It fololows that if anything happens on the Sun, we do not see it on Earth until 8.3 minutes after it has happened. Expressed in another way, when we are looking at the Sun, we do not see what may be going on there. Instead, we see only what went on 8.3 minutes ago. This is quite important when we come to photograph nebulae that are a million light years away. A photograph made to-night shows what they were a million years ago. There is no possible way of knowing what things are like in the cosmos now. Cosmically speaking, there is no such thing as now. Now-here means something. It means the present time on Earth. But if we look across the cosmos now at a nebula a million light years away, we see the nebula as it was a million years ago. Now here on Earth is a million years different from flow on Nebula M31. From this Dr. Einstein has built up his conception that "time" means nothing and "space" means nothing and that the only thing that has real meaning is where-when, or, as it is termed, "space-time." Returning to our little family of solar satellites, we notice that our newly found little brother Pluto is so far out in space that it takes light 5 hours and 34 minutes to reach him from the Sun, instead of only 8.3 minutes in the case of our Earth. This means that little Pluto has a very large orbit compared with ours. In our Earth's case, since we are 8.3 light minutes from the Sun and we travel once around the Sun in approximately 365 days, it fol- lows that our path, or orbit, must have a diameter of twice 8.3 light minutes, or 16.6 light minutes. This means that the circumference of our orbit is about 5z light minutes or 58r million miles.
If our Earth travels the enormous distance of 581 million miles in 365 days, it means that it must be swinging around on its orbit at the very respectable rate of 1,600,000 miles per day. We think of speed in miles per hour. Since there are 24 hours in a day, our steady old Earth, with its Empire State Buildings, its cities, continents, oceans and mountains, a total weight in the neighborhood of 6,000 million, million, million tons, is hurling through space at a speed of nearly 67,000 miles an hour, or over a thousand times faster than an automobile or railroad train running a mile a minute. The effect of such a mass moving at such a speed gives some idea of cosmic energy.
Pluto has such a long way to go to cover its orbit that it takes 248 of our years. Such would be the time between birthdays were there children on Pluto. Neptune’s year is 164 of our years, Uranus’s 84, Saturns’s 29, Jupiter’s nearly 12, Mars’ nearly 2, Venus’ 7 ½ months, and Mercury’s only 3 months.
Earth has one satellite, our Moon' Mars has two, Jupiter nine, Saturn nine, Uranus four, and Neptune one. We cannot find any around Pluto. Saturn also has the mysterious ring around it, probably the fragments of a moon which came too close and was burst by the tremendous gravitational pull. One of the moons of Jupiter is perilously close to the critical point where bursting must occur, and any time now during the next million years we shall probably be seeing it burst and gradually form into another ring like Saturn’s.
All the planets and their satellites are composed of the same materials that Earth is made of, as might be expected. We know, because our spectroscope shows the telltale lines that the same elements on Earth show.
Temperatures and atmospheres on the other planets are quite different from those we have on Earth. Mercury is so near the Sun that the enormous gravitational pull has locked the poor little satellite in position, as the Earth has locked its satellite, the Moon. The same face is always turned toward us. We have never seen its other side.
Let us now regard each planet separately.
©2013
W0IS.com
Copyright and Privacy Notice