--------+----------+------------+-------------+-------------+---------- | | Number of | | Time | | | planets | Distance | required | Velocity Name | Diameter |required to | from sun | for one | in orbit, | in miles | equal sun | in millions | revolution | miles per | | in size | of miles | around sun | hour | | | | in days | --------+----------+------------+-------------+-------------+---------- Mercury | 3,008 | 5,000,000 | 36 | 88 | 107,012 Venus | 7,480 | 425,000 | 66 | 225 | 78,284 Earth | 7,926 | 332,260 | 92 | 365-1/4 | 66,579 Mars | 4,999 | 3,093,500 | 141 | 687 | 53,938 Jupiter | 88,439 | 1,048 | 483 | 4,332 | 29,203 Saturn | 75,036 | 3,502 | 886 | 10,759 | 21,560 Uranus | 30,875 | 22,600 | 1,783 | 30,687 | 15,202 Neptune | 37,205 | 19,400 | 2,794 | 60,127 | 12,156 --------+----------+------------+-------------+-------------+----------
The moon is 240,000 miles from the earth, and it would require nearly 24,500,000 moons to equal the sun in size. Other planets have moons, some of them several. If you lived on the planet Mercury, your annual birthday would come around about once in three of our months. If you had your home out on the border land of the solar system, on the planet Neptune, you would have a birthday once in about 165 years, as we count time on the earth. It will be observed that the closer the planet is to the sun, the faster it travels in its orbit. This fact is due to the power of gravitation toward the sun. This strange influence drives the planets around the sun, and the nearer the planet is to the sun the greater is the power and consequently the faster the revolution. The law of gravitation was discovered by Sir Isaac Newton.
Newton was born in 1642 in Lincolnshire, England. His father was a farmer, and the farmhouse in which the son was born is still preserved. He was educated at a grammar school in Lincolnshire, and later entered Trinity College, Cambridge, from which he was graduated in 1665. Early in life he displayed a great liking for mathematics. Within a few years after he entered college, he had mastered the leading mathematical works of the day and had begun to make some progress in original mathematical investigation.
Newton's great life work--the achievement which insured to his name a place among the immortals--was suggested to him by accident. As the story goes, while he was walking one day in a garden, he saw an apple fall from a tree. He speculated upon the reasons for its falling, and ultimately concluded that the same force which causes an apple to fall from a tree holds the heavenly bodies in their places. Further investigation brought him to the unfolding of this general law of gravitation: "Every body in nature attracts every other body with a force directly as its mass, and inversely as the square of its distance." This law is the greatest law of nature. It is the central fact of the physical universe, the cement of the material world, the mighty, mystic shepherdess of space, that keeps the planets from wandering off alone. It is this awful, silent power reaching out from the enormous mass of the sun, that lashes the planets in their furious race, and yet holds them tightly reined in their orbits.