Part 21 (1/2)
In order to cover the distance that separates us froht_, the most rapid of all couriers, takes 4 years, 128 days If ould follow it, we ive us the faintest idea of the distance: we must take the trouble to think out the direct advance of the ray of light, and associate ourselves with its progress Wethe first second of the journey; then 300,000 more in the second, which makes 600,000 kilo the third, and so on without stopping for four years and four months If we take this trouble we ure; otherwise, as this nu, it will have no significance for us, and will be a dead letter
If so explosion occurred in this star, and the sound in its flight of 340 meters (1,115 feet) per second were able to cross the void that separates us from it, the noise of this explosion would only reach us in 3,000,000 years
A train started at a speed of 106 kilometers (65 miles) per hour would have to run for 46,000,000 years, in order to reach this star, our neighbor in the celestial kingdom
The distance of some thirty of the stars has been deter Sirius reigns 92,000,000,000,000 kiloa at 204,000,000,000,000 Each of these e sun to burn at such a distance with such luer than the Earth
Most of them are more voluminous than our Sun On all sides they scintillate at inaccessible distances, and their light strays a long while in space before it encounters the Earth The luminous ray that we receive to-day from some pale star hardly perceptible to our eyes--so enor us the last eo
If these methods have been clear tothethe worlds
The process is as si
_Weighing the stars!_ Such a pretension seems Utopian, and one asks oneself curiously what sort of balance the astronoht of Sun, Moon, planets or stars
Here, figures replace weights Ladies proverbially dislike figures: yet it would be easier for soh the Sun at the point of her pen, by writing down a few coluram case of fruit, or a dress-basket of 35 kilos, by directthe Sun is an ae of occupation
If the Moon were not attracted by the Earth, she would glide through the Heavens along an indefinite straight line, escaping at the tangent But in virtue of the attraction that governs the movements of all the Heavenly bodies, our satellite at a distance of 60 times the terrestrial half-diameter revolves round us in 27 days, 7 hours, 43 ht line to approach the Earth, and describing an almost circular orbit in space If at any ent is taken to this arc, the deviation froht line caused by the attraction of our planet is found to be 1-1/3 millimeter per second
This is the quantity by which the Moon drops toward us in each second, during which she accomplishes 1,017 meters of her orbit
On the other hand, no body can fall unless it be attracted, drawn by another body of a s, anih upon the Earth, because they are constantly attracted to it by an irresistible force
Weight and universal attraction are one and the same force
On the other hand, it can be determined that if an object is left to itself upon the surface of the Earth, it drops 490the first second of its fall
We also know that attraction diminishes with the square of the distance, and that if we could raise a stone to the height of the Moon, and then abandon it to the attraction of our planet, it would in the first second fall 490 meters divided by the square of 60, or 3,600--that is, of 1-1/3 millimeters, exactly the quantity by which the Moon deviates froht line she would pursue if the Earth were not influencing her
The reasoning just stated for the Moon is equally applicable to the Sun
The distance of the Sun is 23,386 times the radius of the Earth In order to kno ht would be diminished at such a distance, we should look, in the first place, for the square of the nu the distance--that is, 23,386 multiplied by itself, = 546,905,000 If we divide 490 meters, which represents the attractive force of our planet, by this nuet 9/1000000 of a millimeter, and we see that at the distance of the Sun, the Earth's attraction would really be almost _nil_
Now let us do for our planet e did for its satellite Let us trace the annual orbit of the terrestrial globe round the central orb, and we shall find that the Earth falls in each second 29 ives the attractive force of the Sun in relation to that of the Earth, and proves that the Sun is 324,000 times more powerful than our world, for 29 millimeters divided by 0000,009 equals 324,000, if worked out into the ultilected here for the sake of sihed by the same method
Their mass is estimated by the movement of a satellite round them, and it is by this method that we are able to affirm that Jupiter is 310 times heavier than the Earth, Saturn 92 times, Neptune 16 times, Uranus 14 ti only two-thirds that of our own