Lynne P. Scott, age 12, of Vancouver, .‑G., for her questions
Does the sun have more gravity than the earth?
Gravity hugs us to the ground and gives us weight, It is a mysterious and invisible force: But, like everything else in this orderly universe, it has to keep certain laws. The sun, moon, stars and every speck of matter each has its quota of gravitation. So much and no more. What's mores the power of gravitation changes with distance. The very center of its power is in the very center of the mass, or weight of an object or heavenly body. At this center of gravity, the power of gravity is strongest, It weakens the further it gets from this point„
The more mass in a body, the greater its gravitation. Gravity is what the mysterious force does to objects on its surface: So, in order to estimate this, we must estimate the weight, or mass of a heavenly body and also its radius, A ten ton ball of feathers might have the same power of gravitation as a ten ton ball of lead, But it would be must bigger and therefore its surface would be much farther away from its center of gravity, Its surface gravity would be somewhat weaker,
In order to compare the surface gravity of the earth with the surface gravity of the sun, we must know their weights and sizes. Fortunately this measuring job has been done for us. 'trite the number 6,570 and follow it with 18 zeros. That is the weight of the world in tons, It includes. everything deep within the earth, the rocks,. seas and mountains on the surface, along with all the trees, people, buildings and.the air above. Now multiply that big number of tons by 333,400 and you have the weight, or mass of the sun. ‑
Does this mean that the sun is only, 333,400 times as big as the earth? Not at all. Remember the ball of feathers and the ball of lead. Taken altogether, inside and out, the earth is about 51 times heavier than water. Taken, altogether, inside, and out, the sun is a little less than one and a half times, as heavy as water. The sun takes up as much space as 1.,300,000 earths, Its diameter is 865x000 miles. This is about 109 times longer than the diameter of the earth. The radius is half the diameter and the radius of the sun or the earth is the distance from the center of gravity to the surface.
The sun is made of less dense materials than the earth. Its center of gravity is over 100 times further from its surface ‑ this magic power decreases with distance. Bit you would be wrong if you guessed that the surface gravity of the earth could compare with that of the sun. Let's take another look at the mass of the sun. Suppose the whole Solar System, sun, planets, moons, comets and floating dust, were weighed together. Now divide that huge number of tons into 700 parts. The sun takes all but one of these parts. About 99 and 6/7 of all the mass in the Solar System is in the sun. Imagine the power of its gravitation!
At the surface of the sun, the force of gravity is over 27 and 1/2 times that of the earth, Suppose you weigh one hundred pounds. This means that the surface gravity of the earth exerts 100 pounds worth of pull on your body Now suppose you could stand on the face of the sun ‑ which, of course, is impossible, There your 100 pound body would weigh 2,760 pounds Anything weighing 100 pounds on earth would weigh nearly one and a half tons on the sun.