What keeps sputnik in its orbit?
The Soviet “moon” is circling the earth in an orbit that, at times at least, carries it more than 500 miles away from the earth. It is traveling some 18,000 miles an hour. All the time, like a weight dropped from an airplane, it is “trying” to fall to the ground under the ever-present pull of gravity, which is approximately the same at that altitude as it is nearer the earth. However, because of its high speed, the satellite does not fall, but goes into an orbit whose exact shape has not yet, in this case, been defined with precision. The satellite’s velocity at any given moment is in a direction parallel to the ground. If there were no gravity, it would fly off, away from the earth’s sphere, in a straight line. But with gravity at work, the resultant balance between the satellite’s tendency to shoot off on a tangent, because of its velocity, and its tendency to fall under gravity is the orbit in which it goes on round and round the earth. Thus, the satellite’s orbit depends a good dea
