How Do Objects Orbit The Earth?
To understand why satellites orbit the earth you first need to understand Newton's Law of Inertia. All objects want to maintain their state of motion (if they are moving they want to continue moving in a straight line) This means if a cannon were to fire a projectile off a cliff the object would maintain a forward state of motion while gravity pulled it down.
If a cannon were positioned on an impossibly tall mountain on earth and fired, the cannonball would have the same curved path.
| This cannonball will make it further around the earth the faster it is fired. If it is fired at a fast enough rate, it will get pushed forward the same distance that the cannonball is pulled toward the Earth by gravity. This means that it will circle the entire Earth. It will not stop circling the Earth until its forward speed decreases. Decreasing the object's speed would cause it to fall. It would not go as far forward as it gets pulled down by gravity. |
Newton made this realization while thinking of the moon's orbit around the earth. He realized that the moon fell toward the Earth about 1020 meters every second. It also moves forward 1020 meters every second. This means the moon will fall around the earth in a circle.
The next question that comes to mind is: Do satellites have to move at certain speeds to continue orbiting the earth?