Why do satellites remain in orbit around Earth?

Satellites remain in orbit around Earth due to the balance between their forward motion and Earth's gravitational pull.

In more detail, the concept of satellites remaining in orbit around the Earth is a fascinating application of Newton's laws of motion and universal gravitation. The first key principle to understand is that a satellite, like any object moving in a circle, is constantly changing its direction and therefore is always accelerating. This acceleration is provided by the force of gravity.

The second principle is that the satellite is moving forward, or tangentially to the Earth. This forward motion is a result of the initial velocity given to the satellite when it was launched. If there were no gravity, the satellite would continue moving in a straight line off into space. However, the Earth's gravity pulls the satellite towards the Earth, causing it to move in a curved path, or orbit.

The balance between this forward motion and the pull of gravity is what keeps the satellite in orbit. If the satellite moves too slowly, it will not have enough forward motion to counteract the pull of gravity and it will fall back to Earth. If it moves too quickly, it will overcome the pull of gravity and move off into space. But if the satellite's speed is just right, it will continue to fall towards the Earth but always miss it, staying in a stable orbit.

This delicate balance is known as the 'gravity turn'. The satellite is constantly 'falling' towards the Earth due to gravity, but its forward motion means it keeps missing the Earth. This is similar to how the Moon stays in orbit around the Earth, or the Earth stays in orbit around the Sun.

In conclusion, the reason satellites remain in orbit around the Earth is due to the balance between their forward motion and the pull of gravity. This is a perfect example of how physics can be used to explain phenomena in the natural world.