## Why is it better to launch a spaceship from near the equator?

When a spacecraft is launched into orbit, it should end up spinning around the Earth quickly enough not to be pulled back in by the Earth's gravity. The huge rockets used in launching a spaceship help this to happen by giving a huge amount of thrust, enough to achieve escape velocity. However, the spin of the Earth itself can help give it a push as well. Anything on the surface of the Earth at the equator is already moving at 1670 kilometers per hour. If a ship is launched from the equator it goes up into space, and it is also moving around the Earth at the same speed it was moving before launching. This is because of inertia. This speed will help the spacecraft keep up a good enough speed to stay in orbit.

Why the equator? Believe it or not, the surface of the Earth is traveling faster there. If you look at two spots on one line from pole to pole, one spot on the equator and the other halfway to the pole, each will make a complete revolution in 24 hours and return to where it was. But since the Earth's shape is round, and the widest point is at the equator the spot on the equator would have to go more miles in that twenty four hours. That means that the land is moving faster at the equator than any other place on the surface of the Earth.

The land at the equator is moving 1670 km per hour, and land halfway to the pole is only moving 1180 km per hour, so launching from the equator makes the spacecraft move almost 500 km/hour faster once it is launched.