When asked what keeps a satellite up, both children and adults typically answer that satellites are beyond the pull of Earth's gravity.
Satellites actually remain in orbit about Earth because of gravity.
More than 300 years ago the scientific foundations for satellites were laid when Isaac Newton discovered the Universal Law of Gravitation. He reasoned that the pull of the Earth that causes an apple to fall to the ground also extends out into space to pull on the Moon as well. Newton expanded on this discovery and hypothesized how an artificial satellite could be made to orbit the Earth. He envisioned a very tall mountain extending above Earth's atmosphere so that friction with the air would not be a factor. He then imagined a cannon at the top of that mountain that fired cannonballs parallel to the ground.