What concept did Isaac Newton derive for a projectile to leave Earth's gravity?

Isaac Newton derived the concept of escape velocity for a projectile to leave Earth’s gravity.

His famous thought experiment imagined a cannon placed on a very tall mountain. A cannonball fired horizontally at modest speed would fall back to Earth, while faster shots would travel farther. At the right speed, the ball would continually fall around the curved Earth and enter orbit. At a still higher threshold, it would have enough kinetic energy to move away without returning: the idea now called escape velocity.

For an ideal launch from Earth’s surface, ignoring air resistance and rotation, escape velocity is about 11.2 kilometers per second. It depends on the attracting body’s mass and the launch distance from its center, so the value is different for the Moon, Mars, or a higher launch altitude.

Escape velocity is often confused with orbital velocity. Orbital velocity keeps an object bound in a closed path; escape velocity is the minimum initial speed for an unpowered object to reach arbitrarily far away from the body’s gravity.