3 - 02 Rotation on an Axis

day

The 24 hour period during which Earth makes one complete rotation in which each face of the earth receives hours of light while facing the sun, and hours of dark while facing away from the sun.

planet

A celestial body moving in orbit around a star, which is spherical in shape, and has enough mass to clear its orbit of other similar sized bodies. Earth is one of these.

rotation

The spinning of an object such as a planet on its central axis.

axis

An imaginary line through the center of an object, about which the object will rotate. Earth's runs between the North and South Poles.

revolution

The movement of one object in a circular or elliptical path around another object. Planets revolve around a star. Natural satellites revolve around planet.

orbit

The circular or elliptical path an object follows as it revolves around another object.

natural satellite

A naturally existing celestial body that revolves around a planet.

elliptical

oval-shaped, like a flattened circle

gravitational pull

The pull that exists between all objects caused by the force of gravity. Larger objects have a larger gravitational pull.