Observe the sun and the rotation of the planets in this moving image from NASA. Observe the axial tilts and directional rotation of planets and how they differ for each planet. Be sure to read the background information on how planets...

The mathematics associated with the motion of satellites is described. Equations (for period, velocity, acceleration and force) are stated, symbols described, and sample problems solved. Includes five practice problems with solutions and...

The three laws of planetary motion as described by Kepler are stated and elaborated upon. Useful graphics and an easy-to-understand language are used to explain the nature of planetary motion. Both conceptual and mathematical. Includes a...

This is the home page of the team that built the Ultraviolet Imaging Spectrograph carried by the Cassini mission to Saturn.

Discusses the information from the NASA spacecraft Messenger as it orbits Mercury and transmits photographs of the planet's surface to Earth.

This site describes the extended belt of small bodies residing just outside the orbit of Pluto, the Kuiper Belt.