By Paul Doherty
Senior Staff Scientist
San Francisco, CA
The Three Moons of Earth, scientists have recently discovered two more co-orbital partners of the earth in addition to the Moon: Cruithne a 5 km diameter asteroid in a horseshoe orbit, and 2002AA29, a 100 m diameter asteroid which orbits the earth over the poles.
Gravitational interactions, an explanation of how a planetary gravity assist works using a tennis ball and a basketball. When a tennis ball is dropped on top of a basketball the resulting collision launches the tennis ball at high velocity. The same mechanics applies when a satellite encounters a planet and uses the resulting "collision" to gain speed.
Gravity Wells, many museums have large gravity wells in which balls can be rolled to illustrate orbital mechanics. Different shaped wells such as a straight sided funnel and a spherical bowl produce interesting orbital variations.
Gravity Well Math Root
Stocking Force Visualization
Return to Draft Activities
Scientific Explorations with Paul Doherty
21 August 2003