The Moon : the Earth's satellite

From a point of view located on the Earth, the Moon revolves around us with a period of about 27,5 days.
The Moon changes phases (new, waxing, full and waning Moon) with a period of about 29,5 days (the month was originated from this observation). This period is different than the former because it has to do with the relative positions of three bodies: the Sun, the Earth and the Moon. The Moon is full when it is almost opposite to the Sun from the Earth.
From a point of view located on the Sun, the Moon is dragged by the Earth's revolution around the Sun, describing a wavy ellipse, almost identical to the Earth's orbit. The Moon's position changes with a period of about 27,5 days: sometimes (at new Moon) the Moon is nearer the Sun that the Earth; sometimes (at full Moon) it is farthest; sometimes (in the half quarters) it is at about the same distance.

You can see a simulation of the Moon's orbit by pressing the Continue button below. Pressing the Stop button stops the simulation.

A photograph of the Moon (by courtesy of NASA).


Course pages:
Newton's Mechanics
The Solar system
The Earth-Moon system
The Discovery of Neptune
Let's experiment with the inner system
A satellite roll-axis control system
A geostationary satellite

Other courses
Gravitation
Ecology
Electronics
PDEs
Other pages

Last modified 22/12/99 by Juan de Lara ( Juan.Lara@ii.uam.es, http://www.ii.uam.es/~jlara) need help for using this courses?.

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