Relative motion Earth-planet
On the left side of the screen the simulation shows the motion of the Earth and of a
planet around the Sun. The circumferences formed with points and with the Sun in the centre
represent the vault of the heaven.
On the right side of the screen it is possible to see the motion of the planet as it is
seen from the Earth.
Because of the different period of revolution, for a certain period of time, we observe
an inversion of the motion (retrograde) of the planet in relation to the Earth.
On the tool bar it is possible to choose between a planet inside the terrestrial orbit
(Mercury) and an external orbit (Mars).
In the case of the external planet, by clicking on button , it is possible to draw a line that, starts from the Earth, crosses Mars and
continues to the vault of the heaven. This helps to understand the motion of Mars seen from the Earth
and in particular the retrograde motion.
By clicking the button it is possible
to start a new simulation.
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