||Department of Physics
||User's Guide to the Night Sky
Motion of the Inner Planets
The animation shows the inner solar system as seen from
a viewpoint high above the plane of the solar system
in a northwards direction. This is effectively
high above the Earth's north pole. As seen from this observing
viewpoint the planets orbit anticlockwise.
From the Sun,
the planets are Mercury, Venus, Earth and Mars.
The closer the planet is to the Sun the faster it orbits.
Relative to the distant stars the orbital periods
of Mercury, Venus, Earth and Mars
87.97 days, 224.70 days, 365.25 days (1 year)
and 1.881 years respectively.
The animation repeats after one synodic period of
Mars, i.e. 780 days.