This drawing illustrates "eccentricity".
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Martian Orbital Eccentricity
The Martian climate is more influenced by the shape of the Martian orbit than the climate of the Earth is influenced by the shape of the Earth's orbit. The orbit of Mars is more elliptical than that of the Earth. The departure of the Martian orbit from that of a perfect circle is known as the *eccentricity* of the orbit. (It was the large eccentricity of the Martian orbit which forced Kepler to finally abandon his idea that the orbits of the planets were required to be perfectly circular.)
Because the Martian orbit has large excursions from a standard distance from the sun, the surface of Mars can experience larger changes in temperature over the course of a Martian year than does the Earth.
Most importantly for the climate of Mars, the inclination of the axis of revolution of Mars is much more extreme than that of the Earth. This means that differences between summer and winter of Mars can be more extreme than on Earth.
The high eccentricity of the Martian orbit, combined with the high inclination of the axis of revolution, means that, if conditions are just right, there are times when Mars can experience a great deal more warming than normal. These large excursions in the warming of the surface of Mars means that Mars has more potential for climate change induced by orbital parameters than does the Earth.
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