Martian summer begins in the northern hemisphere on the 30th March, 2012.
Mars has an axial tilt of 25.2°. This means that there are seasons on Mars, just as on Earth. The eccentricity of Mars' orbit is 0.1, much greater than the Earth's present orbital eccentricity of about 0.02. The large eccentricity causes the insolation on Mars to vary as the planet orbits the Sun (the Martian year lasts 687 days, roughly 2 Earth years). As on Earth, Mars' obliquity dominates the seasons but, because of the large eccentricity, winters in the southern hemisphere are long and cold while those in the North are short and warm.
The seasons present unequal lengths are as follows:
Season
Sols (on Mars)
Days (on Earth)
Northern Spring, Southern Autumn:
193.30
92.764
Northern Summer, Southern Winter:
178.64
93.647
Northern Autumn, Southern Spring:
142.70
89.836
Northern Winter, Southern Summer:
153.95
88.997
Precession in the alignment of the obliquity and eccentricity lead to global warming and cooling ('great' summers and winters) with a period of 170,000 years.
