Washington: While Northern Hemisphere is celebrating its first day of summer, the Mars rovers Curiosity and Opportunity in Red Planet`s southern hemisphere are enjoying the end of the warm weather season, before the autumn equinox takes place on July 31, next year. The upcoming spring/autumn on Mars will be the Red Planet`s longest season at 194 days and Northern Hemisphere`s equivalent summer solstice won`t occur till February 14, 2014, Discovery News reported. Due to Red Planet`s orbit, the rovers will have to endure longer, colder autumns and winters in the southern hemisphere compared to if they had been in the north. ANI