Mars has seasons chiefly because its rotation axis is tilted by about 25 degrees, close to Earth’s 23.4-degree tilt. As Mars moves around the Sun, each hemisphere alternately receives more direct sunlight and longer days. Its more elliptical orbit also influences how intense and how long each season is.
One Martian year lasts 687 Earth days
Mars requires around 687 Earth days to orbit the Sun once. It also spins with a rotation period similar to Earth’s: a Martian solar day, called a sol, lasts roughly 24 hours and 39 minutes. Therefore a year on Mars is about 669 sols long. Spring, summer, autumn and winter extend across this longer year.
The NASA Mars facts give an axial tilt near 25 degrees and a year of approximately 687 Earth days.
Why a tilted axis produces seasons
Imagine a spinning globe tilted toward a lamp. During one part of the orbit, northern latitudes face the lamp more directly and receive longer periods of daylight. Six months—or half a year—later the opposite hemisphere gets that advantage. Mars follows the same underlying principle as Earth: the tilt, rather than simply moving closer to the Sun, is the primary reason seasons occur.
Why the southern and northern seasons differ
Mars follows a more elongated orbit than Earth. According to Kepler’s laws, it moves faster when closer to the Sun and slower when farther away. That means its seasons are not equal in duration. NASA reports northern spring of roughly 194 sols and northern autumn of about 142 sols. The northern summer occurs when Mars is farther from the Sun, while southern summer occurs closer to the Sun and tends to have stronger seasonal contrasts.
The NASA planetary seasons explanation details these differences and why a Martian calendar cannot simply copy Earth’s twelve months.
What changes on Mars as the seasons pass?
Carbon dioxide can freeze on the surface in polar winter, then sublimate when sunlight returns. Seasonal winds lift fine dust into the atmosphere, sometimes creating enormous storms. Temperatures, air pressure and atmospheric circulation also vary. Orbital spacecraft and rovers monitor the appearance of polar frosts, changes in the sky and movement of dust.
Does summer make Mars warm enough for humans?
Even a relatively warm afternoon near the equator would not make Mars safe for unprotected people. Its atmosphere is very thin and mostly carbon dioxide, and the nighttime temperature can be extremely cold. The seasonal labels describe solar energy and temperature patterns, not Earth-style outdoor comfort.
For more about the planet, see Facts About Mars. To learn how the atmospheric dust affects color, read Why Are Sunsets Blue on Mars?
Frequently asked questions
Does Mars have four seasons? Yes, each hemisphere experiences a recognizable spring, summer, autumn and winter cycle.
Are Martian seasons exactly twice as long as Earth’s? No. The full year is almost twice as long, but its individual seasons are unequal.
Does the distance from the Sun cause Martian seasons? Axial tilt is the primary cause, while orbital distance modifies intensity and length.
Do both Martian hemispheres have summer at once? No. When one has summer, the other has winter.
Are there seasonal polar caps? Yes. Seasonal carbon dioxide frost grows and retreats, overlying longer-lived polar ice.
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