The planet experiences all four seasons that the Earth does, but, since the year is longer on the planet, the axial tilt is different, and Mars has a more eccentric orbit than Earth, the seasons are not the same length as each other or the same in each hemisphere.
Full Answer
This would seem to indicate that the planet formerly had a different degree of axial tilt, which would have made for a much different environment and potential seasonal variations. Mars does have seasons. They are not the same as the seasons the planet experienced millenia ago and may not be the same in the future.
A radar instrument on the Mars Express has turned up water ice, a mineral mapping instrument has discovered chemicals formed in a wet environment, and its camera has picked out features on the surface formed by running water. The cameras also show a huge valley, Kasei Valles, that was probably carved by a gigantic glacier.
On Mars, in the northern hemisphere to be exact, spring is the longest season. The Martian year is nearly twice as long as an Earth year(1.88 years), the seasons last longer as well.
Here is how a Martian year in the north breaks down: Spring…7 months, Summer…6 months, Fall…5.3 months, and Winter…just over 4 months. Even in the summer months it is very cold. Temperatures at the height of the season may not top -20 C.
Its orbital motion is slowest when it is at aphelion (the farthest point from the Sun) and fastest at perihelion (the closest point to the Sun). This makes Martian seasons vary greatly in duration than those on Earth.
Why does Mars have seasons? Because, like Earth, its axis is tilted away from the Sun. On Mars, in the northern hemisphere to be exact, spring is the longest season. The Martian year is nearly twice as long as an Earth year(1.88 years), the seasons last longer as well.
Similarly to Earth, Mars has four distinct seasons. However, each season lasts about twice as long because the Martian year is almost twice that of Earth. Mars orbits closest to the Sun when its southern hemisphere is tilted towards it, while the northern hemisphere is tilted towards the Sun when it is furthest away.
During Southern winter, Mars is farthest away from the Sun in its elliptical orbit around the Sun. That's different from Earth, because our planet has a near circular orbit. Winter in the southern hemisphere is worse, because Mars is the farthest away from the Sun and moves more slowly in its orbit.
Annual changes in temperature on a planet are caused by a combination of two factors: axial tilt and variable distance from the Sun. On Earth, axial tilt determines nearly all of the annual variation, because Earth's orbit is nearly circular.
Overall, Mars is cold—its average global temperature is around -80 degrees Fahrenheit—and has a much thinner atmosphere than Earth. Because it has about a sixth of the pressure of Earth's atmosphere, the planet doesn't retain heat very long, causing temperatures to drop quickly.
On Mars, temperatures swing wildly from one time of year to another, from day to night, and from the surface to the height of a head above it. The planet has two different kinds of seasons that interact throughout the course of a Martian year (nearly two times longer than what we know as a year).
The array of colors we see on Mars is a result of mineral diversity – different minerals have different colors – just like on Earth. In images, some regions appear to have different colors because of shadows, reflected sunlight or even seasonal changes, such as the appearance of permafrost and flow features.
Mars' variations in temperature and its seasonal changes are also related to changes in the planet's orbit. Essentially, Mars' eccentric orbit means that it travels more slowly around the Sun when it is further from it, and more quickly when it is closer (as stated in Kepler's Three Laws of Planetary Motion).
The southern hemisphere also experiences longer, colder winters than the northern hemisphere since Mars is near aphelion during these seasons.
Which statement is the best explanation for seasonality on Mars? The tilt of Mars's axis causes annual variation in the amount of solar radiation received by the northern and southern hemispheres of the planet.
Because, like Earth, its axis is tilted away from the Sun. On Mars, in the northern hemisphere to be exact, spring is the longest season. The Martian year is nearly twice as long as an Earth year (1.88 years), the seasons last longer as well.
A radar instrument on the Mars Express has turned up water ice, a mineral mapping instrument has discovered chemicals formed in a wet environment, and its camera has picked out features on the surface formed by running water.
Here’s an article describing Spirit surviving 1000 days on Mars, going through all the seasons. And another on the discovery of mid-latitude glaciers on Mars, evidence that the planet was much more tilted in the past. Here is some great information from the Adler Planetarium about the Martian climate and seasons.
Mars does have seasons. They are not the same as the seasons the planet experienced millenia ago and may not be the same in the future. Earth has seen the same climate changes. Planetary evolution is ongoing, hopefully the spacecraft on and around the planet will tell us more, soon.
We’ve seen that the seasons are caused by Earth’s axis tilt, not by Earth’s slightly varying distance from the Sun. Still, we might expect the varying orbital distance to play at least some role. Before you continue, explore why by discussing the following in small groups or with your whole class.
Teacher Notes. This is an optional section, but the material is briefly mentioned in the video watched earlier, and some students will find it to be of interest.