Create your free account or Sign in to continue. See Subscription Options. Go Paperless with Digital. George Spagna, chair of the physics department at Randolph-Macon College, explains. Get smart. Sign Up. Support science journalism. Knowledge awaits. See Subscription Options Already a subscriber? Create Account See Subscription Options.
Continue reading with a Scientific American subscription. As Mars orbits the Sun, it completes one rotation every Martian days are called sols — short for "solar day. Mars' axis of rotation is tilted 25 degrees with respect to the plane of its orbit around the Sun. This is another similarity with Earth, which has an axial tilt of Like Earth, Mars has distinct seasons, but they last longer than seasons here on Earth since Mars takes longer to orbit the Sun because it's farther away.
And while here on Earth the seasons are evenly spread over the year, lasting 3 months or one quarter of a year , on Mars the seasons vary in length because of Mars' elliptical, egg-shaped orbit around the Sun.
Spring in the northern hemisphere autumn in the southern is the longest season at sols. Autumn in the northern hemisphere spring in the southern is the shortest at days. Mars has two small moons, Phobos and Deimos , that may be captured asteroids. They're potato-shaped because they have too little mass for gravity to make them spherical.
Phobos, the innermost and larger moon, is heavily cratered, with deep grooves on its surface. It is slowly moving towards Mars and will crash into the planet or break apart in about 50 million years.
Deimos is about half as big as Phobos and orbits two and a half times farther away from Mars. Oddly-shaped Deimos is covered in loose dirt that often fills the craters on its surface, making it appear smoother than pockmarked Phobos.
Mars has no rings. However, in 50 million years when Phobos crashes into Mars or breaks apart, it could create a dusty ring around the Red Planet.
When the solar system settled into its current layout about 4. Mars is about half the size of Earth, and like its fellow terrestrial planets, it has a central core, a rocky mantle, and a solid crust. Mars has a dense core at its center between and 1, miles 1, to 2, kilometers in radius. It's made of iron, nickel, and sulfur. Surrounding the core is a rocky mantle between and 1, miles 1, to 1, kilometers thick, and above that, a crust made of iron, magnesium, aluminum, calcium, and potassium.
This crust is between 6 and 30 miles 10 to 50 kilometers deep. The Red Planet is actually many colors. At the surface, we see colors such as brown, gold, and tan. This dust gets kicked up into the atmosphere and from a distance makes the planet appear mostly red.
Its volcanoes, impact craters, crustal movement, and atmospheric conditions such as dust storms have altered the landscape of Mars over many years, creating some of the solar system's most interesting topographical features. A large canyon system called Valles Marineris is long enough to stretch from California to New York — more than 3, miles 4, kilometers. This Martian canyon is miles kilometers at its widest and 4. That's about 10 times the size of Earth's Grand Canyon.
This maximizes their time with the equipment, but drastically changes their actual Earth schedule. Mars is a well studied planet. As a matter of fact, it is the best understood planet in our Solar System other than our own. With all of the data accumulated, Mars rotation is only one of thousands of facts known about the planet.
Here are a few more. How do scientists know the difference? When the ice is exposed to the Martian atmosphere, carbon dioxide ice dry ice will melt and vaporize quickly, in one day or less. Water ice will take up to four days.
The other way is to heat a sample in one of the tiny ovens aboard a rover. The spectrometer on the rover will then be able to detect H 2 O in the gases that the sample releases.
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