The sun on Mars is tinted blue at sunrise and sunset—when it’s close to the horizon—and is only about half the size of the sun we’re used to seeing on Earth.
Mars has so little free oxygen in its atmosphere that if you tried to breathe unassisted on its surface, you’d have to inhale 14,500 times to get the same amount of oxygen that you’d get in a single breath on Earth.
Due to solar wind storms eroding the Martian atmosphere over time, Mars has extremely low atmospheric pressure, and is very cold. Because of this, water molecules on Mars can only exist as either solid (ice) or gas (vapor).
Hunks of Mars have hit the Earth. These are rocks ejected from Mars’ surface into space when an asteroid or large meteor strikes the red planet.
Mars has ice caps at the poles, as Earth does, but Mars’ ice caps are composed of frozen carbon dioxide. Although these “dry ice” ice caps survive year round, they are constantly changing their shape.
In the spring, frozen carbon dioxide in Mars’ polar ice caps sublimates (changing directly from solid to gas)—a process which creates these weird, spider-like formations around the north and south poles.
Mars has the tallest mountain in the entire solar system—Olympus Mons, which is 16 miles high. That’s nearly three times the height of Mount Everest, the tallest mountain on Earth.
When viewed from Earth, about a third of Mars is covered with dark markings that change significantly in location and shape over time. That’s because the red planet’s winds move dark-colored sand around the planet’s surface or sweep away brighter-colored dust.
Dust storms are so huge on Mars that at times, they extend three miles above the planet’s surface, covering all but the highest mountains.
Mars’ two moons, Deimos (pictured above) and Phobos, are so small and close to Mars that they aren’t visible from some parts of the Martian surface.
Though we call Mars the “red planet” because it looks that way from Earth, from a closer view its surface actually is multi-hued, with colors that include gold, brown, tan, green, and others.
Craters from meteor and asteroid strikes last longer on Mars than they do on Earth, because there is so little erosion.
Mars has the deepest, longest valley in the solar system. Valles Marineris stretches for nearly 2,500 miles, about the distance between Philadelphia and San Diego on Earth.
Though Mars is much smaller than Earth, its surface has far greater extremes in elevation than our planet does. The difference between the highest to the lowest point on the red planet is 18 miles, compared to 12.4 on Earth.
Though Mars is much smaller than Earth—its volume is just 15 percent of our planet—they have about the same land mass. That’s because two-thirds of the Earth’s surface is covered with water, and Mars doesn’t have any oceans, rivers or lakes.