Marte

Marte is the fourth planet from the Sun and the second-smallest planet in the Solar System after Mercury. It has a diameter of about 6,779 kilometers and a mass roughly 10.7 percent that of Earth. The planet’s surface gravity is about 38 percent of Earth’s. Its atmosphere is thin and dry, with a mean surface pressure of about 6 to 8 millibars.

Its orbital period around the Sun is about 687 Earth days, and its day length is 24 hours 37 minutes. The axial tilt is about 25 degrees, producing seasons similar to those on Earth, though longer because of Marte’s longer year.

Marte features a long volcanic and tectonic history. Olympus Mons is the tallest volcano in the Solar System, about 22 kilometers high. Valles Marineris is a vast canyon system spanning thousands of kilometers. The planet has polar caps and signs of ancient flowing water.

The atmosphere is thin and dry, with dust storms that can envelop the planet. The surface shows a wide range of temperatures, from extremely cold nights to relatively warm days.

Marte has two natural satellites, Phobos and Deimos, small and irregularly shaped, likely captured asteroids.

Since the 1960s, numerous missions have explored Marte. Notable landers and rovers include Viking (1976), Pathfinder with Sojourner (1997), Spirit and Opportunity (2004), Curiosity (2012), InSight (2018), and Perseverance with Ingenuity (2020). Orbital missions such as Mars Odyssey and Mars Reconnaissance Orbiter have mapped Marte from space.

The planet is a key focus in questions about past habitability in the Solar System; evidence suggests that rivers and lakes may have existed billions of years ago, with subsurface ice remaining today.