Profile of the Planet Mars
The Mars rover Curiosity takes a self-portrait on the planet.
Named after the Roman god of war, the Red Planet still evokes wonder and mystery. Space missions to Mars constantly try to ascertain whether life, or even just liquid water, can exist on the planet. Before 1965, some speculated Mars had flowing water and vegetation, but the Mariner 4 spacecraft flew over and found that it had a rather barren landscape. Subsequent missions, however, have painted more complex pictures of the planet and have provided a rough profile of its atmosphere and its geology.
While Mars may have half the volume as Earth, it has only one-tenth of Earth’s mass. With a radius of 3,389.5 kilometers (2,106.1 miles) and a circumference of 21,296.9 kilometers (13,233.3 miles), Mars is the second smallest planet in the solar system. Surface area on Mars is only about a quarter of Earth’s, yet the amount of dry land on the two planets is roughly equivalent.
Mars is about 1.5 times farther from the sun than Earth. At its semi-major axis, Mars travels 227,943,824 kilometers (141,637,725 miles) to complete its orbit around the sun in about 687 Earth days. During this orbit, Mars travels at an average of 86,677 kilometers per hour (53,858 miles per hour). Two potato-shaped moons, Phobos and Deimos, orbit Mars. Some scientists think they are actually asteroids captured by Mars’ gravitational field.
A day on Mars is 24.623 hours, close to Earth’s 23.934 hours. Temperatures range from negative 87 to negative 5 degrees Celsius (negative 125 to 23 degrees Fahrenheit), reaching lows not experienced anywhere on Earth. The gravity on Mars is less than half as strong as Earth’s — a 45-kilogram (100-pound) person on Earth would weigh 17 kilograms (38 pounds) on Mars. If you were on Mars, you would experience similar weather seasons to Earth, but the seasons last longer. Mars also has polar icecaps that change with the seasons, active volcanoes and changing plate tectonics.
Public interest on Mars was piqued when scientists first found evidence the planet may have had water at one time. The atmosphere of the planet, however, is too thin to permit permanent liquid water. Past missions to Mars have found what could be remnants of floods from 3.5 billion years ago, but the large volumes of water are long gone. Scientists are now focusing their attentions to the clouds and soils to inspect for traces of water.