Mars is rightfully called the "Red Planet" because the prevalence of iron oxide really gives the surface a reddish look. It has a real surface with a thin atmosphere. It has craters like those on our Moon. And volcanoes, valleys, desserts, and polar ice caps, like those on Earth. Seasonal cycles are similar to those of Earth, because Mars has nearly the same degree of tilt as our planet. Mars' radius is approximately half the radius of the Earth. It is approximately half the size of Earth. In most other respects, it is very much not like the Earth. Although, the more these planets are studied, the more uniqueness of their own they show.
Mars has the highest known mountain in the Solar System, called Olympus Mons, which is a volcano. That mountain is 27 km high, so it is more than three times higher than our Mount Everest. The vast upland region Tharsis, where this mountain is located, is also home to several other large volcanoes.
Mars also has the largest known canyon in the Solar System, called Valles Marineris. This canyon has a length of 4,000 km and up to 7 km deep. It extends across one-fifth of the circumference of Mars. Its length is equivalent to the length of the entire Europe. Our Grand Canyon, by comparison, is only 446 km long and nearly 2 km deep. Another Martian Volcano, Ma'adim Vallis, is 700 km long, 20 km wide, and 2 km deep. The smooth Borealis Basin covers 40% of the planet.
Seven possible cave entrances have been discovered on the flanks of Arsia Mons volcano. Collectively, they are called the "Seven sisters". Individually, they are named after the names of loved ones of their discoverers. "Dena" is the only cave of the seven, whose depth was seen, at 130 m deep. The entrances to these caves have been measured to be between 100 m and 252 m wide. The caves are believed to be at least 73-96 m deep. But it is very likely that they go much deeper, as the light does not reach the floor of most caves.
The atsmophere of Mars is 95% carbon dioxide, 3% nitrogen, 1.6% argon. It also contains traces of oxygen and water. It is quite dusty, which would give the sky a yellow-brown color if you were to look up from the surface of Mars. Methane has also been detected in the atmosphere, which is believed to be produced from two regions on Mars. It is estimated that 270 tons of methane are produced on Mars in a year.
Water on Mars?
Prior to space visits to Mars, many scientists speculated the presence of entire streams or even seas of water on Martian surface, because it looked like seas from telescopes. When spacecraft arrived at Mars, they discovered those were just optical illusions. Samples taken by the rovers, however, have found water ice or chemical compounds containing water molecules in the soil. Radar data from Mars orbiting spacecraft also revealed what looks like large ice caps at the Martian poles and at mid-latitudes. Water ice has been claimed to exist in all parts of the Solar System. And that should be very well expected based on the Genesis account of creation, where the universe was created from water. Large reservoirs of water may have been existing on Mars in the past, but as to the amount and details, we just don't know, because we were not there to see it. There are extensive theories on the subject, but they are as speculative as the initial theories on water seas on Mars prior to visiting it.
Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These moons look like asteroids, but have circular orbits around the equator, like moons.
In our modern civilization, astronomers have determined permanent surface features on Mars since 1840. Because the surface of Mars has been studied so extensively, it is mapped just like our Earth or our Moon. The paler plains covered with dust and sand, which were believed to be 'continents' before, are given names that sound like Earth's land names (ex: Arabia Terra, Amazonic Planitia). The darker regions, once believed to be seas, are given names that sound like sea names. The northern polar ice cap is called Planum Boreum, while the southern cap is named Planum Australe. Craters larger than 60 km are named after deceased people who made a contribution into the study of Mars. Craters smaller than 60 km are named after towns and villages with a population of less than 100,000 people. Larger valleys are named after the translations of the word "mars" or "star" in different languages. Small valleys are named after Earth's rivers.
Mars is home of many craters that are believed to be sites of impacts with other space objects. The size, quantity, and times of these impacts is a very speculative matter, because, again, we haven't been there to see it. But Mars is very close to the asteroid belt. It also has a greater chance of beign struck by short-lived comets such as those that lie within the orbit of Jupiter. If the asteroid belt, is in fact, the remains of an exploded planet, that exposion event could account for the larger craters on Mars. There are not as much craters on Mars, however, when compared to the amount of craters on our Moon, because Mars has an atmosphere that would melt smaller meteorites before they reach the planet's surface.
Seasons of Mars are very much like on Earth, because of very similar planet tilts. But these seasons are twice as long as on Earth, because Mars is farther from the Sun than we are. Surface temperatures vary from -87 C during winters to -5 C during summers. Summer temperatures in the southern hemisphere can be up to 30 C warmer than during northern hemisphere's summer.
Mars is a planet of many dust storms. These storms can range from local storms over a small area, to a world-wide storm, that prevents the Sun from shining on the surface of the entire planet for some time. These global storms tend to occur when Mars is closest to the Sun, and have been known to raise the global temperature.
Give me a break! Although they do make nice science fiction movies.