Mars is the fourth planet from the Sun, and it’s the second smallest in the Solar system after Mercury. Its name comes from Mars, the Roman god of war, but it is also often called “the Red Planet”. The reddish color of Mars is visible even to the naked eye, and this is because of the iron oxide ubiquitous on the surface of Mars. The planet has been known to mankind since ancient times, but over the last one hundred years, Mars has driven our imagination to the most extreme scenarios. But, is Mars really an interesting planet? Let’s see below everything that classifies as “fun fact Mars”.
Mars in numbers
Mars has a radius of 3390 km, it has a mass of 6.42×1024 kg (10.7% of Earth’s mass), and a mean density of 3.94 g/cm3. All these correspond to a gravity acceleration 3.72m/s2 (9.81 ~ m/s2 on Earth).
The planet is 227,939,200 km away from the Sun, and one year on Mars is equal to 687 days. The planet needs 24 hours, 39 minutes, and 35.2 seconds to rotate around its axis. The Martian day is known as “sol” (this is an actual term, and it was not made up in the Martian movie).
Mars has an axial tilt of 25.19°, so if you are on Mars, you will experience four seasons, just like Earth. The mean temperature on Mars is -63°C (-82°F), while the temperature can range between -143°C (-226°F), to 35°C (95°F).
Structure and atmosphere
Mars is a terrestrial (i.e., rocky) planet like Earth. This means it has an Earth-like structure, having a core, a mantle, and a crust.
The current models for the interior structure of the planet imply a core with a radius around 1800 km. The core consists primarily of iron and nickel, and a significant amount of sulfur (17%), and its abundance in lighter elements is two times higher than Earth’s core.
The core of Mars is surrounded by a silicate mantle responsible for the formation of many tectonic and volcanic features, but it seems to be dormant.
Mars has a crust with an average thickness of 50 km, but the thickness of the crust can have a maximum thickness of 125 km (Earth’s crust is on average 40 thick). The most abundant elements in the crust of Mars are silicon, oxygen, iron, magnesium, aluminum, calcium, and potassium.
The red planet has a very thin atmosphere (0.6% of Earth’s) composed mostly of carbon dioxide (~96%), argon (~2%), nitrogen (~2%), with traces of oxygen, water vapor, and carbon monoxide.
The tallest mountain and volcano in the Solar system is on Mars – Olympus Mons (Mount Olympus) is an extinct shield volcano in the Tharsis region on Mars. It is often called the tallest mountain in the Solar system with an altitude of nearly 22 km (A mountain structure on the asteroid Vesta has been measured at an altitude of 22 km). The volcano and the associated terrain are approximately 550 km across.
Mars has a canyon that dwarfs Grand Canyon – Perhaps the most spectacular feature on the surface of Mars is Valles Marineris (Mariner Valleys). It was discovered by the Mariner 9 in the early 70s. It is 4000 km long, 200 km wide, and it has a depth of 7 km. Unlike structures on Earth like the Grand Canyon, which were formed from water flow, Valles Marineris was formed because of the bulging of the surrounding region known as Tharsis area. Eventually, part of the crust collapsed, forming Valles Marineris.
Mars has the strongest dust storms – Dust storms on Mars can reach speeds over 160 km/h. What makes them extraordinary, is the fact that they can vary from a storm over a small area of the planet, to immense storms that can cover the entire planet. They are more prominent when Mars gets closer to the Sun, and they can increase the temperature of the planet.
Mars has ice polar caps just like Earth – Just like Earth Mars has two ice polar caps. The Northern cap (~ 1100 km across) is mostly iced water, while the southern cap is much smaller (~ 400 km), and it is composed of carbon dioxide ice. During winter, both get seasonal coatings of carbon dioxide ice, meaning that their size can increase.
There are new craters on Mars – NASA’s Mars Reconnaissance Orbiter has discovered recent impact craters on Mars. These impact craters were formed between 2008 and 2014. The craters resulted from a single meteoroid that broke up upon its entry on the atmosphere of Mars, and fragmented into two big larger mass objects and several smaller.
There are Marsquakes – Only within 2019, NASA’s InSinght mission recorded 450 Marsquakes and related events.
Satellites of Mars
Mars has two small natural satellites Phobos (diameter of 22 km) and Deimos (diameter of 12 km). Both have irregular shapes and orbit close to the planet. The origin of the Martian moons is uncertain, but the most accepted model suggests that Phobos and Deimos were asteroids captured by Mars’ gravity. Their names come from the Greek mythology, where Phobos (fear) and Deimos (terror), are the two sons of Ares, the god of war.
The distance between Mars and Phobos is just shy of 6,000 km. Phobos orbits around its host planet faster than Mars rotates around its axis in an equatorial orbit. So if you are in Mars at latitudes below 70°, you will see Phobos crossing the sky twice a day. So make sure you will not go near the poles, because you will not be able to observe Phobos.
So assume that you are still near the Martian equator. You will have the chance to observe regular transits of Phobos across the Sun. Deimos orbits Mars at a distance of 25000 km from Mars, thus because of its small size its transits are not that spectacular as Phobos’.
The gravitational effect of Mars on Phobos seems to be too strong for Phobos to handle. The satellite is gradually decreasing by two meters every 100 years. Thus, in around 50 million years, Phobos will be destroyed.
Exploration of Mars
Since the beginning of the space exploration era, Mars has been the target of every space program. Below you may find the landmark missions on Mars, together with the upcoming.
The first mission to Mars was launched on the 10th of October 1960, but the Soviet probe 1M No.1 was a failure. Note that during the 60s the rates of successful and failed missions were almost identical.
The first successful mission to Mars was the American Mariner-4, which flew by Mars on the 15th of July 1965.
The first soft landing on Mars happened on the 2nd of December 1971, when the Soviet Mars 3 lander transmitted the first-ever image from the surface of the planet.
The first successful orbiter on Mars was Mariner 9, when it entered into orbit around Mars, on the 14th of November 1971.
Mars during the 70s was really an American thing, with the two Viking landers, landing on Mars on the 20th of July 1976, and the 3rd of September 1976 respectively.
One of the most memorable dates on space exploration was the 4th of December 1998, when the Pathfinder probe landed on Mars, and the Sojourner rover (the first rover on another planet). returned the first images and data back to Earth.
Since then, NASA was really successful in sending rovers (Spirit, Opportunity, and Curiosity), and landers into Mars (Phoenix and InSight).
Although, all missions have shown that there is no life on Mars, and that its soil is toxic, the exploration of the planet is still going on. This coming July, three missions are programmed to visit Mars. These are NASA’s Mars 2020 (rover and helicopter), China’s Tianwen-1 (orbiter, lander, and rover), and Hope Mars from the United Arab Emirates (orbiter). Finally, in 2022 a combined mission from the EU and Russia is planned (ExoMars with a lander and rover) and the Japanese Mars Terahertz Microsatellite (orbiter and lander). So just stay tuned for even more surprises from Mars.