Mars, often called the Red Planet, has long captivated humanity. The planet holds many secrets, revealed gradually through robotic missions and telescopic observations. Exploring its intriguing characteristics helps us understand why Mars stands out among our solar system’s celestial bodies.
The Red Planet’s Rusty Hue
Mars’s striking red color, visible even from Earth, is its most iconic feature. This hue results from the widespread presence of iron oxide, commonly known as rust, in its soil and dust. Iron minerals in the Martian regolith react with water and oxygen, undergoing a process similar to how rust forms on Earth. Over vast stretches of time, this rusty material has been broken down into fine dust and spread across the planet by strong winds.
Recent research suggests that Mars’s red dust is primarily composed of ferrihydrite, a type of iron oxide that contains water. This indicates that the rusting process likely occurred early in Mars’s history when liquid water was more prevalent on its surface. The planet’s “red” nickname has been used for millennia, with ancient civilizations also associating its color with gods of war.
A Colossal Mountain in Our Solar System
Mars hosts Olympus Mons, a shield volcano that stands as the largest mountain in the entire solar system. Its summit reaches over 21.9 kilometers (13.6 miles) above the surrounding plains, making it approximately two and a half times taller than Earth’s Mount Everest. The base of this volcano spans about 600 kilometers, an area comparable to the size of a large country like Italy or the Philippines.
Olympus Mons achieved such a size due to several factors unique to Mars. The planet’s lower gravity, roughly 38% of Earth’s, allows structures to grow much taller without collapsing under their own weight. Mars lacks active plate tectonics, unlike Earth. On Earth, moving tectonic plates eventually carry volcanoes away from their underlying magma hotspots, leading to new volcanoes forming elsewhere. On Mars, the stationary crust allowed lava to continuously erupt from the same spot for hundreds of millions of years, building Olympus Mons into its record-breaking form.
Two Oddball Moons
Mars is orbited by two small, irregular moons named Phobos and Deimos, discovered by American astronomer Asaph Hall in 1877. These moons were named after the Greek mythological twin characters Phobos (Fear) and Deimos (Panic), who accompanied their father Ares, the Greek counterpart to the Roman god Mars. Phobos measures about 22.2 kilometers across, and Deimos is 12.6 kilometers.
Both moons have an irregular, “potato-shaped” appearance and are heavily cratered, reflecting their turbulent history. They are also very dark, appearing blacker than coal. Phobos orbits extremely close to Mars, completing an orbit about three times a day, while the more distant Deimos takes approximately 30 hours for each orbit. Scientists believe that Phobos and Deimos are captured asteroids, pulled into Mars’s orbit by its gravity long ago, rather than forming alongside the planet. Their composition, similar to carbonaceous asteroids, supports this theory.