Mars

Mars is the fourth planet from the Sun. It is called the "Red Planet" because it looks orange-red. Mars is a rocky planet with a thin air that is mostly carbon dioxide. The temperature on Mars is very cold, from -153 to 20 degrees Celsius. It has very little air pressure compared to Earth. Even though it is harsh, Mars has some water in the ground, in the air as frost, and in big ice caps at its poles.

The surface of Mars is covered in fine dust. The north part of Mars is mostly flat land. The south part has many craters and high areas. Mars has huge volcanoes. The tallest is Olympus Mons. It also has a big canyon called Valles Marineris. Mars has two small moons, Phobos and Deimos. Like Earth, Mars has seasons because it tilts.

Mars formed about 4.5 billion years ago, about the same time as the other planets. Long ago, Mars may have had oceans and conditions that might have allowed life. Today, scientists are very interested in Mars. They want to know if life ever existed there, in the past or maybe now. Many spacecraft have visited Mars. We keep learning more about this amazing planet. Mars might be a place for humans to visit in the future.

Natural history

Main article: Geological history of Mars

Mars formed when our Solar System was created from bits of material around the Sun. Its place affected which elements were more common there, like chlorine and sulfur.

After the planets formed, Mars was hit many times by space rocks. Scientists think one very big impact shaped much of its northern area. Mars may have had rings long ago from an older, bigger moon. The planet's history has three main times: the Noachian, when its oldest surfaces and possible volcanoes formed; the Hesperian, when large lava plains appeared; and the Amazonian, which continues today and includes the growth of Olympus Mons, the largest volcano known in the solar system. Recent images show that Mars is still geologically active, with lava flows and water movement happening millions of years ago.

Physical characteristics

Main articles: Geology of Mars and Composition of Mars

Mars is smaller than Earth, about half its size. It looks like a desert from space. The red color comes from iron oxide, a kind of rust, on its surface. Mars has a thin atmosphere, mostly made of carbon dioxide.

Like Earth, Mars has layers inside. It has a core of iron and nickel, with rock layers around it. The surface is covered in basalt, a type of rock. The soil has nutrients for plants but also chemicals that could harm humans. Mars also has areas where the ground shifts, making streaks that change over time.

Geography and features

Main article: Geography of Mars

Further information: Areoid

See also: Category:Surface features of Mars

Mars is called the "Red Planet" because of its color. It has many interesting shapes and marks on its surface. People long ago, like Johann Heinrich von Mädler and Wilhelm Beer, were the first to watch Mars through telescopes and make maps of it. They made the first map of Mars in 1840 after many years of looking at it.

Places on Mars have different names. Some names come from old stories, while others are named after scientists, towns, or words that mean “Mars” or “star” in many languages. For example, some dark areas are named like seas, such as Mare Erythraeum and Aurorae Sinus. The north pole’s ice cap is called Planum Boreum, and the south pole’s is Planum Australe.

Mars has amazing mountains, valleys, and craters. The big volcano Olympus Mons is one of the tallest mountains we know of in our solar system. There are also huge valleys such as Valles Marineris, which is longer and deeper than the Grand Canyon on Earth. Mars has many craters from space rocks hitting it, and Hellas is one of the biggest. These features help us learn about Mars’s past and what it’s made of.

Atmosphere

Main article: Atmosphere of Mars

Mars has a very thin atmosphere, much thinner than Earth's. It is made mostly of carbon dioxide, with small amounts of argon and nitrogen. Because its atmosphere is so thin, temperatures on Mars can change a lot. Mars also has big dust storms that can cover the whole planet.

Mars has seasons like Earth, but they are different because Mars's orbit around the Sun is more stretched out. This means that the southern hemisphere has hotter summers and colder winters than the northern hemisphere.

Hydrology

Main article: Water on Mars

See also: Groundwater on Mars

Mars has a lot of water, but most of it is frozen ice covered in dust at the poles. If melted, the ice could cover the whole planet in water.

Liquid water can't stay on Mars' surface because the air is too thin. Mars has clouds made of water ice, and sometimes it snows or frosts, often mixed with dry ice. Long ago, Mars probably had rivers and lakes. We can see old riverbeds and valleys that look like they were carved by flowing water. There are also places that look like they were once underwater. Scientists have found minerals on Mars that usually form where there is water. This supports the idea that Mars once had more water than it does today.

Orbital motion

Main article: Orbit of Mars

See also: Timekeeping on Mars

Mars is the fourth planet from the Sun. It travels around the Sun in an oval-shaped path called an orbit. Mars is about 230 million kilometers from the Sun on average. It takes 687 Earth days to finish one orbit.

A day on Mars, called a sol, is a little longer than an Earth day—about 24 hours and 39 minutes. Mars tilts on its axis like Earth, so it has seasons. These seasons last almost twice as long as Earth's seasons.

Mars sometimes comes very close to Earth about every 780 days. When this happens, Mars looks brighter and can be seen more clearly through telescopes. The distance between Mars and Earth changes a lot because both planets have oval orbits. Sometimes they are very far apart and sometimes much closer.

Moons

Main articles: Moons of Mars, Phobos (moon), and Deimos (moon)

Mars has two small moons named Phobos and Deimos. Phobos is about 22 kilometers wide, and Deimos is about 12 kilometers wide. They were found in 1877 by a scientist named Asaph Hall and were named after characters from Greek mythology.

From Mars, these moons move in special ways across the sky. Phobos rises in the west and sets in the east, and it moves quickly. Scientists think that in about 50 million years, Phobos might get close enough to Mars to crash into the planet or break apart.

Human observations and exploration

Main articles: Exploration of Mars and History of Mars observation

People have watched Mars for thousands of years. Ancient groups like the Sumerians and Egyptian astronomers saw Mars moving in the night sky. They named it after gods and tracked its path.

In the 1600s, astronomers like Johannes Kepler and Galileo Galilei used new tools to study Mars. They found that Mars moves in an oval path around the Sun, not a perfect circle.

Later, people thought they saw straight lines on Mars called "canals". But better telescopes showed these were just tricks of the light. In the 1960s, spacecraft started visiting Mars. These missions gave us close-up pictures and data, showing that Mars is a dry, rocky world with a thin atmosphere.

Today, many spacecraft orbit Mars or drive on its surface, sending back important information. Scientists keep exploring Mars to learn more about its history and if it ever had conditions that could support life.

Habitability and habitation

Main article: Life on Mars

In the past, many thought Mars might support life because it looked like Earth. But studies showed Mars does not have much water or oxygen. Today, scientists think a planet needs liquid water to possibly support life. Mars sometimes gets close enough to the Sun for this to happen, but its thin air means water can't stay around for long.

Mars has many challenges for life. It doesn't hold heat well, it has no shield to protect it from the Sun's wind, and its air is too thin to keep water liquid. Mars is also mostly quiet, meaning it doesn't change its materials like Earth does. While there is evidence Mars was more friendly for life in the past, we still don't know if any living things ever existed there. Scientists keep looking for clues that might tell us more about the planet's history.

In culture

See also: Planets in astrology § Mars

Mars is named after the Roman god of war, though ancient astronomers also linked it to Hercules. Because of its red color, Mars has often been tied to ideas about war and battle throughout history.

People have imagined life on Mars for a long time, especially in books and movies. Early stories, like H. G. Wells's The War of the Worlds, featured Martians traveling to Earth. Later, fun characters like Marvin the Martian from the Looney Tunes cartoons added a humorous touch. Even today, Mars continues to inspire stories and imagination.