Mars is a rocky planet that orbits our Sun, a star. Like Earth, it has clouds, winds, seasons, polar ice caps, volcanoes and canyons.
It also has two moons: Phobos, an inner moon, and Deimos, an outer one. Both are pockmarked with craters from meteor impacts.
The Red Planet
Mars is the next planet out from Earth in our solar system. It is about one-third the size of our home world and has about one-third of the gravity. This means that when a rock is dropped on the planet, it falls slower than on Earth.
Mars has many surface features, including volcanoes like Olympus Mons and canyons like Valles Marineris. These areas were probably created by the flow of water across the planet’s surface in past eras.
Despite these unusual features, Mars’ atmosphere is cold enough that liquid water cannot exist on its surface for long periods of time. In addition, the thin atmosphere makes it difficult for any life forms to survive on Mars.
The Red Planet also has a large moon, Phobos, which slowly gets closer to the planet at a rate of about 2 cm per year. It will either crash into Mars or disintegrate to form a ring around it within 50 million years.
Since the 1960s, NASA and other space agencies have sent numerous spacecraft to Mars. The Viking 1 lander successfully touched down in 1976, followed by its twin Viking 2.
Some of the most interesting features on the surface of Mars are Olympus Mons, which is the largest volcano and highest-known mountain in the Solar System; and Valles Marineris, a series of deep canyons that run east-west for about 2,500 miles (4,000 km). These features were created by the flow of water across the planet’s surfaces in past eras.
Another fascinating feature of the Martian surface is the dust storms that are common there. These windstorms lift rust-colored dust high into the Martian air and can cover the entire planet! Tiny dust storms can look like tornadoes, while large ones can encircle the planet.
These windstorms are dangerous for robots on the Martian surface. Some of NASA’s robotic Mars rovers died in 2018 after they were engulfed in a dust storm that blocked sunlight from reaching their solar panels for weeks at a time.
For more information about Mars, visit the National Aeronautics and Space Administration website. There, you can find the NASA Explorer’s Club, an online resource that has everything from educational videos to articles about this mysterious planet. It’s a great resource for teachers and parents looking for ways to engage students in science, technology, engineering and mathematics.
The Moon
The Moon is a natural satellite of Earth, and it is also one of the largest moons in the solar system. It orbits Earth about a common centre of mass called the barycentre. It has a relatively large ratio of mass to its planet and exerts a strong gravitational influence on Earth.
The surface of the Moon is quite different from that of the Earth, and there are many features to explore. Its surface is full of craters, mountains and valleys that were formed by meteorite impacts over billions of years.
It is also known for having a very thin atmosphere, which contains helium, neon, methane, argon and carbon dioxide, as well as sodium and potassium. This gas is not present on the Earth, Venus or Mars and may be a result of evaporation from the Moon’s surface or meteor impact.
While it is still not possible to visit the Moon and study its surface, scientists have gathered a lot of information about its formation. It is thought that it formed from the debris of a large collision between a Mars-sized object and Earth about 4.5 billion years ago.
During its early history, the Moon was enveloped in a deep ocean of liquid rock, called a magma ocean. Over time, the ocean crystallized and less dense rocks accumulated on top, forming the crust of the Moon.
When the Moon was first formed, it probably had a large amount of oxygen in its crust. As the crust cooled, the oxygen was converted to heavier metals. The result was a small core that contained iron and other heavy elements.
The core is surrounded by a thick mantle that stretches over 1,000 kilometers (620 miles) across. This mantle is mainly made of iron and magnesium, with traces of sulfur and nitrogen.
The Earth-Moon system is tidally locked, meaning that each side of the Moon orbits about the same centre of mass, the barycentre. This tidal locking is caused by the pull of the Moon on the Earth and slows down both bodies’ rotational pace. This braking effect adds around 1.4 milliseconds of time to our day each century.
The Atmosphere
The Atmosphere of Mars is a complex system made up of carbon dioxide, nitrogen and water. It is a thin atmosphere with a density less than 1% of Earth’s, owing to its low surface gravity (compared to Earth).
The atmosphere on Mars is about 95% carbon dioxide, 3% nitrogen and 1.6% argon. It also contains traces of oxygen and water.
Atmospheric pressure on the surface ranges from a low of 30 Pa to over 1,155 Pa in Hellas Planitia and Olympus Mons. The mean surface pressure is 600 Pa.
As Mars approaches perihelion (closest point to the Sun), its air gets heated. This heat is transported around the planet by the Hadley cell pattern. The Hadley cells, named for English scientist George Hadley, feature rising, warmed air that flows northward and southward, primarily in the northern and southern hemispheres, but varies between latitudes.
This process is aided by the rotation of the planet and by surface landforms that direct airflow. The flow is a mix of updrafts and downdrafts, but in the northern hemisphere, it tends to be more updraft-dominated.
Another activity of the atmosphere is evaporation of water vapour. This occurs at the highest altitudes, ranging from 110 km to 130 km above the surface.
These vapors are mostly from surface sources, but some also come from the Martian soil. This is an important finding for scientists looking for signs of life.
However, these vapors are too weak to support biological activity. And, given the sensitivity of the environment to ultraviolet radiation from the Sun, it is unlikely that any organic molecules would have survived in these conditions.
The atmospheric inventory of trace gases makes up a small percentage of the overall atmosphere, but it is critical for understanding the planet’s internal processes. Trace gas data from the ExoMars mission will help scientists understand the history and current state of the planet’s atmosphere.
The atmosphere on Mars has undergone significant changes in its past. Evidence suggests that the planet’s early climate was much warmer and wetter than today. Some of this may be due to the evaporation of water from the surface, but it could also be due to the loss of a magnetosphere about 4 billion years ago. Without one, the solar wind can strip atoms from the atmosphere.
The Surface
The surface of Mars has many features that show signs of the planet’s watery past. It contains ancient river valley networks, deltas and lakebeds, as well as rocks and minerals on the surface that could only have formed in liquid water. Some of these features suggest that Mars experienced huge floods about 3.5 billion years ago.
The northern plains of Mars are among the flattest and smoothest areas in the solar system, potentially created by water that once flowed across the Martian surface. These northern plains are also lower than the southern, suggesting that the crust may be thinner in the north.
One of the most intriguing parts of the Martian landscape is a fragmented, furrowed escarpment in an area known as Nili Fossae (image above). This image from NASA’s Mars Reconnaissance Orbiter shows the region, which has been sculpted by erosion through ongoing wind, water and ice activity.
Another striking feature of the Martian surface is a series of large, high-rise volcanoes. The volcanoes, which are called craters, were formed from massive asteroid impacts that hit the planet during one to three billion years ago.
As the rover Curiosity has explored the surface of Mars, it has discovered organic compounds in sedimentary rock dating back to 3 billion years ago. These organic molecules are similar to the building blocks of life, and are thought to be evidence that there was, at some point, a habitable environment on Mars.
Despite its reputation as an arid planet, Mars is a very active world, with geological processes reworking the surface continuously and riven with subsurface canals. This reworking can produce a variety of different landforms, from volcanoes and canyons to dust storms and layers of ice at the poles.
A rocky planet, Mars has a core of iron and nickel with a silicate mantle made up of sulphur and other elements. As a result, the planet has an atmosphere that consists mainly of carbon dioxide and some small amount of nitrogen.
The atmosphere of Mars is much thinner than that of Earth, which makes it possible for water to exist on the planet’s surface, but it would be very difficult for it to last for any length of time. However, there are signs that water has once flowed on the planet’s surface, and scientists believe that water still exists in the form of frozen water-ice that is found at the polar regions. In addition to this, a region in the south called Ma’adim Vallis is believed to have been carved by flowing water long ago.