Mars, the fourth planet from the Sun and the second-smallest in the solar system, is a reddish, rocky world. It’s named for the Roman god of war and is one of the most explored planets in the solar system.
Its surface features suggest that water once flowed across the planet’s surface. However, the planet’s thin atmosphere has made it difficult for liquid water to exist on the surface for long periods of time.
Earth’s Moon
The Moon is Earth’s natural satellite and the only planet in our solar system whose surface is visible to the naked eye. Since astronauts first walked on the Moon in 1969, scientists have learned a great deal about its history and geology.
Its surface is a unique mixture of different types of rock and minerals, but there are many similarities to Earth’s landscape. These include mountains, valleys and plains. The landscape changes as plate tectonics build new features and erosion destroys them.
Scientists believe that the Moon formed from a giant impact between Earth and another planet late in its formation. This collision occurred around 4.5 billion years ago and left behind debris that formed into the Moon’s orbit.
There are several theories for how this happened. Some suggest that the Moon was a wandering body that was captured by Earth’s gravity, while others believe that it was formed along with Earth as part of its formation.
Some of these theories are based on a large number of observations, while others are based on computer simulations and modeling. The most popular theory is the giant-impact model, which proposes that Earth collided with another planet about the size of Mars about 4.5 billion years ago.
This massive impact would have caused the mantle of Theia to coalesce with Earth’s core and vaporized its material. The debris would then have accumulated in a disk, from which the Moon accreted to form.
During the collision, the two planets were moving at very close speeds. These forces combined to generate a powerful gravitational force that forced the ejecta of both bodies outwards from their original positions. This collision created the craters that we see today on the Moon’s surface.
The Moon is made of a combination of oxygen, silicon, magnesium, iron, calcium, aluminum and a small amount of other elements. It has a very thin atmosphere, which moderates the temperature of its surface.
The surface of the Moon is constantly being affected by weathering and erosion, which makes it different from Earth’s surface. But that doesn’t mean it doesn’t have interesting features. One of the most striking is the bowl-shaped craters that are created by meteorite impacts.
Mars’ Moon Phobos
Phobos is the largest of Mars’ two moons. It is 17 miles (27 kilometers) across and orbits the planet three times a day, taking about 30 hours to complete an orbit. It is also the closest of the two, being only 5826 miles (9380 km) from the Red Planet.
The moon is incredibly irregular, looking more like an asteroid than a moon. Its surface is cratered, with one huge crater named Stickney that’s six miles wide. Other craters include Hall and Roche.
Unlike Earth’s Moon, which is round and has a mean diameter of about 14.2 miles (22.2 km), the irregular shape of Phobos means it will never be able to form a spherical orbit around Mars. As a result, it is slowly being drawn in by Mars’ gravity, so that within 50 million years, it will either crash into the planet or break up into a ring.
Researchers are hoping to find out more about the origin of these moons, which might help explain how they formed and what they are made of. A probe called MMX, which has been planned by Japan’s space agency, will try to send a rover down to the surface of Phobos to gather samples and analyze them.
According to a new study, Phobos shows signs that it was gouged apart by the extreme gravitational forces exerted by the Red Planet. The unusual grooves covering the surface, which were previously thought to be scars from an ancient asteroid impact, are actually dust-filled canyons that have grown wider as the moon gets stretched out by the strong gravity of Mars.
The research, published in the journal Nature, is based on data from NASA’s Mars Global Surveyor, which measured the surface of the moon and found a dust layer that was at least one metre thick. The team also analyzed radargrams sent by the spacecraft MARSIS.
The study suggests that the rocky moon may have originated from a D-type asteroid captured by Mars’ gravity. Or it could have been formed from fragments of a larger moon that crashed into Mars.
Mars’ Volcanoes
Mars has a huge amount of volcanic activity. Large lava flows, colossal shield volcanoes and individual eruptions that are more than 600 miles long are common on the planet. Some of these giant volcanoes are more than 100 times bigger than Mauna Loa in Hawaii, the largest shield volcano on Earth.
The biggest Martian volcanoes are located in the Tharsis region and Elysium province. They are similar to shield volcanoes found on Earth, with shallow-sloping flanks and summit calderas. However, the lava on Mars tends to flow in large rivers that are much longer than those on Earth.
Volcanic activity on Mars is believed to be driven by mantle plumes. These plumes are thought to be caused by heat escaping from the planet’s mantle, which is thinner than its Earth-like counterpart.
These plumes erode the surface and send up the plume’s rock and gas. This gas, if it is heated enough to melt the surface, can cause an explosion. The explosive eruption is called a pyroclastic event.
Scientists think this type of eruption is more likely to happen on smaller celestial bodies, like Mars. Smaller bodies tend to cool off faster than larger ones, so they lose their internal energy more quickly.
While most volcanic activity on Mars occurred between 3 and 4 billion years ago, a few small eruptions have occurred recently. This is one of the reasons that scientists have a hard time determining whether Mars was once habitable.
But a new study suggests that the Red Planet may have been habitable more recently than previously thought. This is because of a recent volcanic eruption that happened only 6 miles away from the youngest large impact crater on Mars.
This crater, named Zunil, is 6 miles wide and has a very young age of about 50,000 years. It is also right near the youngest seismic hot spot on the planet.
The discovery of the young volcanic eruption is significant because it could help explain why other studies have shown that the planet’s interior has been quiet for a while. It’s thought that the interior of the planet hasn’t been behaving because it’s too cold for liquid water to exist underneath the surface.
Mars’ Atmosphere
The Martian atmosphere is thinner than Earth’s and consists mostly of carbon dioxide. In addition, oxidized dust particles kicked up from the surface of Mars fill the atmosphere turning it a rusty tan color.
The thin air on Mars also means that temperatures are much colder. The average temperature is about -81 degrees F, but it can get down to -170 degrees F at night.
There are many different features of the Martian weather system, including dust storms that can reach 160 km/h (100 mph) and occasional CO2 fog in canyons. Some of these storms are so big that they can cover the planet.
Mars has polar caps that wax and wane with the seasons. During winter, they freeze onto the surface to form large slabs of CO2 ice, called “dry ice.” These ice sheets are a good place to look for signs of past water.
These ice sheets disappear as the seasons change and temperatures rise. Scientists have observed this process from orbit with spacecraft, from the ground with rovers and landers, and from Earth with big telescopes.
One important feature of the Martian climate is the seasonal occurrence of polar hoods, broad hazes of clouds that form over Mars’s polar regions. These clouds may be made of both water and CO2 ice.
At low latitudes, Mars has an atmospheric circulation pattern based on Hadley cell motion, named for English astronomer George Hadley (1685-1768). In this pattern, heated air rises around the equator and flows north and south to 30 deg latitude, where it cools and sinks. The resulting air mass then flows back toward the equator at the surface.
During the summer months, the winds flow across the planet’s surface, blowing from west to east, and carrying dust and other materials. This is known as frontal storming. The storms tend to be less violent than terrestrial storms because the thinner atmosphere and lower pressures are responsible for causing them.
At higher latitudes, the prevailing flow is influenced by the varying heights of mountains and other natural landforms. At these higher altitudes, sharp frontal storms may be more common. However, they are less likely to be powerful because the thinner atmosphere and the lack of an ozone layer prevent them from producing as much energy.