Mars is one of the most explored bodies in our solar system, and it's the only planet where we've sent rovers to roam the landscape finding evidence that, billions of years ago, Mars was wetter and warmer with a thicker atmosphere.
Mars was named by the Romans for their god of war because its reddish colour was reminiscent of blood. The Egyptians called it "Her Desher," meaning "the red one." Even today, it is frequently called the "Red Planet" because iron minerals in the Martian dirt oxidize, or rust, causing the surface to look red.
Scientists don't expect to find living things currently thriving on Mars. Instead, they're looking for signs of life that existed long ago, when Mars was warmer and covered with water.
With a diameter of 6,794 kilometers (2,106 miles), Mars is about half the size of Earth. From an average distance of 228 million kilometers (142 million miles), Mars is 1.5 astronomical units away from the Sun. (One astronomical unit is the distance from the Sun to Earth.) From this distance, it takes sunlight 13 minutes to travel from the Sun to Mars.
As Mars orbits the Sun, it completes one rotation every 24.6 hours, which is very similar to one day on Earth (23.9 hours). Martian days are called sols – short for "solar day." A year on Mars lasts 669.6 sols, which is the same as 687 Earth days.
Mars' axis of rotation is 25 degrees very similar to Earth’s 23.4 degrees. Like Earth, Mars has distinct seasons, but they last longer than seasons here on Earth since Mars takes longer to orbit the Sun. And while here on Earth the seasons are evenly spread over the year, lasting 3 months, on Mars the seasons vary in length because of Mars' elliptical, egg-shaped orbit around the Sun. Spring in the northern hemisphere (autumn in the southern) is the longest season at 194 sols. Autumn in the northern hemisphere (spring in the southern) is the shortest at 142 days. Northern winter/southern summer is 154 sols, and northern summer/southern winter is 178 sols.
Scientists don't expect to find living things currently thriving on Mars. Instead, they're looking for signs of life that existed long ago, when Mars was warmer and covered with water.
With a diameter of 6,794 kilometers (2,106 miles), Mars is about half the size of Earth. From an average distance of 228 million kilometers (142 million miles), Mars is 1.5 astronomical units away from the Sun. (One astronomical unit is the distance from the Sun to Earth.) From this distance, it takes sunlight 13 minutes to travel from the Sun to Mars.
As Mars orbits the Sun, it completes one rotation every 24.6 hours, which is very similar to one day on Earth (23.9 hours). Martian days are called sols – short for "solar day." A year on Mars lasts 669.6 sols, which is the same as 687 Earth days.
Mars' axis of rotation is 25 degrees very similar to Earth’s 23.4 degrees. Like Earth, Mars has distinct seasons, but they last longer than seasons here on Earth since Mars takes longer to orbit the Sun. And while here on Earth the seasons are evenly spread over the year, lasting 3 months, on Mars the seasons vary in length because of Mars' elliptical, egg-shaped orbit around the Sun. Spring in the northern hemisphere (autumn in the southern) is the longest season at 194 sols. Autumn in the northern hemisphere (spring in the southern) is the shortest at 142 days. Northern winter/southern summer is 154 sols, and northern summer/southern winter is 178 sols.
Moons
Mars has two small moons, Phobos and Deimos, that may be captured asteroids. They're potato-shaped because they have too little mass for gravity to make them spherical.
The moons get their names from the horses that pulled the chariot of the Greek god of war, Ares.
Phobos, the innermost and larger moon, is heavily cratered, with deep grooves on its surface. It is slowly moving towards Mars and will crash into the planet or break apart in about 50 million years.
Deimos is about half as big as Phobos and orbits two and a half times farther away from Mars. Oddly-shaped Deimos is covered in loose dirt that often fills the craters on its surface, making it appear smoother than pockmarked Phobos.
Mars has two small moons, Phobos and Deimos, that may be captured asteroids. They're potato-shaped because they have too little mass for gravity to make them spherical.
The moons get their names from the horses that pulled the chariot of the Greek god of war, Ares.
Phobos, the innermost and larger moon, is heavily cratered, with deep grooves on its surface. It is slowly moving towards Mars and will crash into the planet or break apart in about 50 million years.
Deimos is about half as big as Phobos and orbits two and a half times farther away from Mars. Oddly-shaped Deimos is covered in loose dirt that often fills the craters on its surface, making it appear smoother than pockmarked Phobos.
Formation
When the solar system settled into its current layout about 4.5 billion years ago, Mars formed when gravity pulled swirling gas and dust in to become the fourth planet from the Sun. It has a central core, a rocky mantle, and a solid crust.
While Mars is about half the diameter of Earth, its surface has nearly the same area as Earth’s dry land. Its volcanoes, impact craters, crustal movement, and atmospheric conditions such as dust storms have altered the landscape of Mars over many years, creating some of the solar system's most interesting topographical features.
A large canyon system called Valles Marineris is long enough to stretch from California to New York – more than 4,800 kilometres (3,000 miles). This Martian canyon is 320 kilometers (200 miles) at its widest and 7 kilometers (4.3 miles) at its deepest. That's about 10 times the size of Earth's Grand Canyon.
Mars is home to the largest volcano in the solar system, Olympus Mons. It's three times taller than Earth's Mt. Everest with a base the size of the state of New Mexico.
There is water on Mars today, but the Martian atmosphere is too thin for liquid water to exist for long on the surface. Today, water on Mars is found in the form of water-ice just under the surface in the polar regions as well as in briny (salty) water, which seasonally flows down some hillsides and crater walls.
When the solar system settled into its current layout about 4.5 billion years ago, Mars formed when gravity pulled swirling gas and dust in to become the fourth planet from the Sun. It has a central core, a rocky mantle, and a solid crust.
While Mars is about half the diameter of Earth, its surface has nearly the same area as Earth’s dry land. Its volcanoes, impact craters, crustal movement, and atmospheric conditions such as dust storms have altered the landscape of Mars over many years, creating some of the solar system's most interesting topographical features.
A large canyon system called Valles Marineris is long enough to stretch from California to New York – more than 4,800 kilometres (3,000 miles). This Martian canyon is 320 kilometers (200 miles) at its widest and 7 kilometers (4.3 miles) at its deepest. That's about 10 times the size of Earth's Grand Canyon.
Mars is home to the largest volcano in the solar system, Olympus Mons. It's three times taller than Earth's Mt. Everest with a base the size of the state of New Mexico.
There is water on Mars today, but the Martian atmosphere is too thin for liquid water to exist for long on the surface. Today, water on Mars is found in the form of water-ice just under the surface in the polar regions as well as in briny (salty) water, which seasonally flows down some hillsides and crater walls.
Atmosphere
Mars has a thin atmosphere made up mostly of carbon dioxide, nitrogen, and argon gases.
The temperature on Mars can be as high as 70 degrees Fahrenheit (20 degrees Celsius) or as low as about -225 degrees Fahrenheit (-153 degrees Celsius). And because the atmosphere is so thin, heat from the Sun easily escapes this planet. If you were to stand on the surface of Mars on the equator at noon, it would feel like spring at your feet (75 degrees Fahrenheit or 24 degrees Celsius) and winter at your head (32 degrees Fahrenheit or 0 degrees Celsius).
Occasionally, winds on Mars are strong enough to create dust storms that cover much of the planet. After such storms, it can be months before all of the dust settles.
Mars has a thin atmosphere made up mostly of carbon dioxide, nitrogen, and argon gases.
The temperature on Mars can be as high as 70 degrees Fahrenheit (20 degrees Celsius) or as low as about -225 degrees Fahrenheit (-153 degrees Celsius). And because the atmosphere is so thin, heat from the Sun easily escapes this planet. If you were to stand on the surface of Mars on the equator at noon, it would feel like spring at your feet (75 degrees Fahrenheit or 24 degrees Celsius) and winter at your head (32 degrees Fahrenheit or 0 degrees Celsius).
Occasionally, winds on Mars are strong enough to create dust storms that cover much of the planet. After such storms, it can be months before all of the dust settles.