Mars

Mars is the fourth planet from the sun. It is a terrestrial planet, because it is very similar to the Earth in terms of atmosphere and surface features.

How big is planet Mars?

Mars is 6,804.9 km or 0.533 Earths in diameter. That makes it a little more than half of Earth's diameter, so its volume is around 15% that of the Earth.

What is the surface of Mars like?

The surface of Mars is dry and dusty. The highlands of the southern hemisphere have more craters than the lower areas in the northern hemisphere. One of the craters is the huge Hellas Planitia. It is 2100 km across.

There is an area called the Tharsis Bulge that has four huge volcanos. These volcanos have not erupted for millions of years. The largest one is Olympus Mons. It is 27 km tall, making it the highest mountain in the solar system and much higher than Mount Everest on Earth. It is 540 km across, making it too big to see the whole thing from the surface of Mars.

Mars has a huge canyon called Valles Marineris that is much bigger than the Grand Canyon on Earth. It is 4000 km long, up to 7 km deep and up to 200 km wide. It it thought that Valles Marineris was made when the surface cracked when the Tharsis Bulge formed.

There are also two ice caps at the poles. They are made of carbon dioxide and water ices. The northern one is large and the southern one is small.

In some places, there are channels that look like they were made by water erosion. Mars may have once been a wet planet like Earth.

If you got in a spaceship and landed on the surface of Mars, you would notice that there is air and an atmosphere, but it is very thin. When you are standing at the bottom of Valles Marineris, there is almost the same air pressure as you would find on the top of the tallest mountain on Earth, Mount Everest. Even then, you would not want to breathe it because it has very little oxygen, and much more carbon dioxide than on the Earth. Carbon dioxide is the gas that you send out from your lungs when you are breathing. Even with these problems, someday people will travel to Mars and walk on its surface.

Is there life on Mars?

This is a question that many scientists have been asking for a very long time. When telescopes were first became powerful enough to study Mars in detail, the Italian astronomer Giovanni Schiaparelli spotted lines on the surface of Mars that he believed to be like rivers. Unfortunately this word in Italian, when translated into English was also the same word for canals, and that sparked the imaginations of many people to believe that there was not only living things on Mars, but an advanced civilization of people that built cities and structures that could be seen on the Earth, like the Great Wall of China is visible from space as the sign advanced tool making.

Popular fiction took advantage of this interest, and the notion of Martians invading the Earth is a common idea in stories like this. Perhaps the most famous story using this idea is the novel "The War of the Worlds", by H.G. Wells, which includes some scientific opinions of what astronomers thought might be on Mars when that book was written. This story has since been made into a movie on several occasions, theatrical stage productions, and even radio dramas.

Most astronomers and space scientists no longer believe that there is an advanced civilization on Mars. The question is now if anything, even small plants and animals ever lived on Mars in the past or are still living there. This question is still unanswered, but there have been some attempts to find out.

In 1976, robot spacecraft from Earth called Viking landers went to Mars to find out. When it landed, the pictures of Mars that came back to Earth made Mars look very much like a desert, with very little water. Some experiements that were done to Martian soil seemed to indicate there was no life on Mars, although one experiment did indicate that there might be something alive in the soil. Even that experiment, however, was not convincing.

Shortly after the Viking space missions, a rock was discovered in Antarctica that was believed to have come from Mars. When scientists examined the inside of that rock, they discovered that there might be an ancient fossil of some bacteria.

Another robotic spacecraft called Mars Observer has been orbiting Mars for several years now, and it has taken photos of riverbeds and other features on the surface that suggest that Mars had liquid water flowing on the surface. If this is true, it seems likely that at least some very simple form of life may have lived on Mars as well.

In spite of all the scientific research to search for life on Mars, the question still hasn't been completely answered, and this is something that is debated by scientists even today.

What are Mars moons like?

It is believed that these moons did not originally orbit Mars, but were instead a part of the Asteroid belt. When these pieces of the Solar System came close to Mars, they were captured by the gravity of Mars and went into relatively stable orbits around Mars. Like the Earth's moon, these moons are in a tidal lock, always keeping the same face towards Mars while they are in orbit.

Mars has two natural satellites:

Phobos

In Roman mythology both Phobos and Deimos were the sons of the Roman god Mars. Phobos means "fear" or "fright". Phobos also orbits closer to Mars than any other moon to any other major planet in the solar system. In a few million years Phobos will eventually crash into the surface of Mars due to orbital decay, where it goes closer to the surface of Mars every year.

Deimos

Deimos means "panic" or "dread" as the son of Mars. Deimos is one of the smallest moons of any planet in the Solar System (so far).

How long is a day on Mars?

One day on Mars is only a little longer than an Earth day at 1.025 Earth days. A year is 1 Earth year and 322 Earth days long.

What is Mars made of?

It is thought that Mars has an iron and sulfur core and a mantle and crust made of silicate.

How much would Mars's gravity pull on me?

If you were on Mars, it would pull you down with a force about two fifths as strong as the force of Earth's gravity. This would make somebody living on the surface of Mars to experience something significantly different. You could lift objects that weigh almost three times as much compared to similar objects here on the Earth. You could jump up almost three time higher, but it would take much more time in order to fall to the ground from the same height.

Even though it appears as though you would be like a comic-book hero on Mars, you would still have to worry about the mass of an object. A large object that is moving forward would still crush you if you got in its way, just like it would be a problem here on the Earth, and a bullet from a gun would do just as much damage on Mars as it does on the Earth.

Who is Mars named after?

Due to its red appearence in the sky, Mars is named after the Roman god of war.