Mars is a little over half the size of the Earth. Its diameter is 4,222 miles, which is 53 percent of Earth's diameter. The planet's mass is also small, at about 10 percent of Earth's total. More » Science Astronomy Planets

A year on Mars is the equivalent of 687 Earth days or almost two years on Earth. The length of a year is determined by the amount of time it takes for a planet to make one complete orbit around the sun. More »

Mars revolves around the Sun once every 687 Earth days, or 1.88 Earth years. It revolves around the Sun at an average distance of 142 million miles, about 50 million miles farther out than the orbit of Earth. More » Science Astronomy Planets

Mars is similar to Earth in the fact that both planets have about the same amount of dry land surface. Both planets also have volcanoes and impact basins. More »

A person weighing 50kg (110lbs) on Earth would weigh 19kg (42 lbs) on Mars. This is because the gravitational force on Mars is only 38 percent that of the gravitational force on Earth. More »

The distance between Mars and Earth varies greatly depending on which point each planet is at in its orbit, according to Cornell University. The two planets' common reference point is the sun, which the Earth orbits at a... More » Science Astronomy Planets

Depending on the time of year and its position in the sky, Mars can be seen from Earth with the naked eye or in more detail with a small telescope. To the naked eye, Mars appears as a bright red star. With a telescope, o... More » Science Astronomy Planets