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

Mars has two moons: Phobos and Deimos. Both moons are irregularly shaped and very small in size compared to the Earth’s moon. Phobos is the larger of the two, with an average radius of 6.9 miles; Deimos has an average ra... More »

The force of gravity on the planet Mars is only about 38 percent as strong as that on Earth. Surface gravity on Mars is much weaker than that of Earth due to the planet's small size and relatively low mass. 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 »

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 »

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

The average distance to Mars from Earth is 140,000,000 miles or 225,000,000 kilometers. However, this value varies because the Earth's orbit around the sun is smaller than Mars' orbit. More »