The closest planet of Earth

Of the six outer planets, Mars, commonly called the Red Planet is the closest to Earth. Mars, 4200 miles in diameter and 55% of the size of Earth is 334,600,000 miles from Earth and 141,000,000 miles from the Sun. It takes this planet along with its two moons, Phobos and Deimos 183 years to circle the Sun, compared to 365 days for the Earth.

For many years, Mars had been thought of as the planet with the man-made canals, supposedly discovered by an Italian astronomer, Schiaparelli, in 1877. With the United States spacecraft Viking I's landing on Mars in 1976 the man-made canal theory was proven to be only a myth.
After landing on the soil of Mars, Viking I performed many scientific experiments and took numerous pictures. The pictures showed that the red color of the planet is due to the reddish, rocky Martian soil. No biological life was found, though it had been speculated by many scientists. The Viking I also monitored many weather changes including violent dust storms. Some water vapor, polar ice and permafrost (frost below the surface) were found, indicating that at one time there were significant quantities of water on this distant planet. Evidence collected by the spacecraft shows some present volcanic actions, though the volcanoes are believed to be dormant, if not extinct.