Mars is the fourth planet from the Sun in the solar system. It is named after Mars, the god of war in Roman mythology because
of its red color as viewed in the night sky. This feature also earned it the name of "the Red Planet." Mars has two moons (Phobos and Deimos) which are both small and oddly-shaped, possibly being captured asteroids. The Chinese, Korean, and Japanese cultures refer to the planet as the Fire Star, based on the Five Elements. Mars has certainly been seen by skygazers since prehistoric times. It was known by the Egyptians as "Her Deschel" or "the Red One." Among the Babylonians Mars was known as "Nirgal" or "the Star of Death". The Romans were the ones to give Mars its modern name, after the God of War. Mars has always fascinated people. Its red, fiery appearance is caused by iron oxide (rust) on its surface. Mars has only a quarter the surface area of the Earth and only one-tenth the mass (though its surface area is approximately equal to that of the Earth's dry land because Mars lacks oceans).
The solar day (or "sol") on Mars is almost the same length as it is on Earth: 24 hours, 39 minutes, and 35.244 seconds. Mars'
atmosphere is thin: the air pressure on the surface is only 750 ascals, about 0.75
percent of the average on Earth. However, the scale height of the atmosphere is about 11 km, somewhat higher than Earth's 6 km. The atmosphere on Mars is 95 percent carbon dioxide, 3 percent nitrogen, 1.6 percent argon, and traces of oxygen and water. In 2003, methane was also discovered in the atmosphere by Earth-based telescopes, and possibly confirmed in March 2004 by the Mars Express Orbiter, present measurements state an average methane concentration of about 11±4 ppb by volume. The thin atmosphere cannot hold heat and is the cause of the lower temperatures on Mars (20 degrees Celsius or 68 degrees Fahrenheit is about as hot as it gets).