Olympus Mons, the tallest volcano in the solar system, rises more than 75,000 feet from the Martian surface.
Although Earth and Mars may appear at first glance to be very different, closer inspection reveals a number of important similarities in structure, atmosphere and the natural forces that shape their landforms. Because of these similarities, scientists are studying Mars to find out what light it can shed on Earth's past and future.
Atmospheric Composition
Earth and Mars both have atmospheres consisting of oxygen, carbon dioxide and nitrogen. However, the concentrations of each gas are very different; for instance, carbon dioxide makes up roughly 95 percent of Mars' atmosphere, and almost .04 percent of Earth's. As such, Mars' atmosphere resembles that of Earth approximately 1 billion years ago. According to NASA scientists, it may be possible to "terraform" the Martian atmosphere to produce earthlike conditions.
Seasons and Days
Earth and Mars each have four distinct seasons, due to their similar tilt (Earth has a tilt of 23.4 degrees, while Mars has a tilt of 25.2 degrees). The length of a day is also similar on both planets: A Martian day lasts 24 hours and 39 minutes.
Magnetic Fields
Evidence indicates that early in its history, Mars had an active magnetic field. This field would have shielded Mars from cosmic radiation, and may even have enabled it to have a relatively earthlike environment. Furthermore, it appears that Mars' magnetic field reversed periodically, just as Earth's does.
Polar Ice Caps
Like Earth, Mars has large polar ice caps, the size of which varies by season. Mars' northern ice cap consists primarily of water, while the southern cap is a mixture of water and carbon dioxide.
Planetary Structure
Earth and Mars have similar geological structures. Both planets feature hard crusts and dense iron cores, and they also contain the same elements (though in different amounts). Although Earth is larger than Mars, they both have approximately 92,000,000 square miles of landmass. In other words, the total surface area of Mars is roughly equivalent to the surface area of Earth's continents.
Tectonics
Tectonic forces may have played an important role in shaping Mars during its first 500 million years. While Mars' southern hemisphere appears untouched by major tectonic events, its northern hemisphere comprises much younger rocks. Scientists are still studying and debating the exact nature of the tectonic forces at work on Mars.
Volcanism
Mars has several enormous shield volcanoes. These volcanoes are similar to Hawaiian volcanoes, in that they produce basaltic lava, but are much larger. Mars shows evidence of volcanic activity as recent as a few million years ago, and magma flows under the planet's surface still appear to be shaping its surface features.
Weathering
Although Mars' atmosphere is much thinner than Earth's, wind erosion appears to be a major force in shaping the planet's surface features. Atmospheric circulation is strong enough to create massive dust storms, which scour and erode Martian soil and rock formations. The existence of large sand dunes, particularly around the poles, is one result of this process.
Water
Evidence on the surface of Mars indicates the planet once had freely flowing water like Earth. This evidence includes river valleys, lakebeds, glacial deposits and indications of massive floods. Much of the planet's water is now frozen in its polar ice caps; scientists are still trying to determine where the rest of it went, and why.
Tags: Earth Mars, carbon dioxide, Mars atmosphere, Although Earth, both have, magnetic field, million years
