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This image shows the Earth and Mars

An Overview of the History of Mars

The terrestrial planets formed by accretion of rocky material and volatiles out of the primitive solar nebula. As they finished forming, about 4 Billion Years ago, the surface continued to be bombarded by the remanent of planetary material available nearby. This period is called the Period of Late, Heavy Bombardment. During this time, there was probably abundant water on the surface of Mars, and under ground. There was probably volcanic activity as well as plate tectonics. From the Period of Late, Heavy Bombardment forward, this is probably what happened to Mars:

The changes in climate probably persist to the present day, but the rest of the history of Mars was finished 3.5 Billion Years ago.

The reasons these things happened to Mars, and not to the Earth or Venus has to do with the small size of Mars, and the fact that Mars is farther from the sun that either the Earth or Venus. Some scientists call this the "Goldilocks" phenomenon.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA