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Learn about planets outside our solar system through Exoplanets and Alien Solar Systems by Tahir Yaqoob, Ph.D., a book in our online store book collection.

Does Mars have a core like the Earth? What are the similarities structurally between the Earth and Mars?

Due to a lack of seismic data for Mars, little is known about the structure of its interior. Estimates of the size of Mars' core range from 2200-4000 km in diameter and account for 6-21% of its mass. It is believed that Mars' core consists primarily of iron. However, its weak magnetic field suggests that the core is either small and solid, or larger and semi-solid or liquid.

Earth's core, on the other hand, is approximately 7000 km across and accounts for 32% of Earth's mass. The core consists of both iron and nickel and is structurally comprised of 2 parts: a solid inner core and a liquid outer core. Though the temperature of the inner core is sufficiently hot to melt iron (7400oF, or 4100oC), it remains solid because of the immense pressure exerted at the interior due to the Earth's weight.

Mars resembles Earth more than any of the other planets despite what appear to be significant differences. Mars is roughly half the diameter of Earth, but only about 1/10th its mass. Mars also has seasons like Earth though it's considerably colder overall (-63oF vs. 59oF on Earth). Unlike Earth, Mars does not have oceans and lakes, in fact there is very little water at all. And although Mars is one of the smallest terrestrial planets, it has some of the largest volcanic and tectonic features in the entire solar system. The largest of them all is a volcano named Olympus Mons which stands more than 16 miles (26km) high and 375 miles (600 km) across!

Submitted by Brian (Arizona, USA)
(September 8, 1997)

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF