Size of Mars

by Jerry Coffey on December 21, 2008

Mars Compared to Earth. Image credit: NASA/JPL

Mars Compared to Earth. Image credit: NASA/JPL

The size of Mars can not be given in one set of numbers. Scientists describe a planet by many factors. First there is radius, for Mars that is 3,389.5 km. Its circumference is 21,344 km. Next is volume, which is 1.63116 X 1011 km3. Last is Mar’s mass at 6.4169 x 1023 kg.

For comparison, Mars has 53% of the diameter of Earth. It has about 38% of the surface area of Earth. That sounds small, but that is equal to the total dry land here on Earth. The volume of Mars is equal to 15% of Earth’s and the Red Planet’s mass is 11% of Earth’s. As you can see, Mars is a small world, the second smallest in the Solar System.

Despite its small size, Mars has many interesting features that would seem larger than life. Olympus Mons is the tallest mountain in the Solar System and Valles Marineris is the deepest valley. Mars is home to hundreds of thousands of impact craters. Northern Polar Basin-Borealis Basin is largest at 10,500 km and Hellas Basin at 2,100 km is the third largest.

In addition to the extremes in topography, Mars is a world of weather extremes. Overall, it is a very cold world with an average surface temperature of about -47°C. During the summer, near the equator the temperatures can reach nearly 20°C during the day, but drop to -90°C at night. That 110° change in temperature can drive winds that reach tornado speeds. Once these winds start, they pick up the iron oxide dust that covers the planet, turning into a dust storm. There have been dust storms on Mars that have gotten large enough to engulf the entire planet for days at a time.

Scientists believe that Mars was a larger planet early in the history of the Solar System. The impact that created the Northern Polar Basin-Borealis Basin would have been large enough to eject a portion of the planet into space and beyond its gravitational pull; thus, the planet may have lost part of itself from the crash.

As you can see, the size of Mars is a minor fact amongst all of the interesting facts that you can discover about the Red Planet, but, hopefully, it is enough to get you to do more research.

Want information on other planets? Here’s an article about the size of Jupiter, and here’s one on the size of Saturn.

If you’d like more info on Mars, check out Hubblesite’s News Releases about Mars, and here’s a link to the NASA Mars Exploration home page.

We have recorded several podcasts just about Mars. Including Episode 52: Mars and Episode 92: Missions to Mars, Part 1.


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