(CNN) — Hundreds of basketball-size space rocks slam into Mars each year, leaving behind impact craters and causing rumblings across the red planet, according to new research. Mission planners could ...

Determining the size of an Earth-size exoplanet by the amount of starlight it blocks hundreds of light-years away once was the realm of science fiction. Measuring the mass of such a small planet based ...

Earth and Mars in comparison. Mars has only about 10.7 percent of earth's mass but is roughly half its radius. Mars remains a true puzzle, but not for the reasons most people would think. Sure, ...

We know of Mars as the red planet, for its surface and atmosphere is caked in endless swirling dust of rusted iron, the rusting action provided by the always-eager oxygen. But this was not always so.

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