A giant gash slices across the surface of Mars. It’s a network of canyons and valleys that’s among the most impressive features in the solar system.
Valles Marineris consists of about a dozen major canyons. Together, they span about 2500 miles — equal to the width of the United States. Individual canyons are up to about 125 miles wide. Several of them merge in the middle of the system, where they form a basin that’s 375 miles wide and almost six miles deep.
Valles Marineris has a complicated history. The first canyons probably formed billions of years ago, when the planet was quite young. A nearby network of massive volcanoes got so heavy that it created cracks in the crust. The cracks then grew wider, creating long, deep canyons.
Over the eons, though, other processes have helped carve the canyons. That includes erosion by wind and water. In fact, water may have partially filled some of the canyons, creating lakes that deposited layers of sediments. Some of the water may have burst out of the eastern end of Marineris in massive floods, carving deep channels.
And today, landslides along the canyon walls help make the channels wider — making the Grand Canyon of Mars even more spectacular.
Look for Mars to the upper right of the crescent Moon this evening. The little planet looks like a bright orange star. And as a bonus, the planet Uranus is nearby, too, although you need binoculars to see it.