Hellas Planitia

(hell -as) A vast, roughly circular impact basin in Mars' southern hemisphere, located in the planet's southern highland region at the areographic coordinates 40° S latitude, 290° W longitude (see areography). It can be seen as a bright area from the Earth and is the largest impact feature on the planet. It is thought to be the result of an asteroidal impact about 3900 million years ago during the heavy bombardment phase of the formation of the Solar System. The crater excavated by the asteroid is about 9 km deep and 2100 km in diameter and is girdled by a ring of material forming an elevated rim that reaches a height of about 1.5 kilometers above the level of the surrounding area. See Mars, surface features.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

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Using satellite images, researchers spotted fields of ghost dunes pitting the surface of two different regions on Mars: 480 potential dune molds at Noctis Labyrinthus, a mazelike region of plateaus and canyons, and 300 in the Hellas Planitia, a smooth 4-billion-year-old crater.

'Ghost Dunes' Spotted on Mars

These remanent fields are absent from Hellas Planitia as well as several other large impact basins.

Deciphering Mars: NASA's new mission to the Red Planet will help reveal why our neighboring world went red and dead

A series of sedimentary deposits indicates the presence of large standing bodies of water in Hellas Planitia located in the southern hemisphere of Mars, said by Dr.

Existence of historic lakes on Mars confirmed

Even at the bottom of the Hellas Planitia, the largest impact crater in the solar system, the pressure is estimated at just 1.1% of Earth standard.

Curiosity's Latest Findings Suggest Mars' Atmosphere Was Once Much More Like Ours

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