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Argyre Planitia(ar -jÿr, air -) A 1000-km diameter basin in Mars' southern hemisphere, visible as a bright area to Earth-based observers and centered on the areographic coordinates 50° S latitude, 44° W longitude (see areography). Like Hellas Planitia it is probably an impact feature. See Mars, surface features.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006