More than 30 years ago, NASA's Magellan spacecraft visited Venus and captured images as it orbited Earth's twin. Scientists recently examined archival data from the Magellan mission and discovered one of Maat Mons' volcanic vents changed shape and enlarged over a period of less than a year. Research professor Robert Herrick manually compared images from different Magellan orbits around Venus and found two images of Maat Mons taken eight months apart showing signs an eruption had occurred. Herrick collaborated with JPL's Scott Hensley to create computer models to test various geological scenarios that could account for the change in the vent shape and size. "Only a couple of the simulations matched the imagery, and the most likely scenario is that volcanic activity occurred on Venus' surface during Magellan's mission," reported Hensley.