Sizing up Mars (image) University of Chicago Caption This image shows the relative size of the inner planets of the solar system (from l-r): Mercury, Venus, Earth and Mars. New research conducted by scientists at the universities of Chicago and Miami supports the idea that Mars owes its small size to its relatively rapid formation. Credit Lunar and Planetary Institute Usage Restrictions News organizations may use this image in connection with reports about the Mars research of Nicolas Dauphas and Ali Pourmand. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.