New evidence challenges the idea that Earth and Mars formed the same way

Earth and Mars emerged from the same swirling disk of gas and dust, separated today by less than 80 million kilometers at their closest approach. Their common birthplace might suggest that the two rocky planets were assembled through broadly similar processes.Their chemistry tells a different story.A University of Copenhagen-led study finds that Earth appears to have been built primarily from large protoplanets that themselves grew by sweeping up millimeter- to centimeter-sized pebbles. Mars, by contrast, acquired most of its mass from collisions with much larger building blocks called planetesimals.Published in Nature Astronomy, the research supports a hybrid picture of rocky planet formation in which pebble accretion and collisions both matter. Crucially, their relative importance may vary dramatically from one planet to another.“The most surprising result was that Earth and Mars appear to have formed in different ways,” Professor Anders Johansen told The Brighter Side of News.