Earth and Mars may have formed through different mixtures of planetary building processes, despite developing side by side.

Earth and Mars formed near each other about 4.5 billion years ago, yet new research suggests they grew through very different processes.

“The most surprising result was that Earth and Mars appear to have formed in different ways. You might have expected that two planets formed side by side in the same solar system would share a more similar formation history,” says Professor Anders Johansen, who studies planet formation at the Globe Institute, University of Copenhagen. He co-led the new study with Assistant Professor Haiyang Wang.