New Southwest Research Institute (SwRI) modeling, conducted in collaboration with scientists at the University of Arizona, shows fundamental differences in how the moon may have formed from the giant impact that created the Earth–moon system. The new results used state-of-the-art computational techniques that factor in the material strength of the two colliding planets. These impact simulations could change how researchers understand moon formation and may help constrain the timing of the event. The research is published in The Astrophysical Journal Letters.

“We discovered that the preexisting geology of the Mars-sized proto-moon matters,” said Dr. Adeene Denton, formerly a NASA Postdoctoral Program fellow at SwRI and now a postdoctoral researcher in SwRI’s Solar System Science and Exploration Division. “When you simulate the Earth and the moon as colliding bodies with geologic properties, it changes how the moon forms out of that impact—that’s something we considered unnecessary before.”

Earlier studies of the giant impact scenario included a foundational 2001 paper by Dr. Robin Canup, vice president of SwRI’s Solar System Science and Exploration Division in Boulder, Colorado, and Dr. Erik Asphaug, a professor at the University of Arizona and co-author of the current study.