Earth May Not Be a Cosmic Fluke, New Solar System Simulations Suggest

New computer simulations that begin from thousands of randomized starting conditions, rather than assuming the outcome, suggest that Earth-like planets emerge naturally from the process of planet formation.

Nader Haghighipour, a planetary scientist at the University of Hawaii at Manoa, presented the simulations at the Origins 2026 conference in Paris. "After about thirty years of doing terrestrial planet formation in one specific way, we have reached a point where we realized that the modeling we have done in the past has many limitations and can't be pushed any further," he said.

Because no one knows the precise starting point of our solar system, or how objects of different sizes were originally distributed in its protoplanetary disk, Haghighipour and colleagues built models that start without any preset solar system and let the physics of planet formation take over. The team ran more than 1,000 simulations of the late stage of terrestrial planet formation, using a variety of distributions of planetesimals and planetary embryos in a disk with a non-uniform distribution of solid material.

Across the simulations, the formation of an Earth-like planet at one Earth-Sun distance emerged as a natural outcome. A Venus-like planet appeared in about 28% of the simulations, sometimes within the habitable zone and sometimes just outside it, while Mars-like small objects repeatedly appeared near its current orbit. Even a small variation in initial conditions could greatly change the final outcome, Haghighipour said.

Simulations that once took six to eight months to run can now be completed in six to eight weeks on current laptop computers. "There is no reason to believe that our Earth is a fluke," Haghighipour said.