The research, led by Konstantin Batygin of the California Institute of Technology (Caltech), suggests that the outer solar system’s dynamical lifetime is significantly shorter than previously projected.
For centuries, astronomers viewed Jupiter, Saturn, Uranus, and Neptune as the most durable machinery in the solar system, with orbits expected to outlast the universe many times over.
“Here we show that these estimates rest on the assumption that solar mass loss is smooth,” the authors write, referring to previous models, including a 2020 study by Jon Zink, Batygin, and Fred Adams of the University of Michigan, that estimated the solar system would break up approximately 100 billion years after the Sun becomes a white dwarf, accounting for the influence of passing stars.
The new work by Batygin, Jim Fuller of Caltech, and Adams dramatically shortens that clock.
The researchers calculated that the Sun may lose its mass in approximately 4,600 individual ejections, with each pulse representing about one ten-thousandth of the Sun’s original mass. These pulses create a recoil effect of roughly seven meters per second. In the most extreme cases, the outer solar system’s dynamical lifetime falls to about one billion years after the white dwarf forms—a scale roughly 100 times shorter than previous estimates.
The simulations demonstrate that the instability often begins before the Sun completes its transition. In 37 out of 48 runs of the favored scenario, orbits began to cross while the Sun was still a red giant, containing 89 percent of its current mass.
In approximately 40 percent of the scenarios, the system became heavily disturbed during the very formation of the white dwarf. By the time three billion years have passed following the white dwarf’s birth, nearly 90 percent of the simulated systems have collapsed.
The consequences for the outer planets are severe. “In nine out of ten of our simulations, at least one giant planet is hurled into interstellar space,” Batygin said.
The study highlights that because most stars end their lives as white dwarfs, these chaotic outcomes likely represent an astrophysical norm. The research offers details for exoplanet study, but the authors acknowledge their findings rely on the specific modeling of the Sun’s late-life mass loss.
If the actual solar ejections are significantly smaller in mass, the simulations indicate that more than 98 percent of systems would remain stable. The team emphasizes that while the Sun will consume its core hydrogen in roughly five billion years and subsequently swallow Mercury and Venus, the fate of the outer planets is now understood to be far more volatile than previously believed.
“The quiet retirement we imagined for planetary systems is a myth,” Batygin said.