Model predicts early disruption of the Solar System’s outer planets

Researchers estimate that the outer planets’ orbits could destabilise about a billion years after the Sun becomes a white dwarf. This is a distant-future simulation, not a threat to Earth today.

The study by Konstantin Batygin, Jim Fuller and Fred C. Adams has been accepted for publication in The Astrophysical Journal Letters and posted on arXiv. The authors revise earlier estimates of the outer planetary system’s stability. They say previous calculations assumed smooth solar mass loss, while separate ejections of material could cause repeated gravitational disturbances.

In the numerical models, mass loss gradually changes the orbits of the giant planets. In about five billion years, the Sun will begin expanding and evolving toward the white-dwarf stage. Some scenarios lead to orbit crossings and strong scattering while it is still a red giant. The authors found such events in about 40% of model realisations before white-dwarf formation, while around 90% show the outer planetary system breaking up within three billion years afterward.

La Nación also reports that the Sun could retain about 54% of its current mass by the end of its evolution. This loss changes planetary orbits and leaves outer bodies more vulnerable to disturbances from passing stars. The primary paper estimates the outer system’s previous dynamical lifetime at 10^18 years, while the new models reduce it to roughly one billion years after white-dwarf formation.

This is a probabilistic projection about the outer planets and their gravitational dynamics after the Sun evolves. It does not mean all planets will be ejected on the same schedule, and it is not an estimate of how long life on Earth will remain possible. The Sun’s brightening and expansion will affect the inner planets separately, before it becomes a white dwarf.