Simulations suggest gravitational disturbances could disrupt the outer planets’ orbits about a billion years after the Sun becomes a white dwarf. That stage is billions of years away and poses no immediate risk to Earth.
The study by Konstantin Batygin, Jim Fuller and Fred Adams appeared in The Astrophysical Journal Letters. The researchers examined how solar mass loss and passing stars could affect Jupiter, Saturn, Uranus and Neptune.
In roughly five billion years, the Sun is expected to swell into a red giant, shed much of its mass and eventually become a white dwarf. The models considered in the study leave it with about 54% of its present mass. A weaker gravitational pull would expand the remaining planets’ orbits and make them more sensitive to outside disturbances.
The main change in the new calculations is that solar mass loss is treated as uneven. Earlier models generally assumed a smoother process. Euronews’ account of the study says the modeled scenario could bring instability in the outer system forward to around one billion years after the white dwarf forms, compared with much longer timescales in earlier estimates.
That timescale concerns the modeled future of the outer planets. It does not mean the entire solar system will disappear on a fixed date. The inner planets could face different outcomes during the red giant phase. Earth is expected to become uninhabitable as the Sun grows brighter, long before the white dwarf stage.
The research concerns the distant future and does not suggest that planetary orbits are changing dangerously now. Its outcome also depends on the assumptions used for solar mass loss and gravitational disturbances from other stars.