The Sun will not go quietly, and neither will the planets that circle it. A study led by Konstantin Batygin, a planetary astrophysicist at Caltech, finds that the outer solar system could come apart roughly a billion years after the Sun becomes a white dwarf, far sooner than earlier work had suggested.
The paper, “Terminal Instability of the Solar System Triggered by Stochastic Solar Mass Loss,” appeared in Astrophysical Journal Letters on September 21, 2026. Batygin wrote it with Jim Fuller of Caltech and Fred C. Adams of the University of Michigan. Their target is Jupiter, Saturn, Uranus and Neptune.
Why the old timeline was too slow
A 2020 study by Zink, Batygin and Adams, which counted the tug of passing stars, put the breakup at around 100 billion years after the white dwarf forms. Calculations from the late 1990s that ignored stellar mass loss gave a quintillion years. Against both, a billion years is abrupt.
The difference lies in how a dying star sheds its weight. Earlier dynamical work assumed the Sun would lose roughly half its mass smoothly, letting the giant planets drift outward and roughly double their orbits while the overall layout held steady. The new paper calls that unrealistic. Stars on the red-giant and asymptotic-giant branches lose material in separate bursts, thousands of them, and each burst is lopsided. Each one gives the planets a small gravitational shove, and in a chaotic many-body system small shoves add up.
There is observational backing. Gaia measurements of white dwarfs in wide binary systems show newly formed white dwarfs recoiling at about 0.75 km/s, within a permitted range of roughly 0.25 to 4 km/s. That is what lopsided final ejections would produce. “What we’ve shown is that this timeline gets front-run by the Sun’s own death,” Batygin told Gizmodo.
672 simulations, three outcomes
The team ran 672 simulations across a range of ejection masses and timings, following each for 3 billion years past white-dwarf formation. Results sorted by how much mass each burst carries away.
Bursts of 10-7 solar masses or less left the planets stable, much as in the smooth case. Between 10-7 and 10-6, about one run in five fell into mean-motion resonances, where orbital periods lock into small whole-number ratios. Resonance did not help. Those runs were slightly more likely to disintegrate than the others, which cuts against the intuition drawn from Pluto’s stable 2:3 lock with Neptune. At 10-5 and above, most runs ended badly.
Stellar models and the observed kicks point to about 10-4 solar masses for the Sun, which is the most destructive regime. At that value roughly 96 percent of simulated systems turned unstable within the 3 billion years. About 40 percent were disrupted or violently scattered before the white dwarf even formed, while the Sun was still a red giant. Put another way, only around 4 in 100 survived the full run.
How it might end
“Because planetary dynamics is chaotic, exhibiting sensitive dependence on initial conditions, no single simulation tells you what will happen, only what could happen,” Batygin told Gizmodo. The outcomes varied. Some planets were flung out of the system on hyperbolic paths after close encounters. In other runs Uranus and Neptune swapped places. Some arrangements looked tidy straight after the Sun’s mass loss and then unravelled slowly over billions of years.
The authors say the Sun’s own convulsions beat passing stars to the job by a factor of about 100. “In short: as the Sun dies, it will take the outer solar system down with it,” Batygin said.
Polluted white dwarfs and rogue planets
The result may also explain an old puzzle. Between 25 and 50 percent of observed white dwarfs show calcium, iron and magnesium in their spectra, elements that should sink out of sight within thousands of years. Something has to keep supplying them. The leading idea is that asteroids, comets or broken planets get pushed onto orbits close enough to be shredded by tides. Planetary instability that plays out over billions of years would keep that supply running. Surveys from the Sloan Digital Sky Survey and ESA’s Gaia have catalogued thousands of polluted white dwarfs. The team also sees a possible, unproven link to free-floating planets found by microlensing programmes such as MOA and KMTNet.
No cause for alarm
The work is theoretical. It models idealised systems, and the Sun’s true ejection mass is inferred rather than observed. Some simulated systems did stay stable, so ours could be among them. And the timescales are enormous: the Sun’s red-giant expansion is about 5 billion years off, and white-dwarf formation comes 1 to 2 billion years after that. Mercury and Venus are expected to be engulfed in the expansion, and Earth would survive it only as a scorched, airless remnant.
