The Sun’s mass loss as it dies could destabilize the giant planets and ultimately break apart the outer Solar System, according to simulations described by IFL Science.
Although the Solar System’s structure has appeared unchanged for billions of years, recent astronomical research suggests that this stability is temporary. Earlier estimates suggested that the gas and ice giants could remain safely in their orbits even after the Sun’s transformation, for as long as a billion billion years. Over that immense timespan, the Sun would pass through its red giant phase, become a white dwarf and eventually cool completely into a black dwarf. The latest simulations suggest that its transformation could disrupt the gravitational balance far more violently than previously thought.
The inner planets face trouble well before that distant upheaval. Calculations suggest that Mercury, the smallest planet, has a fairly unstable orbit, with about a 1 percent chance of permanently leaving the Solar System within the next 5 billion years. A smaller subset of models also shows that this chaotic motion could lead to fatal collisions between Mercury, Venus, Earth or Mars.
The Sun’s death throes and the disruption of planetary orbits
Even if the inner system avoids that catastrophe, the Sun’s evolution will eventually reach these worlds. When it runs out of fuel for nuclear fusion, the Sun will swell into a vast red giant, extending beyond Venus’s orbit and probably Earth’s as well, engulfing those planets. It will then expel its outer gas layers into interstellar space as a spectacular planetary nebula. The remaining core will shrink into an extremely dense, hot white dwarf the size of Earth but 100,000 times as massive.
According to newer observations and models, this mass loss occurs not smoothly and steadily, but in sudden, chaotic episodes that could force the surviving distant bodies into drastically different orbits. Calculations suggest that gravitational resonances could develop between Jupiter, Saturn, Uranus and Neptune, potentially breaking apart the familiar planetary arrangement within a billion years of the white dwarf’s formation.
In the simulations, the ice giants frequently swap places. It’s also not uncommon for Uranus, Neptune or Saturn to be permanently ejected from the Solar System into interstellar space.
Was Newton right after all?
The findings offer a different view of how planetary systems evolve, revisiting an idea Isaac Newton had already suspected: that planetary orbits could inevitably fall out of equilibrium over time. But chaotic destruction doesn’t necessarily mean the story ends there. According to the report, observations around other white dwarfs demonstrate that new planets can form from debris left after a stellar cataclysm. The possibility that a second-generation planetary system might form from the Solar System’s remains during the chaotic era after the Sun’s demise therefore hasn’t been ruled out.
Source: IFL Science; photo: ESA / Stipa/Silicon Worlds
