Solar System Could Fall Apart 100x Faster, Study Says

The solar system just got a much shakier forecast. A new Caltech-led study says the planets could fall apart far sooner than anyone thought, and the culprit is the Sun's own messy death, according to ScienceAlert.

The timeline is billions of years, so nothing changes for anyone alive today. Still, the finding overturns a comfortable assumption that physicists have leaned on since Newton, and it reshapes how astronomers think about the end of planetary systems.

The old story: planets that basically last forever

For a long time, the outer solar system looked like one of the most stable regions imaginable. Modern math suggested the giant planets could stay stable for around a quintillion years, which is more than 70 million times the current age of the universe, as ScienceAlert reports. That figure made the giant planets look effectively permanent.

Even after factoring in the Sun's mass loss and passing stars, the architecture of the giant planets was expected to last roughly 100 billion years. The paper's abstract notes that those estimates rest on one big assumption: that the Sun sheds its mass smoothly.

That assumption is the whole ballgame. When the Sun runs out of hydrogen in about six billion years, it will puff up into a red giant and eventually shrink into a white dwarf, losing about half its mass along the way.

The twist: the Sun goes out kicking

The new paper, published in The Astrophysical Journal Letters by Konstantin Batygin and Jim Fuller of Caltech and Fred Adams of the University of Michigan, argues the mass loss will be lumpy instead. The model describes thousands of separate ejections rather than a gentle fade.

"The surprise is what happens when smoothness gives way to granularity: break the mass loss into discrete ejection events and the picture changes wholesale," Batygin told ScienceAlert. Each ejection nudges the Sun, which shifts its gravitational pull on every planet.

The team found evidence for this kind of recoil in data from the European Space Agency's Gaia observatory, which watched wide binary systems that include white dwarfs. Caltech has also described the idea, noting that dying Sun-like stars should get about 10,000 little kicks over hundreds of thousands of years, each at a pace of a few meters per second, according to the university's June 2026 announcement of Fuller's separate study on the process. Fuller compared that speed to a slow jogging pace for humans.

The result also connects to earlier observations of white dwarfs. According to the AAS Nova research highlight, the simulations showed that the behavior of the outer planets was largely tied to the ejection mass of each kick, and that very small kicks mimic the smooth mass-loss case. Larger kicks, by contrast, let the outer system disassemble on timescales of billions of years, as detailed by AAS Nova.

The numbers behind the chaos

In their main scenario, each kick ejects about one ten-thousandth of the Sun's mass, roughly 33 Earths. That adds up to around 4,600 recoils, with a median speed change of about 7 meters per second, according to the published paper. The authors write that individually the kicks are minuscule but collectively they are transformative.

Of almost 700 simulations, the team focused on 48 with the most realistic mass loss. In 37 of those, the outer planets start crossing orbits long before the Sun even finishes shedding its outer layers.

About 40 percent of runs end in disruption or violent scattering before the white dwarf forms, and around 90 percent self-destruct within three billion years of that moment. That is less than 10 billion years from now, versus the old, absurdly long timelines.

What the simulations show for Saturn and Neptune

The simulations show dramatic outcomes. Uranus and Neptune might swap places and even dive inside Jupiter's orbit. Saturn could be ejected and become a rogue planet drifting through deep space.

"We lose them. In nine out of ten of our simulations, at least one giant planet is hurled into interstellar space," Batygin said. He adds that this lines up with microlensing surveys hinting there may be as many free-floating planets in the galaxy as stars.

The authors even give Isaac Newton a belated win. "Newton's envisioned instability is real after all," they write. "He was mistaken only about the perpetrator." The threat is not a passing star but the solar system's own internal dynamics.

Why this matters beyond our backyard

The wider implication is that about 97 percent of stars die this way, Batygin said, and many planetary systems out there are more fragile than ours. "The quiet retirement we imagined for planetary systems is a myth."

It also helps explain where wandering worlds might come from. If dying suns routinely fling out giant planets, that could be a major source of the lonely planets astronomers keep spotting between the stars.

The scenario is a theoretical projection from simulations, not an observation of the future. The planets remain stable today, and the changes described would unfold over geological timescales far beyond human history.

Readers can find more space and physics reporting in the science coverage and the world news for other developments.