A new astronomical study suggests that Earth could one day be ejected from the solar system, not by the aging of the Sun, but by the unpredictable trajectory of a rogue star. While such a scenario unfolds over billions of years, researchers are now modeling just how much these cosmic interlopers could destabilize planetary orbits—and the findings are far from reassuring.
How Stellar Flybys Disrupt Planetary Orbits
Traditionally, simulations of the solar system’s evolution have considered it as a mostly isolated system. Yet, the Milky Way is teeming with stars, some of which pass dangerously close to our neighborhood. These stellar flybys, though usually inconsequential, could have profound effects on the delicate gravitational balance that holds the planets in place.
A new study published in the journal Icarus explores this possibility using 2,000 simulations run through NASA’s Horizons System, a highly precise tracking tool from the Solar System Dynamics Group. By introducing near-passing stars into these models, scientists discovered that such encounters could decrease the solar system’s long-term stability by about 50%. This instability isn’t uniform across planets, and some are more vulnerable than others.
Mercury Might Be Our Solar System’s Silent Killer?
Among all planets, Mercury stands out as the most unstable. Its orbit is already subject to increasing eccentricity—meaning it becomes more elliptical over time. This natural instability raises the possibility of Mercury colliding with Venus or plunging into the Sun. The presence of a nearby rogue star only amplifies this risk.
As the simulations suggest, Mercury is frequently lost in these scenarios, alongside Mars, which also faces a relatively high risk of ejection. Even Pluto, though now classified as a dwarf planet, has a 3.9% chance of being completely flung out of the solar system. While Earth shows a lower instability rate in these simulations, its orbit becomes increasingly vulnerable if another planet—destabilized by a stellar flyby—collides with it or alters its trajectory.
Stellar Versus Internal Chaos: Which is More Violent?
The study makes a clear distinction between two types of orbital instabilities: those generated internally within the solar system, and those caused by external stellar influences. According to the researchers, “the nature of stellar-driven instabilities is more violent than internally driven ones.” In the case of stellar flybys, multiple planets are often lost, with such outcomes occurring about half the time. In contrast, internally driven chaos rarely leads to the same level of planetary disruption.
A striking revelation from the study is that Earth’s chances of orbital instability caused by external stellar encounters are hundreds of times higher than previously believed—a finding that significantly redefines how scientists view the long-term stability of planetary systems.
A Sobering Look At The Cosmic Neighborhood
Though these events are projected to unfold over the next five billion years, the study adds another layer of existential vulnerability to our cosmic perspective. The Earth may not need to wait for the Sun to become a red giant to face its end. A random field star, drifting too close for comfort, might be enough to send our home planet drifting through the cold, empty void of interstellar space.
Stop with this blatant fear mongering. You’re a science site, not a propaganda machine. 5 BILLION years is when this is supposed to happen. 5 BILLION years. Humanity is closer to the first dinosaurs in regards to time than we are to this happening. In fact, the chances of humanity even existing in 5 billion years is almost zero. Stop with this fear mongering.