Could Alpha Centauri Be Sending Interstellar Objects to Our Solar System?

Interstellar objects, like the famous ‘Oumuamua, have passed through our Solar System before, but their exact origins remain a mystery. Some may have come from nearby star systems, others from more distant regions, and some could even originate from completely different galaxies.

Unfortunately, tracking ‘Oumuamua for further study is no longer an option. Its highly eccentric orbit has carried it too far from our reach, making it impossible for any spacecraft to catch up or any telescope to observe it. However, scientists don’t need to rely solely on large interstellar visitors—tiny particles from another star system may already be present in our Solar System, providing an opportunity for study.

The nearest stellar system to us is Alpha Centauri, a triple star system that is gradually moving closer to our Solar System. Traveling at a speed of approximately 79,000 kilometers per hour (about 49,709 miles per hour), it will reach its closest point to us in roughly 27,700 years. Given this movement, researchers Cole Gregg and Paul Wiegert from the University of Western Ontario sought to determine whether objects from Alpha Centauri might have already made their way to us and whether more could arrive in the future.

“A small number [less than 10 meteors] may currently be entering Earth’s atmosphere every year,” Gregg and Wiegert stated in a study that is set to be published in the Planetary Science Journal, “[and] is expected to increase as Alpha Centauri approaches.”

At around 5 billion years old, Alpha Centauri is a mature star system. Because of its age, most of the material from its protoplanetary disk has likely dispersed, meaning it is not expected to eject much debris into space. However, it is still possible that some material from Alpha Centauri exists in our Solar System, perhaps in the asteroid belt or the distant Oort cloud. The presence of multiple stars and planets in the system increases the likelihood that material has been scattered. Additionally, planets may orbit the system’s three stars, although none have been confirmed so far.

To explore whether Alpha Centauri could still be expelling material, the researchers used existing models that describe how star systems typically eject debris. These models suggest that, while only a small number of Alpha Centauri objects may reach Earth each year, there could already be as many as a million objects from the system—each over 100 meters in diameter—lurking in the Oort cloud. Even smaller particles may also be present.

However, detecting these objects presents a major challenge. The Oort cloud lies at the outer edge of the Solar System, making direct observation extremely difficult. But despite these challenges, detection is not entirely impossible. NASA’s New Horizons mission is equipped with a dust detector that has been gathering data on particles in the Kuiper Belt—remnants from the formation of our Solar System. Since the Oort cloud is even farther away, New Horizons could potentially extend its mission long enough to search for signs of material from Alpha Centauri, provided it has enough fuel to continue operating.

That being said, the existence of Alpha Centauri-originated objects in the Oort cloud remains uncertain. There is also the question of whether smaller particles from Alpha Centauri could even survive the journey to our Solar System. These particles might be deflected by magnetic fields, lose speed due to drag in the interstellar medium, or be destroyed by high-speed gas atoms or collisions with other particles.

If any particles from Alpha Centauri do manage to reach the inner Solar System, they would experience a significant increase in velocity due to the Sun’s gravitational pull. Hypothetically, interstellar comets could also bring additional material—if Alpha Centauri ejects as many comets as our Solar System does. However, these comets would be extremely difficult to observe, and whether they can be detected remains an open question.

“A thorough understanding of the mechanisms by which material could be transferred from Alpha Centauri to the Solar System not only deepens our knowledge of interstellar transport,” the researchers wrote in their study, “but also opens new pathways for exploring the interconnectedness of stellar systems and the potential for material exchange across the galaxy.”