Seeds From the Deep Cosmos: An Interstellar Visitor Could Seed New Planets
An object from interstellar space is speeding through our inner solar system, a visitor unlike any we've seen. Most astronomers now contend it is a comet with unusual chemistry, though at least one scientist floated the possibility that it could be a remnant of an advanced extraterrestrial civilization—a notion NASA has dismissed as a flight of fancy. In a bold new idea presented at a recent meeting in Germany, astrophysicist Susanne Pfalzner proposed that objects like 3I/ATLAS could become the seeds of giant planets after being captured by the disks of dust and gas surrounding young stars. She argues that interstellar travelers could carry ready-made seeds that jump-start the formation of the next generation of planets, especially around higher-mass stars. The paper notes that the first interstellar visitor, 'Oumuamua', was about 330 feet in length, using that as a size benchmark.
In This Article:
What We Know About the Interstellar Visitor
3I/ATLAS—an interstellar intruder—was observed speeding through the inner solar system and is thought to be a comet with unusual composition. Some have floated extraordinary ideas, including the possibility that it could be a remnant of an advanced civilization, but NASA has disputed that claim as a flight of fancy. The event is compared to the 2017 interstellar visitor 'Oumuamua', which was about 330 feet long, offering a scale for what such travelers could look like. Astronomers are using powerful telescopes to study its trajectory and composition to understand its origin and nature.
Seed Theory: Interstellar Objects as Planet-Builders
At the Europlanet Science Congress and the Division of Planetary Sciences meeting in Germany, Pfalzner presented a provocative idea: interstellar objects captured in the protoplanetary disks around young stars could become the seeds of planets. "Interstellar space would deliver ready-made seeds for the formation of the next generation of planets," Pfalzner said. The theory argues that higher-mass stars are more efficient at capturing these objects, making seed-based planet formation particularly plausible around such stars. The models even envisage millions of objects around the size of 'Oumuamua' being captured and dispersed within disks, potentially jump-starting planet formation.
Why This Might Solve a Long-Standing Mystery
This hypothesis could help explain why gas giants seem to form so quickly around some stars. In the standard accretion picture, particles collide and stick, but simulations show material can bounce off or shatter instead of lumping together into planets. Gas giants like Jupiter are rare around M dwarf stars, which tend to be cooler and smaller, while larger, Sun-like stars host more frequent giant planets. The disks around these stars last only about two million years—an incredibly tight window for giant planets to develop. If interstellar seeds exist, they could provide the extra mass needed to accelerate formation and help reconcile observations with theory.
Next Steps: How Researchers Will Test the Idea
Pfalzner and her colleagues are now assessing how many captured interstellar objects could plausibly form into planetary bodies and how they would be distributed across distant stars’ disks. They aim to quantify the population of seeds and their influence on planet formation in different stellar environments. Beyond the numbers, the idea invites a broader reevaluation: interstellar visitors might be ordinary actors in shaping planetary systems across the galaxy.
