According to Michele Bannister, there are a myriad of these little worlds in our Solar System as of now. We simply cannot see them yet because we are not seeing faintly.
The difference between that and anything that could be measured lies in the mid-point of a question becoming increasingly important to small-body science: is the inside of the Solar System steadfastly permeated with interstellar debris particles born around other stars and thrown away and left to drift across space in uncircled orbits?
The population might be much larger than the small number of visitors that are known. Harvard astronomer Avi Loeb has suggested that the population might even be many times more concentrated than predicted by the handful of identified visitors. Based on two interstellar meteor candidates, CNEOS-22 (recorded in 2022 in the Pacific) and CNEOS-25 (recorded in 2025 in the Barents Sea), Loeb and others calculated that there was a background of some 35 million meter-scale interstellar bodies within Earth’s orbit. In such a framing, the atmosphere of the Earth is a survey tool: in case hyperbolic, fast meteors come in, once in, say, the span of a few years, then there may be much more other bodies of a similar type traversing the same space, most of which simply burn out.
These meteors are not hook-sized, but a few feet across but by their speed they are hook-like. To move at a speed exceeding the escape velocity of the Solar System, a small object should be unbound to the Sun. Suppose that such an inference is true, then all such meteors are time capsules that were formed under the radiation of a different star, its chemistry, and collisions and then flew by chance over a long period before hitting Earth. Loeb has proposed extracting material in these events at sea and dating it by radioactive methods to determine travelling times with a longer goal of tracking the migrations of solids between planetary systems.
The counterpart to this picture of the confirmed interstellar visitors already exists in the catalog of observed large, bright bodies that can be monitored over months. The third object to be known to lie outside our solar system is Comet 3I/ATLAS, which not only came with the privilege of being seen. The presence of several assets was observed and used to narrow down the size of it; to date, NASA reported an upper-limit nucleus diameter of 3.5 miles (5.6 kilometers), although it can be even smaller. The same overview observes that the nearest distance that the comet will be to the earth will remain very far away by approximately 1.8 astronomical units making the experience scientific but not hazardous.
These giant interstellar passers are few, but they hold the physics. By moving in a hyperbolic orbit, retrograde, one is out of the gravitational ownership of the Sun. The technical account then changes to Is it here? to What consists it, and how does it act in the presence of the sun? The point is in 3I/ATLAS not spectacle, but instrumentation. The space telescopes and planetary missions have conducted a wide observing campaign, which has provided a template of rapid characterization a practice run of the next discovery with a closer geometry and less warning or a less clearly defined signature.
The harder frontier is still small, weak interstellar bodies. The sky scans of the Vera C. Rubin Observatory were repeated and wide to extend into that regime, transforming the current haphazard detections into a more continuous progression of candidates. Should this occur, the argument of Loeb based on the meteors can be tested in a second manner: the rate by atmospheric entries can be compared to the census of optical surveys. Concurrence would enhance the argument of a congested inner Solar System; discord would narrow models of the frequency with which interstellar debris hits Earth, as well as the largest proportions of sizes prevail.
The implication of either of these outcomes will remain the same in the long run. Deep space is transformed into a delivery route by interstellar objects, be they kilometer-size comets observed over months, or meter-size meteors that take seconds. Every discovery makes the connection between formation of distant planets and the material that passes, unnoticed, by the Sun increasingly tight.
