Where an Interstellar Meteor Would Most Likely Strike Earth, According to New Simulations

Scientists still know very little about objects that arrive from beyond our Solar System. A team led by Darryl Seligman of Michigan State University modeled how hypothetical interstellar rocks would travel through the Solar System and where they would be most likely to collide with Earth.

The simulations show that the interstellar bodies most likely to pose a collision risk tend to have relatively low incoming speeds and trajectories that make them easier to perturb into Earth-crossing orbits by the Sun's gravity. The models also reveal a seasonal pattern: overall impact probability peaks when Earth faces the solar antapex (roughly Northern Hemisphere winter), while the fastest potential impacts are likeliest during spring as Earth moves toward the solar apex.

“The highest velocity impacts are most likely to occur in the spring when the Earth is moving towards the solar apex. However, impacts in general are more likely to occur during the winter when the Earth is located in the direction of the antapex,”

The researchers reasoned that many interstellar objects are probably ejected from M-type (red dwarf) star systems because these stars are the most abundant in the Milky Way. That statistical abundance increases the odds that small bodies originating near M-stars might be flung into interstellar space and later wander into our region. The Sun's motion through the galaxy — toward the solar apex and away from the antapex — affects the directions from which such objects are most likely to arrive.

One counterintuitive result of the study is that slower interstellar visitors pose a higher modeled risk than the fastest ones. Low relative speeds make it easier for the Sun's gravity to capture or strongly perturb an incoming object, altering its trajectory into an orbit that can intersect Earth's path. By contrast, known visitors such as 'Oumuamua and 2I/Borisov passed through on highly elongated, fast trajectories that kept them distant from Earth and reduced collision probability.

The simulations also predict a geographic pattern for impacts: strikes are most likely at low latitudes near the equator, with a modest bias toward the Northern Hemisphere. That northern preference arises from the orientation of the solar apex relative to Earth's orbit and the distribution of likely incoming directions.

It’s important to stress that these results are probabilistic and hypothetical. Direct detections of interstellar meteors remain elusive: despite long-standing searches, there are no conclusive detections of interstellar meteors to date. Current interstellar visitors, such as 3I/ATLAS, are being closely monitored but do not indicate an imminent risk to Earth.

Still, the study provides a useful framework for anticipating the properties, timing and likely locations of any future interstellar object that might threaten Earth. The findings can inform observing strategies and risk assessment even as uncertainties about interstellar populations persist.

Credit: Study led by Darryl Seligman (Michigan State University).