4 trillion alien ships. That is the figure reached by the calculations of the already famous Harvard astronomer Avi Loeb, who has published new research that has not yet been peer-reviewed.
The study follows up on the first recorded discovery of an interstellar object to visit our solar system in 2017, Oumuamua.
The data obtained from its passage suggested that it was a very strange object, the nature of which has been—and still is—hotly debated by scientists.
It was speculated, for example, that due to its cigar shape and unforeseen accelerations, it could be an alien probe of some kind.
And while Loeb hasn’t explicitly said that Oumuamua is an alien ship per se, he has strongly suggested that it could be and we should be open to such a possibility.
In light of that perspective, you are now basically asking what selfrespecting scientists dare not ask:
How many possible Oumuamuas could there be in our solar system that go unnoticed?
To get an answer, Loeb and fellow Harvard astronomer Carson Ezell first looked at how many interstellar visitors we’ve already detected.
“One can use recent interstellar object detection rates and known capabilities to estimate the density of similar objects in the solar neighborhood,” they wrote in the study.
Since Oumuamua, astronomers have detected three more interstellar objects, making it four in eight years.
At that rate, Loeb and Ezeller calculated that there could be as many as 40 decillion interstellar objects in the entire solar system, including areas beyond the range of our instruments.
That number drops to the humblest of 4 trillion—that’s a 4 followed by 18 zeros (4^18)—when you limit the range to the “habitable zone” near the Sun, which is potentially exciting since, if some of them are aliens, they would be easier to spot.
Some of Loeb’s theories are borderline, but he never fails to make some fascinating points.
Even if most of the 4 trillion interstellar objects turn out to be just fragments of space rock—which Loeb admits is likely—that still leaves plenty of room for some of them to actually be spacecraft or probes from extraterrestrial civilizations.