There may be 4 trillion alien ships in the solar system

 

4 trillion alien spacecraft. That's the number arrived at by calculations by the already famous Harvard astronomer Avi Loeb, who has published new research that has not yet been peer-reviewed.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 that visited our solar system in 2017, Oumuamua.

Data obtained from its passage suggested that it was a very strange object, the nature of which was — and still is — hotly debated by scientists.

It has been speculated, for example, that due to its cigar shape and unexpected accelerations, it could be some kind of alien probe.

And while Loeb didn't explicitly say that 'Oumuamua is an alien spacecraft per se, he strongly suggested that it could be and that we should be open to such a possibility.

In light of this perspective, you are now basically asking what self-respecting scientists dare not ask:

How many possible Oumuamuas could exist 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.

“It is possible to use recent detection rates of interstellar objects 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, bringing the total to four in eight years.

At that rate, Loeb and Ezeller calculated that there could be as many as 40 decillion interstellar objects throughout the solar system, including areas beyond the reach of our instruments.

That number drops to the more humble 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 billion 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.