Scientists unravel the secret of the mysterious Oumuamua, which was believed to be an alien ship

Scientists may have solved the mystery of the Oumuamua interstellar object, which in 2017 puzzled researchers and even led some to say that it was an alien spacecraft. The most surprising thing about this object was that its speed did not match the speed of any of the other objects observed before, and was even increasing.

After several years of research, Jennifer Bergner, an associate professor of chemistry at the University of California, Berkeley, and Darryl Seligman, a National Science Foundation postdoctoral fellow at Cornell University, published a theory in the journal Nature that could explain everything, disappointing ufologists.

What went wrong with Oumuamua

The first ever interstellar object to be observed unexpectedly appeared in the solar system in 2017 and immediately put scientists in a difficult position.

It was a 200-metre-long cigar-shaped rock that was first mistaken for an asteroid and then reinterpreted as a comet. During its journey through our solar system, it approached the Earth at a distance of 24 million kilometres and then flew out of the system.

Its entire journey past the Sun and Earth lasted about 80 days. During the observations of Oumuamua, astronomers found that it was moving in a so-called "hyperbolic" orbit, similar to a boomerang. It was thanks to this that scientists were able to establish for sure that the object did not come from our solar system, but only flew in the neighbourhood and would never be seen again.

But what surprised scientists even more was the speed of Oumuamua. In particular, the acceleration noticeable during the flight past the Sun. Scientists have long known that planets and stars can provide gravitational acceleration to comets or asteroids, but Oumuamua's speed of 87 kilometres per second did not fit into existing theories, being three times faster than the average comet in the Solar System.

There was also the possibility that the object was accelerating due to the evaporation of surface ice as it flew past the Sun, but in this case it should leave a visible tail. But nothing of the sort happened.

It is because of these nuances and the cigar-shaped shape of Oumuamua that scientists did not hesitate to suggest aloud that they were observing an alien craft equipped with an engine.

Why Oumuamua was accelerating

Now, Bergner and Seligman have come up with an idea that explains everything, but has only one minor problem.

"I've been trying to explain the gas emission for several years now. At first, I thought that maybe there just wasn't too much dust in the gas stream (to form a tail). Later, we thought that maybe it (Oumuamua) was made up of some more volatile material than what we see in normal comets, such as hydrogen, nitrogen or carbon monoxide. But there were theoretical problems with each of these explanations," Seligman told Space.

He noted that hydrogen needed extremely low temperatures to freeze to an object the size of Oumuamua, and scientists do not expect such temperatures inside the dense molecular clouds from which these objects are formed. Nitrogen is not abundant in the Milky Way.

The researchers then suggested that there might be nothing strange about the chemistry of Oumuamua.

"A comet travelling through the interstellar medium is essentially cooked by cosmic radiation, producing hydrogen as a result. We thought: if this is happening, can't it be trapped in the body so that when it enters the solar system and heats up, it releases this hydrogen?" - Seligman explained.

The calculations showed that, in theory, the force of this hydrogen release could explain Oumuamua's strange acceleration.

"Jennifer's idea is great because this is exactly what should be happening with interstellar objects. We had all these silly ideas about hydrogen icebergs and other crazy things, and this is just the most general explanation," Seligman said.

The only problem with this theory is that Oumuamua has disappeared from the solar system forever and it is no longer possible to prove it definitively. Scientists hope that another interstellar visitor will eventually arrive in the solar system, which will allow them to answer the questions that interest scientists.

Earlier, OBOZREVATEL also talked about the theory of scientists that there may be aliens in the solar system who launch probes to Earth.

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