Back in 2017, mankind witnessed something in space that was never before observed: a strange object zooming through our cosmic neighborhood that did belong there.
When it was spotted by a telescope in Hawaii, astronomers initially thought it was a large asteroid, then a large comet until a few studies later, and based on astronomical observations, astrophysicists proposed it may have been an alien spacecraft.
As bizarre as the theory sounds, the idea that ‘Oumuamua was an alien craft—or at least part of one—was something that a few scientists thought possible for quite some time.
We observed the object as it made its way through space, and even spotted a bizarre acceleration when it was moving away from the Sun.
These, as well as other facts, led some to believe that ‘Oumuamua was a mysterious piece of alien tech, perhaps sent to our solar system to study us in disguise.
Then, a few studies later, all of this was dismissed by experts who said that although strange, ‘Oumuamua is likely no more than a strange comet that lacks a tail; an interstellar visitor expelled from its home system millions—perhaps billions—of years ago, wandering through interstellar space, and dropping by distant star systems from time to time.
Eventually, scientists agreed that ‘Oumuamua was—likely—just a comet and no more than that, shattering the dreams of alien hunters who were eager to meet our cosmic brethren.
Over time, the comet hypothesis seemed to stand out among the proposals, but with a serious problem: there was no evidence that it had the classic tail that is always observed in this type of body, generated by its heating when approaching the Sun.
Then, in June earlier this year, a research team formed by astrophysicists Darryl Seligman and Gregory Laughlin believed they solved the problem, suggesting that the strange behavior observed by ‘Oumuamua was likely due to the comet being mostly molecular hydrogen (H2) and it had been escaping imperceptibly from its surface, causing the acceleration – and explaining the lack of a cometary tail.
To me, an ordinary blogger, that made sense.
That is until I read a new theory proposed by astrophysicists Avi Loeb and Thiem Hoang, who argue that the molecular hydrogen hypothesis is not possible in the real world.
Why? The researchers point out that, even in the coldest parts of space, starlight would heat up tiny fragments of solid hydrogen before they could clump together and form a comet the size of Oumuamua (400 to 800 meters).
More importantly, the journey from the nearest giant molecular cloud – a dusty, gaseous region where these hydrogen “icebergs” would form – is too long.
A hydrogen iceberg traveling millions of years through interstellar space would disintegrate, being eventually cooked by starlight.
Alien theory awakens.
Seligman responded that Loeb and Hoang’s analysis is correct and that no hydrogen comet would survive such an extended journey.
Seligman’s hypothesis works if Oumuamua is only 40 million old. On that time scale, degassing could have shaped the comet into that elongated shape without completely destroying it.
The researcher pointed out several nearby star origins for the comet, including Carina and Columba, two groups of young stars. However, Loeb disagrees; “Shortening the distance traveled by ‘Oumuamua does not solve the problem, because it must have formed together with its planetary system of origin, billions of years ago. With the passing of such eons, such a cosmic iceberg would evaporate.”
The astrophysicist also added that such hydrogen iceberg comets are expected to come from giant molecular clouds, and not from parts of space like Carina or Columba. Reiterating that this being the case, the trip from the nearest molecular cloud would see ‘Oumuamua not survive the journey.
And Loeb seems to be clear about what Oumuamua was, and the title of his next book, ready for publishing in 2021, says it all: Extraterrestrial: The First Sign of Intelligent Life Beyond Earth.
I am eager to read Loeb’s book and dive into the mind of a brilliant astrophysicist who will certainly leave us wanting for more.
As for ‘Oumuamua, I love the idea that, at least for now, we can actually ponder about what it means to have been visited by something that was likely artificially made, and not from Earth.