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This was unprecedented. In 2017, astronomers discovered the first known interstellar object in our solar system: "Oumuamua, a mysterious cigar-shaped enigma, identified as our first visitor from outer space.
But just because 'Oumuamua was the first detected interstellar object, does not mean that it was the first already. In fact, just five years ago, the Earth's atmosphere was hit by something that might have come from our solar system – and we never realized it.
In a new article, two Harvard researchers suggest that a meteor that collided with the earth's atmosphere in January 2014 was in fact another interstellar traveler with distant and mysterious origins.
But unlike the mighty Oumuamua – which is on a 20,000-year trajectory that will eventually see it coming out of our solar system – the meteor's long journey was destined to be a one-way trip, ending five years ago like a fiery finish. object burned in the skies over Papua New Guinea.
While 'Oumuamua' is a large object and has been detected far away from Earth, the team behind the meteor hypothesis said that much smaller interstellar immigrants could be far more banal. and potentially exist much closer to home.
"Instead of looking very far in space and considering that there should be a greater abundance of interstellar objects smaller than" Oumuamua ", we thought:" Why do not not search locally and find those smaller interstellar objects when they collide with the Earth's atmosphere? & # 39; "first author, astronomer Amir Siraj said Newsweek.
In collaboration with astrophysicist Avi Loeb of Harvard, Siraj has explored a catalog of meteor impacts preserved by NASA's NEO (CNEOS) research center.
Hidden in the CNEOS data, there was one notable feature: a 2014 fireball that rushed to Earth at a speed of about 60 kilometers per second (37 m / s) when She has passed the Sun.
We can be grateful that this object is quite small (less than a meter in diameter in total), because if it had been considerably larger, it could have had a disastrous impact on the Earth's surface, rather than the effects harmless atmospheric pollution.
But this happy anti-climax is not the main thing to remember from the meteor's blazing speed.
When Siraj and Loeb calculated the orbital trajectory of the meteor as a function of its speed, their number suggested that the object was not orbital-bound to the Sun: it was traveling so fast before its inflamed end that it was slipping directly under the gravitational pull of the Sun.
The researchers suggest that for this to be possible, the meteor would have to come from somewhere else, well beyond our solar system.
According to their calculations, the speed of the meteor "implies a possible origin of the deep interior of a planetary system or a star in the thick disk of the galaxy of the Milky Way".
It's a crazy idea, but if the results remain purely hypothetical at the moment, Siraj and Loeb's paper – which has not yet been peer-reviewed – has been welcomed by some members of the astronomical community.
"I think it's reasonable to conclude that this very high-speed impactor is derived from the interstellar object population," explained theoretical astrophysicist Kat Volk of the University of London. Arizona, not involved in the study. National Geographic.
"I expect that interstellar objects will be sufficiently common – both for theoretical reasons and for the implications of 'Oumuamua – that I think that an interstellar origin is the only thing I can do. the simplest explanation of this racing car. "
But although the discovery of Oumuamua has definitely changed the landscape, helping to concretize the theoretical bases of interstellar migration, not everyone has the conviction that this 2014 racing car held such a fantastic passport.
"The result is interesting, but relies on measurements for a single event," said astronomer Eric Mamajek of NASA's Jet Propulsion Laboratory. Scientific news.
"Was the event a statistical fluke or an interstellar meteor?"
The jury is still not aware, but the hypothetical possibilities in this field of science are as attractive as an invitation to cross the stars.
According to the calculations of Siraj and Loeb, these interstellar bolide events would have occurred countless times in the history of the Earth and, anticipating future visits, we could learn a lot about the antecedents of these events. distant travelers.
"Future meteorological surveys could signal incoming objects with excessive heliocentric velocities for pre-impact observations," the researchers write.
"Spectroscopy of gaseous debris from these objects as they are consumed in the Earth's atmosphere would reveal their composition … Potentially, interstellar meteors could deliver life from another planetary system and promote panspermia . "
No matter how you look at it, amazing things happen to us.
The results are available on the pre-printed website arXiv and have been submitted to Letters from the Astrophysical Journal.
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