The origin and identity of a massive space object that flew past Earth in 2017 has remained a mystery ever since.
The object, called “Oumuamua – a Hawaiian name meaning” scout “or” messenger “- traveled on a trajectory that strongly suggested it came from another galaxy. That made it the first interstellar object ever detected.
But what was it? A few researchers, including Harvard University astronomer Avi Loeb, stated that the object was an alien spacecraft. Others suggested it was an asteroid, or perhaps an interstellar comet.
Now, a few articles published in a journal of the American Geophysical Union offer another theory: that ‘Oumuamua was shrapnel from a small planet in another solar system.
“We’ve probably solved the mystery of what ‘Oumuamua is, and we can reasonably identify it as a chunk of an’ exo-Pluto, ‘a Pluto-like planet in another solar system,” said Steven Desch, an astrophysicist in the state. Arizona. University and a co-author of the new study, said a press release.
A planetary fragment made from frozen nitrogen
Desch and his co-authors believe that half a billion years ago, a space object struck Oumuamua’s parent planet. That sent ‘Oumuamua to our solar system.
Once it approached the sun, they think, ‘Oumuamua accelerated as the sunlight evaporated his icy body. Comets follow a similar movement pattern known as the “missile effect”.
Because ‘Oumuamua’s composition is unknown, the researchers calculated which types of ice would sublimate (change from solid to gas) at a speed that could explain’ Oumuamua’s rocket effect. They concluded that the object is likely made of nitrogen ice, like the surface of Pluto and Neptune’s moon Triton.
An enhanced color representation of Pluto from NASA’s New Horizons spacecraft.
NASA / JHUAPL / SwRI
As it approached our solar system – and thus the sun – ”Oumuamua began to shed frozen nitrogen layers. The object entered our solar system in 1995, although we didn’t realize it at the time, then lost 95% of its mass and melted into a splinter, the study authors said.
It’s a comet. It’s an asteroid. No, it is neither.
An illustration of the space object ‘Oumuamua flying through the solar system in late 2017.
NASA / ESA / STScI
By the time astronomers became aware of ‘Oumuamua’ in 2017, it was already spinning away from Earth at 196,000 mph. So they only had a few weeks to study the strange object the size of a skyscraper. Several ground-based and one in space telescopes took limited observations as the object flew away, but astronomers could not fully examine it. ‘Oumuamua is now too far away and too weak to observe with existing technologies.
The limited nature of the information gathered left room for scientists to guess what the object might be and where it came from. Oumuamua was initially classified as a comet, but it didn’t appear to be made of ice and it didn’t emit gases like a comet would.
Oumuamua’s spin, speed, and orbit couldn’t be explained by gravity alone, suggesting it wasn’t an asteroid either. And the object’s shape and profile – it’s about a quarter of a mile long but only 34 feet wide – doesn’t match that of any previously observed comet or asteroid.
However, according to the authors of the new study, ‘Oumuamua’s frozen nitrogen composition could explain that shape.
“As the outer layers of nitrogen ice evaporated, the shape of the body would have become more and more flattened, much like a bar of soap does when the outer layers are rubbed away with use,” said Alan Jackson, another co-author of the study. in the release.
Some astronomers still think it was an alien ship
Unlike most space rocks, ‘Oumuamua appeared to accelerate rather than slow down in telescope observations.
That’s partly why Loeb thinks’ Oumuamua was an alien spacecraft. In a book he published in January entitled “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth,” Loeb describes Oumuamua as a defunct alien technology.
“The object has anomalies that deserve some attention – things that are not in line with the way we expected,” he told Insider in December. ‘Other people say,’ Let’s push those anomalies under the carpet of conservatism. ‘I have a problem with that, because if something isn’t right, you have to say it. “
An artist’s depiction of ‘Oumuamua.
ESA / Hubble; NASA; ESO; M. Kornmesser
Still, a 2019 study by an international group of astronomers analyzed all available Oumuamua data and concluded that Loeb’s theory was unlikely.
“We find no compelling evidence for an alien explanation for ‘Oumuamua,” the astronomers wrote.
Matthew Knight, a University of Maryland astronomer who co-wrote the study, put it this way: “This thing is weird and admittedly difficult to explain, but that doesn’t rule out other natural phenomena that might explain it.”