Scientists hurried to observe the object before it disappeared, moving at 196,000 miles per hour, and their observations caused more questions than answers about “strange”, as scientists called it. .
Now, the latest research suggests that it is a fragment of a Pluto-like planet in another solar system.
After the discovery, the object was nicknamed “Oumuamua, Hawaiian” for “a messenger who comes from the distant past.” At first, astronomers expected it to be a comet.
But the cigar-shaped object, reddish, elongated, dry, rocky, as thick as a three-and-a-half-story building the length of a city block, had no comet tail, and its falling motion could not be explained. And it was debated whether it was an asteroid or an interstellar comet.
And, of course, it was speculated that “Oumuamua was a type of alien probe.
“In many ways, Oumuamua looks like a comet, but it was quite strange in many ways that the mystery surrounded its nature and speculation was unleashed about what it was,” said Desch, who is also a professor at ASU. in a statement.
Clues to the missile effect
“Oumuamua distinguished itself from comets in several ways, including the fact that it had a lower speed when it entered our solar system. If it had traveled through interstellar space for over a billion years like a comet, it would have had a higher speed.
Its shape was flattened like a pancake, unlike comets that are like cosmic snowballs. The object also received a fairly large impulse, known as the “missile effect”, greater than that experienced by comets when their frosts vaporize as they encounter the sun.
The researchers wondered if “Oumuamua is made of ice with different compositions, which allowed them to calculate how quickly the ice will turn to gas as the object is thrown by the sun. This also allowed Desch and Jackson to determine the mass, shape and effect of the rocket and to assess how reflective the frosts were.
“We realized that a piece of ice would be much more reflective than people thought, which meant it could be smaller. The same rocket effect would then give Oumuamua a bigger, bigger push than he experiences. usually comets, “Desch said.
In our solar system, Pluto and Saturn’s moon, Titan, are mostly covered in ice with nitrogen. If the object is largely composed of nitrogen ice, it is possible that a solid piece of it was displaced from a Pluto-like planet after it was affected in another planetary system.
The same thing happened in our own solar system, including Pluto and Kuiper Belt objects. This belt removed from objects on the edge of our solar system once had more mass than now.
When Neptune migrated to the outer solar system billions of years ago, it disrupted the orbits of these objects that have remained since the formation of the solar system. Thousands of objects similar to Pluto, covered in ice with nitrogen, collided with each other.
If this could happen in our own solar system, it is very likely that the same event will happen in another solar system, which means that ” Oumuamua may be the first sample of an exoplanet born around another star, brought on Earth “, the authors wrote in the study.
“It was probably knocked down from the surface by an impact about half a billion years ago and thrown out of its parent system,” Jackson, also a researcher and researcher at ASU, said in a statement.
“Being made of frozen nitrogen also explains the unusual shape of ‘Oumuamua. As the outer layers of nitrogen ice evaporated, the shape of the body would become more flattened, like a bar of soap, as the outer layers cleaned. by use. “
Researchers have estimated that Oumuamua’s encounter with our sun caused him to lose 95% of his mass.
Foreign speculation
Theories that “Oumuamua is a foreign object or a piece of technology have circulated since the object appeared and form the basis of the new book” Alien: The First Sign of Intelligent Life Beyond Earth “by Avi Loeb, a professor of science at Harvard University.
There is no evidence that “Oumuamua is an alien technology,” said the researchers in this study, although it is natural for the first object observed outside our solar system to bring aliens to mind.
“But it’s important in science not to jump to conclusions,” Desch said. “It took two or three years to find a natural explanation – a piece of ice with nitrogen – that would match everything we know about ‘Oumuamua. That’s not so much in science and too early to say that I have exhausted all natural explanations “.
However, “Oumuamua was a unique way for scientists to study an object outside our solar system. Understanding more about “Oumuamua, which disappeared from view in December 2017, can shed more light on the formation and composition of other planetary systems.
“Until now, we have not been able to know if other solar systems have planets similar to Pluto, but now we have seen a piece of one pass on Earth,” Desch said.
Future telescopes, such as the Vera Rubin Observatory in Chile, will regularly monitor the entire visible sky in the southern hemisphere, increasing our ability to observe more interstellar objects entering our solar system. The observatory will be operational from 2022.
“It is hoped that in a decade we will be able to obtain statistics on what kind of objects pass through the solar system and whether pieces of nitrogen ice are rare or as common as we have calculated,” Jackson said. “In any case, we should be able to learn a lot about other solar systems and whether they have suffered the same types of collision histories as ours.”