CAPE CANAVERAL, Florida (AP) – The first known interstellar visitor to our solar system is neither a comet nor an asteroid as first suspected and bears no resemblance to a cigar. A new study says that the mysterious object is probably a remnant of a Pluto-like world and is shaped like a cookie.
Arizona State University astronomers reported this week that the strange 45-meter object, which appears to be made of frozen nitrogen, as well as the surface of Pluto and the largest moon Triton in Neptune.
The study’s authors, Alan Jackson and Steven Desch, believe that an impact tore down a piece of a planet covered in frozen ice 500 million years ago and sent the piece falling from its own star system to ours. It is believed that the reddish remnant is a piece of its original self, its outer layers evaporated by cosmic radiation and, more recently, by the sun.
It is called Oumuamua, Hawaiian for the scout, in honor of the Hawaiian observer who discovered it in 2017.
Visible only as a bright spot millions of miles away, it has been determined to originate beyond our solar system because its speed and path suggest that it does not orbit the sun or anything else.
The only other object confirmed to have deviated from another star system in ours is Comet 21 / Borisov, discovered in 2019.
But what is Oumuamua? It did not fall into known categories – it looked like an asteroid, but it accelerated like a comet. Unlike a comet, however, it did not have a visible tail. Speculation has flipped back and forth between the comet and the asteroid – and it has even been suggested that it could be an alien artifact.
“Everyone is interested in aliens, and it was inevitable that this first object outside the solar system would make people think of aliens,” Desch said in a statement. “But it’s important in science not to jump to conclusions.”
Using brilliance, size and shape – and that it was propelled by the escape of substances that did not produce a visible tail – Jackson and Desch designed computer models that helped them determine that Oumuamua is most likely a piece of nitrogen ice that it erodes gradually, as a tablespoon of soap is diluted with use.
Their two papers were published Tuesday by the American Geophysical Union and also presented at the Lunar and Planetary Science Conference, which was normally held in Houston but virtual this year.
Not all scientists buy the new explanation. Harvard University’s Avi Loeb disputes the findings and argues that the object appears to be more artificial than natural – in other words, something of an extraterrestrial civilization, perhaps a light sail. His new book, “Alien: The First Sign of Intelligent Life Beyond Earth,” addresses the subject.
Given that Oumuamua is different from comets and asteroids – and something that has not been seen so far – “we cannot assume ‘business as usual’, as many scientists claim,” Loeb wrote in an e-mail. mail wednesday. “If we contemplate ‘something we have never seen before,’ we must leave the hypothesis of artificial origin on the table and gather more evidence on objects in the same class.”
When Oumuamua was closest to Earth, it appeared to be six times as wide as its thickness. These are the harsh proportions of a wafer in an Oreo cookie, Desch remarked.
It has long since passed, beyond the orbit of Uranus, more than 3 billion kilometers away – and far too small to be seen, even by the Hubble Space Telescope. As a result, astronomers will have to rely on initial observations and hopefully continue to refine their analyzes, Jackson said.
By the time the object begins to leave our solar system around 2040, the width-to-thickness ratio will be reduced to 10-to-1, according to Desch.
“So maybe Oumuamua was in line with a cookie when I saw it, but it will soon be as flat as a pancake,” Desch said in an email.
This is how the cosmic cookie – this one anyway – shatters.
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