CAPE CANAVERAL, Fla. (AP) – The first known interstellar visitor to our solar system is not a comet or asteroid as previously suspected and looks nothing like a cigar. A new study says the mystery object is likely a relic of a Pluto-like world and shaped like a cookie.
Astronomers at Arizona State University reported this week that the strange 45-meter (148-foot) object that appears to be made of frozen nitrogen, like Pluto’s surface and Neptune’s largest moon, Triton.
The authors of the study, Alan Jackson and Steven Desch, believe that an impact 500 million years ago smashed a chunk of a nitrogen-covered planet with ice and tumbled the piece from its own star system to ours. The reddish remnant is believed to be part of its original self, the outer layers of which have been evaporated by cosmic rays and, more recently, the sun.
It’s called Oumuamua, Hawaiian for scout, in honor of the Hawaii observatory that discovered it in 2017.
Visible only as a point of light, millions of miles away from the nearest approach, it was determined to have originated outside of our solar system because its speed and path suggested it was not orbiting the sun or anything else.
The only other object confirmed to have drifted from another galaxy to ours is Comet 21 / Borisov, discovered in 2019.
But what is Oumuamua? It didn’t fit well-known categories – it looked like an asteroid but flew like a comet. However, unlike a comet, it did not have a visible tail. Speculation alternated between comet and asteroid – and it was even 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 its brilliance, size and shape – and that it was propelled by escapes that did not produce a visible tail – Jackson and Desch came up with computer models that helped them determine that Oumuamua was most likely a lump of nitrogen ice that gradually eroded, like a bar of soap becomes. thinner when used.
Their two papers were published Tuesday by the American Geophysical Union and also presented at the Lunar and Planetary Sciences Conference, usually held in Houston, but virtually this year.
Not all scientists buy the new statement. Avi Loeb of Harvard University disputes the findings, insisting that the object appears more artificial than natural – in other words, something from an alien civilization, perhaps a light sail. His recently published book “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” is on the topic.
Given that Oumuamua is different from comets and asteroids – and something that has not been seen before – “we cannot assume business as usual, as many scientists claim,” Loeb wrote in an email Wednesday. “When we think about ‘something we hadn’t seen before’, we should leave the artificial origin hypothesis on the table and gather more evidence about objects of the same class.”
When Oumuamua was closest to Earth, it was found to have a width six times its thickness. Those are the raw proportions of one wafer of an Oreo cookie, Desch noted.
It is long gone now, beyond Uranus’ orbit, more than 2 billion miles (3.2 billion kilometers) away – and far too small to be seen, even with the Hubble Space Telescope. As a result, astronomers will have to rely on the original observations and hopefully continue to refine their analyzes, Jackson said.
By the time the object leaves our solar system around 2040, the width to thickness ratio will have dropped to 10 to 1, according to Desch.
“So maybe Oumuamua was consistent with a biscuit when we saw it, but will soon be literally as flat as a pancake,” Desch said in an email.
That’s the way the cosmic cookie – this anyway – crumbles.
The Associated Press Department of Health and Science is supported by the Science Education Department of the Howard Hughes Medical Institute. The AP is solely responsible for all content.