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The first known interstellar visitor to our solar system is neither a comet nor an asteroid as was first suspected and does not look like a cigar in any way. A new study indicates that the mystery object is likely a remnant of a Pluto-like, cookie-shaped world.
Arizona State University astronomers reported this week that the bizarre 148-foot (45-meter) object appears to be made of frozen nitrogen, just like the surface of Pluto and Neptune’s largest moon, Triton.
Study authors Alan Jackson and Steven Desch believe an impact knocked over a piece of an icy nitrogen-covered planet 500 million years ago and sent the piece falling from its own star system, to ours. The reddish remnant is thought to be a fragment of its original self, its outer layers evaporated by cosmic radiation and, more recently, by the sun.
Its name is Oumuamua, Hawaiian for scout, in honor of the Hawaii Observatory which discovered it in 2017.
Visible only as a point of light millions of miles away on its closest approach, it was determined to come from beyond our solar system because its speed and trajectory suggested it was not turning around the sun or whatever.
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 didn’t fit into the known categories – it looked like an asteroid but sped like a comet. Unlike a comet, however, it had no visible tail. Speculation has swung between comet and asteroid – and it has even been suggested that it could be an alien artifact.
“Everyone is interested in extraterrestrials, and it was inevitable that this first object outside the solar system would make you think of aliens,” Desch said in a statement. “But it is important in science not to jump to conclusions.”
Using his sheen, size, and shape – and being propelled by leaking substances that didn’t produce a visible tail – Jackson and Desch designed computer models that helped them determine that Oumuamua was most likely a piece of nitrogen ice that was gradually eroding, in the same way. a bar of soap thins with use.
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 virtual this year.
Not all scientists buy the new explanation. Harvard University’s Avi Loeb disputes the results and supports his premise that the object appears to be more man-made than natural – in other words, something from an alien civilization, perhaps a light sail. His recently published book, “Alien: The First Sign of Intelligent Life Beyond Earth,” addresses the subject.
Given that Oumuamua is different from comets and asteroids – and something never seen before – “we cannot assume ‘business as usual,’ as many scientists argue,” Loeb wrote in an email on Wednesday. . “If we envision ‘something we’ve never seen before,’ we need to leave the artificial origin hypothesis on the table and collect more evidence on objects of the same class.”
When Oumuamua was at its closest approach to Earth, it appeared to be six times as wide as its thickness. These are the approximate proportions of a slice of an Oreo cookie, Desch noted.
It’s now long gone, beyond the orbit of Uranus, more than 3.2 billion miles away – and far too small to be seen even by the Hubble Space Telescope. As a result, astronomers will need to build on the original 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 have fallen to 10 to 1, according to Desch.
“So maybe Oumuamua was cookie compatible when we saw it, but will soon literally be as flat as a pancake,” Desch said in an email.
This is how the cosmic cookie – this one anyway – crumbles.
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