3I/ATLAS is still showing a strange protrusion as it approaches Earth

The interstellar object 3I/ATLAS is expected to make its closest approach to Earth a few days from now, coming within just 167 million miles—a significant gulf, but only a stone’s throw on a cosmic scale.

It’s an exciting moment that will give astronomers an unprecedented opportunity to show ground- and space-based telescopes at an unusual visitor. They’ve been following the object, widely believed to be a comet, as it roars across the solar system for months.

Since NASA’s Hubble Space Telescope first looked at the object on July 21, scientists have noticed a strange protrusion protruding from the object, a second tail that counterintuitively points directly at the Sun, not far from it like the characteristic tails of familiar solar system comets.

According to Harvard astronomer Avi Loeb, this “anti-tail” “may be the result of increased mass loss on the side of the Sun’s face.” Futurism At the beginning of this year, which caused the large pieces to crumble. These larger pieces are less susceptible to being affected by the Sun’s radiation pressure, so they move more slowly and accumulate on the Sun’s face.

A month after its perigee, or closest pass to the Sun, observations still clearly show 3I/ATLAS’ anti-tail, as Loeb noted in a new update on his blog. The image, taken Dec. 13 by the Tirasak Thaluang telescope in Rayong, Thailand, “shows a prominent anti-tail pointing toward the Sun, unusual for comets,” he wrote.

Judging by “thousands of images” taken after Hubble’s July observations, which show 3I/ATLAS’ anti-tail, Loeb argued that it is “not a perspective effect,” but a “real physical jet.”

“Its nature is a mystery because gas and micrometer-sized dust particles are expected to be pushed away from the Sun by solar radiation pressure and the solar wind, creating the appearance of a tail — as is regularly seen in solar-system comets,” Loeb wrote.

As he tends to do, Loeb argued that there is still a chance that we might be looking at an alien spacecraft rather than a natural comet. He posited that the anti-tail “could be a cluster of objects that could fall behind 3I/ATLAS because of its non-gravitational acceleration away from the Sun,” he detailed in a yet-to-be-peer-reviewed paper.

However, others are not convinced of such a possibility, arguing that the object’s two tails are nothing out of the ordinary, despite 3I/ATLAS’ interstellar origin.

“It’s throwing dust particles out toward the Sun, because the day side of the nucleus is the hot side,” said UCLA astronomy professor and comet expert David Jewitt. The sky and the telescope Last month.

“All of these objects resemble normal or small-sized comet nuclei, are excited in sunlight and eject dust particles,” he added. “There’s nothing really shocking.”

In a September 29 blog post, Pennsylvania State University astronomer Jason Wright also criticized Loeb’s unusual conclusion that 3I/ATLAS could be an alien spacecraft, pointing to several previous observations of “uniform sunward accretion” caused by large, ejected dust grains that “we can’t overcome near the sun”. Comet.”

European Space Agency scientists have also suggested that the secondary, observed tail may be a “dust tail” made of small solid particles, typical of solar system comets.

Loeb himself also left all possibilities open, writing two other papers suggesting that the anti-tail is the result of “scattering of sunlight by ice flakes from the sun-facing side of 3I/ATLAS”.

“These tiny ice particles evaporate before being pushed back significantly by solar radiation pressure and so they never appear as traditional cometary tails,” he wrote in his latest blog.

However, Loeb argued that we should be prepared to expect the unexpected.

“By identifying anomalies, we can learn something new,” he concluded. “By ignoring them, we remain ignorant.”

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