The interstellar object 3I/ATLAS is expected to make its
closest approach to Earth mere days from now, coming within just 167 million miles — a significant gulf, but a mere stone’s throw on the cosmic scale.
It’s an exciting moment that’ll give astronomers an unprecedented chance to point both ground- and space-based telescopes at the unusual visitor. They’ve been following the object, which is
broadly believed to be a comet, for months now as it screams through the solar system.
Ever since NASA’s Hubble Space Telescope first gazed upon the object on July 21, scientists noticed a strange protrusion jutting out of the object, a second tail that counterintuitively points directly at the Sun, not away from it like the characteristic tails of familiar solar system comets.
This “anti-tail” could be the result of “enhanced mass loss in the Sun-facing side,” as Harvard astronomer Avi Loeb
told Futurism earlier this year, which causes larger fragments to be broken off. These larger fragments are less susceptible to being affected by the Sun’s radiation pressure, causing them to move more slowly and accumulate on the Sun-facing side.
Over a month after its perihelion, or closest pass of the Sun, observations still clearly show 3I/ATLAS’ anti-tail, as Loeb noted in a
new update on his blog. A December 13 image taken by the Teerasak Thaluang telescope in Rayong, Thailand
“shows a prominent anti-tail, uncommon for comets, pointing in the direction of the Sun,” he wrote.
Judging by the “thousands of images” taken since Hubble’s July observations, which show 3I/ATLAS’ anti-tail, Loeb argued that it’s “not a perspective effect,
” but a “real physical jet.”
