A look at 3I/ATLAS from NASA.
An image interstellar Comet 3I/ATLAS captured by the Gemini South telescope in Chile, shows the comet’s tail. 3I/ATLAS is only the third confirmed interstellar visitor to our solar system.
Hubble captured this image of the interstellar comet 3I/ATLAS on July 21, 2025, when the comet was 277 million miles from Earth. Hubble shows that the comet has a teardrop-shaped cocoon of dust coming off its solid, icy nucleus.

A famous comet visiting from outside our solar system known as 3I/ATLAS is blazing through our cosmic neighborhood, leaving a striking trail in its wake.

A ground telescope in Chile recently glimpsed the comet's glowing tail, which observations reveal has steadily been growing as the interstellar interloper cruises toward the sun.

It's not often that a celestial object originating from another star makes its way to our solar system. Naturally, such a rare event prompts plenty of scientific inquiry and no end to wild theories – including an infamous one postulating that the object could be an alien spacecraft.

But the more observations scientists are able to record with both ground and space telescopes, the more they learn about comet 3I/ATLAS.

That includes the latest sighting from the Gemini South telescope in Chile, operated by the National Space Foundation’s NoirLab. Here's what the telescope observed about the comet's tail.

What is 3I/ATLAS comet?

A comet known as 3I/ATLAS made news in July when it was confirmed to have originated outside Earth's solar system, which makes it just one of three known interstellar objects ever discovered in our cosmic neighborhood.

Comet Oumuamua, Hawaiian for “scout” or “messenger,” became the first interstellar object ever detected in the solar system in 2017, followed by comet Borisov in 2019.

In the case of 3I/ATLAS, the object, which scientists estimate to be more than 12 miles wide, is whizzing at 130,000 mph on a trajectory that on Oct. 30 will bring it within about 130 million miles of the sun, according to NASA. It is expected to reappear in December on the other side of the sun, allowing for scientists to continue studying it.

A telescope in Chile – part of the NASA-funded Asteroid Terrestrial-impact Last Alert System, or ATLAS – was the first to spot what initially looked like an unknown asteroid on a path approaching Earth’s orbit.

The observation was reported to the Minor Planet Center, the official authority for observing and reporting new asteroids, comets and other small bodies in the solar system. The object, eventually confirmed to almost certainly be a comet and named 3I/ATLAS, was later confirmed to have interstellar origins after follow-up observations.

Ground telescope in Chile reveals glowing tail on interstellar visitor

The Gemini South's recent observations, made Aug. 27, show that 3I/ATLAS displays a broad coma, or a cloud of gas and dust that forms around the comet’s icy nucleus as it gets closer to the Sun. It also sports a prominent tail, NOIRLab said in a Thursday, Sept. 4 press release announcing the findings.

What makes the new observations significant is that the comet's tail is "significantly more extended" than it appeared in earlier images, suggesting that 3I/ATLAS has become more active as it travels through the inner solar system. What's more, data indicate that the dust and ice of 3I/ATLAS are similar to those of comets native to Earth's solar system, a sign that whatever process shaped its own native planetary system and stars are one in the same.

NASA space telescopes, including Hubble and James Webb, also imaged comet

Unlike comets bound to the sun's gravity, 3I/ATLAS is traveling on a hyperbolic orbit that will eventually carry it out of the solar system and back into interstellar space. That's why, even though the comet poses no threat to Earth, the world's astronomers and space agencies are racing to harness a rare opportunity to study planetary material that formed from another star.

A fleet of NASA space telescopes have already been returning plenty of images and data back to Earth gathered from glimpsing the comet.

NASA's iconic Hubble Space Telescope previously got a look at the comet in July, collecting data that allowed astronomers to estimate the size of the comet’s solid, icy nucleus as anywhere from 1,000 feet to 3.5 miles wide.

The James Webb Space Telescope then observed the interstellar object Aug. 6 in near-infrared light, followed by the newer SPHEREx telescope from Aug. 7-Aug. 15, to get a better idea of its physical properties and chemical makeup.

Eric Lagatta is the Space Connect reporter for the USA TODAY Network. Reach him at elagatta@gannett.com

This article originally appeared on USA TODAY: Has 3I/ATLAS' tail been growing? Telescope observations reveal how comet has changed

Reporting by Eric Lagatta, USA TODAY NETWORK / USA TODAY

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