Latest Comet 3I/ATLAS news: Closest approach to Earth this week

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2025-12-17T15:01:31.241Z

Who discovered Comet 3I/ATLAS?

(Image credit: ATLAS project/Gemini North Obervatory/Shadow the Scientists)

If you've been as captivated as us here at Space.com by comet 3I/ATLAS's trip through the solar system, you might find yourself wondering exactly how it was discovered. So did we, which is why our own Kenna Hughes-Castleberry took it upon herself to find out  —  and the result was eye-opening!

What seemed like a normal July night ended up making history when astronomer Larry Denneau at the University of Hawaii's Institute for Astronomy discovered a new moving object while scrolling through data from ATLAS — the Asteroid Terrestrial-impact Last Alert System."I was the person reviewing at the time that 3I popped out of the pipeline," Denneau told Space.com "And at the time, it looked like a completely garden variety new Near Earth Object."

Read the full story behind the discovery of comet 3I/ATLAS here.

2025-12-17T13:02:25.305Z

Comet 3I/ATLAS: An early Christmas gift for scientists

3I/ATLAS is currently racing away from the sun towards interstellar space.(Image credit: NASA Scientific Visualization Studio)

When 3I/ATLAS is closest to Earth on Dec. 19, all the features that we are looking for will be easier to detect with our telescopes and it has scientists as eager as kids on Christmas.

Comet 3I/ATLAS is the third large interstellar visitor (an asteroid or a comet) known to have passed through our solar system from beyond our solar system. By studying it closely, astronomers hope to learn more about other celestial objects through telescope observations.

"It has since been careening through the interstellar medium of the Milky Way galaxy for billions of years," Darryl Z. Seligman, an assistant professor of physics and astronomy at Michigan State University, wrote in an op-ed. "And we get front-row seats to watch as it gets close to our sun, for what is almost surely the first time it has ever gotten close to a star".

Read the full op-ed on the comet's Earth flyby here.

Tariq Malik

2025-12-17T11:58:04.035Z

Comet 3I/ATLAS has last hurrah this week

(Image credit: 3I/ATLAS inset (NASA, ESA, STScI, D. Jewitt (UCLA). Image Processing: J. DePasquale (STScI)). Graphic created in Canva Pro.)

Good morning, Space Fans! As of today, we are T-2 days until the interstellar comet 3I/ATLAS makes its closest approach to Earth and then we'll have to say our goodbyes.

Whether or not you're in Team Comet or Team "Could It Be A Spaceship?" 3I/ATLAS has dominated the comet conversation since its discovery on July 1 by the ATLAS telescope in Chile. On Friday, Dec. 19, 2025, the comet will be at its closest to Earth at a range of roughly 168 million miles (270 million kilometers) before heading out of our solar system for good.

Over the next two days, we'll chronicle comet 3I/ATLAS's Earth flyby, and revisit its passage through our solar system — and its legacy.

Read our full preview of the comet's Earth flyby.

Tariq Malik

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