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3I/ATLAS: Tails of an Interstellar Comet

December 1, 2025

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Selected image source ↗ APOD published December 1, 2025. Credit: Victor Sabet & Julien De Winter. A publication-date match, not a photo taken on your date. Independent of NASA.

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3I/ATLAS: Tails of an Interstellar Comet

Original APOD · December 1, 2025 ↗

Read the original APOD for the astronomer’s explanation and full image credits. Its text is preserved in the archive as published.

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How typical is our Solar System? Studying 3I/ATLAS, a comet just passing through, is providing clues. Confirmed previous interstellar visitors include an asteroid, a comet, a meteor, and a gas wind dominated by hydrogen and helium. Comet 3I/ATLAS appears relatively normal when compared to Solar System comets, therefore providing more evidence that our Solar System is a somewhat typical star system. For example, Comet 3I/ATLAS has a broadly similar chemical composition and ejected dust. The featured image was captured last week from Texas and shows a green coma, a wandering blue-tinted ion tail likely deflected by our Sun's wind, and a slight anti-tail, all typical cometary attributes. The comet, visible with a telescope, passed its closest to the Sun in late October and will pass its closest to the Earth in mid-December, after which it will return to interstellar space and never return. Explore the Universe: Random APOD Generator

Image credit: Victor Sabet & Julien De Winter

Explore December 1 in other years · 31 APOD entries, 1995–2025

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