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Interstellar Comet: Water 14 Times Heavier Than Earth's ⚡ экспресс

Original: "Isotopic Signature of Organic Molecules from Beyond the Solar System: An Enriched Methane D/H Ratio in the Interstellar Object 3I/ATLAS"
arXiv:2603.20445 · 2026-03-20 · CC BY 4.0 · ⏱ 1 min · Exoplanets Galaxies
The James Webb Telescope found a record amount of deuterium—heavy hydrogen—in the interstellar object 3I/ATLAS.
Abstract

Imagine a package from another star system that tells you how planets were born there. Scientists saw for the first time in the visiting comet 3I/ATLAS an unusually large amount of 'heavy' methane, which is like a pass to the cold outskirts of an alien world. It makes you wonder: if we built a ship to such a system, what would we find there?

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Comet 3I/ATLAS was spotted when it entered the Solar System from interstellar space. The James Webb Telescope split the light from its gas cloud into a rainbow—a spectrum—and in this pattern, the lines of rare molecules with deuterium (heavy hydrogen) appeared.

Deuterium in methane acts like a frozen thermometer: its abundance directly reveals the temperature at the moment of the comet's birth.

For 3I/ATLAS, this 'thermometer' is off the charts: for every 30 ordinary hydrogen atoms, there's one deuterium atom—in Earth's oceans, that ratio is hundreds of times poorer. This means the comet was born in the icy darkness of a distant protoplanetary disk—a region where planets are just beginning to coalesce from cosmic dust and gas. This alien world is far colder than the cloud that gave birth to our Sun and Earth.

🎯 The deuterium abundance points to a comet birth temperature below –250°C — colder than the eternal shadows on the Moon.

🎬 Interstellar wanderers like 3I/ATLAS come to life in the pages of science fiction: for example, in Arthur C. Clarke's novel 'Rendezvous with Rama'.

Scientists
Christian DopplerD. B. McLaughlinDidier QuelozMichel MayorR. A. RossiterAlbert Einstein
Tags
spectroscopy Water hydrogen JWST cosmic dust exoplanet
Laws
Doppler effectgravitational lensingKepler's third lawCoulomb's lawMaxwell's equationsPlanck's law
Original: arXiv:2603.20445 · CC BY 4.0 · bridge42worlds