人类历史上发现的第三颗星际彗星 3I/ATLAS 展现出令人惊讶的化学成分。天文学家于 2025 年 12 月利用詹姆斯·韦伯太空望远镜对其进行详细观测，发现其碳和重氢（氘）的比例与太阳系内的彗星截然不同，这为研究太阳系外的古老环境提供了独特的契机。

观测数据显示，该彗星的氘含量比太阳系彗星高出约 30 倍，且仅含有极微量的碳-13。这些特征表明 3I/ATLAS 可能诞生于大约 100 到 120 亿年前宇宙恒星形成最鼎盛的「宇宙正午」时期，并在极度寒冷且未受恒星长期热源辐射的环境中保存至今。

此项研究由多国科学家合作完成，并得到了欧洲南方天文台甚大望远镜对氰化物中碳和氮同位素分析的支持。科学家指出，研究此类星际天体是理解银河系其他地方是否存在前生命化学物质，以及评估生命演化条件在宇宙中普适性的重要一步。

The third confirmed interstellar comet, 3I/ATLAS, has revealed an unexpected chemical composition. Astronomers observed the comet in December 2025 using the James Webb Space Telescope, capturing ratios of carbon and deuterium (heavy hydrogen) that differ significantly from those found in comets native to our Solar System.

Observations showed that the comet contains approximately 30 times more deuterium than Solar System comets and only trace amounts of carbon-13. These unique chemical signatures suggest that 3I/ATLAS formed 10 to 12 billion years ago during the "cosmic noon" of star formation, preserving its ancient chemical composition in a deeply frozen state.

This international research effort, supported by complementary observations of carbon and nitrogen isotopes using the European Southern Observatory's Very Large Telescope, helps scientists probe prebiotic chemistry. Studying such interstellar objects marks a crucial step in understanding the likelihood of conditions necessary for life to evolve elsewhere in the Universe.