在遥远的系外行星上发现了甲烷
(原标题: Methane Discovered on Distant Exoplanet)
2023-09-20
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还有什么地方可能存在生命？2019年，在遥远的系外行星K2-18b的大气层中发现了大量的水蒸气，这是人类最伟大的悬而未决的问题之一，寻找太阳系外生命可能生存的行星。这颗行星和它的母星K2-18位于距离狮子星座124光年的地方。这颗系外行星比我们的地球大得多，质量也大得多，但它的轨道在其母星的宜居带。K2-18虽然比我们的太阳更红，但在K2-18b的天空中闪耀着与地球天空中的太阳相似的亮度。2019年大气中水的发现是在哈勃、斯皮策和开普勒三个太空望远镜的数据中发现的，通过注意到行星在恒星前面移动时对水蒸气颜色的吸收。现在到了2023年，韦伯太空望远镜在红外光下的进一步观测发现了其他指示生命的分子的证据，包括甲烷。这幅特色插图描绘了最右边的系外行星K2-18b，它被一颗卫星（中间）环绕，它们一起围绕着左下角的一颗红矮星运行。
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Where else might life exist? One of humanity's great outstanding questions, locating planets where extrasolar life might survive took a step forward in 2019 with the discovery of a significant amount of water vapor in the atmosphere of distant exoplanet K2-18b. The planet and its parent star, K2-18, lie about 124 light years away toward the constellation of the Lion (Leo). The exoplanet is significantly larger and more massive than our Earth, but orbits in the habitable zone of its home star. K2-18, although more red than our Sun, shines in K2-18b's sky with a brightness similar to the Sun in Earth's sky. The 2019 discovery of atmospheric water was made in data from three space telescopes: Hubble, Spitzer, and Kepler, by noting the absorption of water-vapor colors when the planet moved in front of the star. Now in 2023, further observations by the Webb Space Telescope in infrared light have uncovered evidence of other life-indicating molecules -- including methane. The featured illustration imagines exoplanet K2-18b on the far right orbited by a moon (center), which together orbit a red dwarf star depicted on the lower left.