The Search for Another Earth-Like Planet Just Took a Big Step Forward

寻找另一颗类地行星迈出了重要一步

Astronomers have confirmed for the first time the existence of a rocky planet with an atmosphere that also happens to be in what’s known as the habitable zone. 天文学家首次证实了一颗岩石行星的存在，它不仅拥有大气层，而且恰好位于所谓的“宜居带”内。

Located 48 light-years away, the exoplanet—that is, a planet outside our solar system—may be the most similar thing to Earth that researchers have come across. If not a twin then certainly a family member. 这颗系外行星（即太阳系以外的行星）距离地球 48 光年，可能是研究人员迄今为止发现的最像地球的天体。如果说它不是地球的“孪生兄弟”，那至少也是“家族成员”。

Researchers at the Harvard-Smithsonian Center for Astrophysics were able to detect signatures of helium around LHS 1140 b, an exoplanet circling a cool red dwarf. The previously identified body has a rocky composition and is far enough from its host star to be able to retain liquid water on its surface. The team documented their findings in the journal Science this week. 哈佛-史密松天体物理中心的研究人员在 LHS 1140 b 周围探测到了氦气的特征，这是一颗围绕一颗冷红矮星运行的系外行星。这颗此前已被发现的天体具有岩石成分，且距离其主恒星足够远，能够在其表面保留液态水。研究团队本周在《科学》杂志上发表了他们的研究结果。

The presence of an atmosphere is essential for a planet to support life as we know it. On Earth, for example, the atmosphere allows water to remain in a liquid state, rather than boiling or sublimating easily. It also helps maintain a stable climate by regulating the planet’s temperature and reduces the impact of harmful space radiation. 大气层的存在对于行星维持我们所知的生命至关重要。以地球为例，大气层使水能够保持液态，而不是轻易沸腾或升华。它还有助于通过调节行星温度来维持稳定的气候，并减少有害空间辐射的影响。

Astronomers searching for habitable planets typically look for Goldilocks-type conditions that could be just right for life. LHS 1140 b is the first exoplanet to provide solid evidence that it meets all three requirements of being a rocky body located in a star’s habitable zone that also retains an atmosphere. 寻找宜居行星的天文学家通常会寻找“金发姑娘”式的条件，即那些对生命而言“刚刚好”的环境。LHS 1140 b 是第一颗提供确凿证据的系外行星，它满足了所有三个要求：既是岩石天体，位于恒星的宜居带内，又拥有大气层。

The planet was discovered in 2017, and the new findings are based on observations taken in 2024 and 2025. To detect an atmosphere from 48 light-years away, researchers identified helium leaks emanating from the planet. They provide strong evidence that the planet has an atmosphere and, furthermore, that this atmosphere has existed for at least 3 billion years. The researchers first detected the spectral signature of helium and then used physical models to reconstruct how that gas escapes from the atmosphere. 这颗行星于 2017 年被发现，新的研究结果基于 2024 年和 2025 年的观测数据。为了在 48 光年外探测到大气层，研究人员识别出了从行星上散发出的氦气泄漏。这些证据有力地证明了该行星拥有大气层，而且该大气层至少已经存在了 30 亿年。研究人员首先探测到了氦的光谱特征，然后利用物理模型重建了气体从大气层中逃逸的过程。

While the planet is in a habitable zone, that isn’t proof of life or that its environment resembles that of Earth. In fact, based on the amount of helium escaping, the researchers suggest that the atmosphere is very different from ours. The upper layer, from which the helium is expelled, is only the most obvious one. In the lower layers, there could be heavy gases such as nitrogen, carbon dioxide, or carbon monoxide. 虽然这颗行星位于宜居带，但这并不代表它存在生命，也不意味着其环境与地球相似。事实上，根据氦气逃逸的量，研究人员认为其大气层与我们的大气层截然不同。氦气排出的上层大气只是最明显的部分，在下层大气中，可能存在氮气、二氧化碳或一氧化碳等重气体。

Importantly, the study confirms the viability of the technique the team used for detecting an atmosphere. Moving forward, scientists will need to observe the planet with more powerful instruments to fully characterize its atmosphere and investigate whether it has surface oceans or other features compatible with habitability. 重要的是，这项研究证实了该团队所使用的探测大气层技术的可行性。展望未来，科学家们将需要使用更强大的仪器来观测这颗行星，以全面描述其大气特征，并调查它是否拥有地表海洋或其他与宜居性相关的特征。

“Twenty years ago we wondered whether other terrestrial-type planets even existed,” Robin Wordsworth, a Harvard professor and one of the study’s authors, says in a press release. “Then we learned they’re common, and found some in the habitable zone. The next question was whether any of them had managed to keep an atmosphere. Now, we know at least one has.” “二十年前，我们还在怀疑其他类地行星是否存在，”哈佛大学教授、该研究的作者之一罗宾·沃兹沃斯（Robin Wordsworth）在新闻稿中表示。“后来我们了解到它们很常见，并在宜居带中发现了一些。接下来的问题是，它们中是否有一些能够保留住大气层。现在，我们知道至少有一颗做到了。”