The hydrogen 21-cm signal is predicted to be the richest probe of the young Universe, including those eras known as the cosmic Dark Ages, the Cosmic Dawn (when the first star and black hole formed) and the Epoch of Reionization. This signal holds the key to deciphering processes that take place at the early stages of cosmic history. In this opinion piece, we discuss the potential scientific merit of lunar observations of the 21-cm signal and their advantages over more affordable terrestrial efforts. The Moon is a prime location for radio cosmology which will enable precision observations of the low-frequency radio sky. The uniqueness of such observations is that they will provide an unparalleled opportunity to test cosmology and the nature of dark matter using the Dark Ages 21-cm signal. No less enticing is the opportunity to obtain a much clearer picture of the Cosmic Dawn than that currently achievable from the ground, which will allow us to determine the properties of the first stars and black holes.

This article is part of a discussion meeting issue ‘Astronomy from the Moon: the next decades (part 2)’.

氢21厘米信号预计将成为年轻宇宙最丰富的探测器，包括宇宙黑暗时代、宇宙黎明（第一颗恒星和黑洞形成时）和再电离时代。这个信号掌握着破译宇宙历史早期阶段发生的过程的关键。在这篇评论文章中，我们讨论了 21 厘米信号的月球观测的潜在科学价值，以及它们相对于更便宜的地面观测的优势。月球是射电宇宙学的主要地点，可以对低频射电天空进行精确观测。此类观测的独特之处在于，它们将为使用黑暗时代 21 厘米信号测试宇宙学和暗物质的性质提供无与伦比的机会。同样诱人的是有机会获得比目前从地面​​更清晰的宇宙黎明图片，这将使我们能够确定第一批恒星和黑洞的属性。

本文是“月球天文学：未来几十年（第 2 部分）”讨论会议的一部分。