Uranus and Neptune form a distinct class of planets in our Solar System. Given this fact, and ubiquity of similar-mass planets in other planetary systems, it is essential to understand their interior structure and composition. However, there are more open questions regarding these planets than answers. In this review, we concentrate on the things we do not know about the interiors of Uranus and Neptune with a focus on why the planets may be different, rather than the same. We next summarize the knowledge about the planets’ internal structure and evolution. Finally, we identify the topics that should be investigated further on the theoretical front as well as required observations from space missions. This article is part of a discussion meeting issue ‘Future exploration of ice giant systems’.

中文翻译：

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天王星和海王星的内部：目前的理解和开放的问题

天王星和海王星在我们的太阳系中形成了一类独特的行星。鉴于这一事实，以及类似质量行星在其他行星系统中的普遍存在，了解它们的内部结构和组成至关重要。然而，关于这些行星的悬而未决的问题多于答案。在这篇评论中，我们专注于我们不知道的关于天王星和海王星内部的事情，重点是为什么行星可能不同，而不是相同。接下来我们总结一下行星内部结构和演化的知识。最后，我们确定了应该在理论前沿进一步研究的主题以及太空任务所需的观察。本文是讨论会问题“冰巨星系统的未来探索”的一部分。