Planets are expected to conclude their growth through a series of giant impacts: energetic, global events that significantly alter planetary composition and evolution. Computer models and theory have elucidated the diverse outcomes of giant impacts in detail, improving our ability to interpret collision conditions from observations of their remnants. However, many open questions remain, as even the formation of the Moon—a widely suspected giant-impact product for which we have the most information—is still debated. We review giant-impact theory, the diverse nature of giant-impact outcomes, and the governing physical processes. We discuss the importance of computer simulations, informed by experiments, for accurately modeling the impact process. Finally, we outline how the application of probability theory and computational advancements can assist in inferring collision histories from observations, and we identify promising opportunities for advancing giant-impact theory in the future. ▪ Giant impacts exhibit diverse possible outcomes leading to changes in planetary mass, composition, and thermal history depending on the conditions. ▪ Improvements to computer simulation methodologies and new laboratory experiments provide critical insights into the detailed outcomes of giant impacts. ▪ When colliding planets are similar in size, they can merge or escape one another with roughly equal probability, but with different effects on their resulting masses, densities, and orbits. ▪ Different sequences of giant impacts can produce similar planets, encouraging the use of probability theory to evaluate distinct formation hypothesis.

中文翻译：

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巨大撞击在行星形成中的作用


行星预计将通过一系列巨大的影响来结束其生长：充满活力的全球事件会显着改变行星的组成和演化。计算机模型和理论已经详细阐明了巨大撞击的不同结果，提高了我们通过观察其残余物来解释碰撞条件的能力。然而，许多悬而未决的问题仍然存在，甚至月球——一种被广泛怀疑的巨大撞击产物，我们拥有最多的信息——的形成仍然存在争议。我们回顾了大撞击理论、大撞击结果的多样性以及控制物理过程。我们讨论了基于实验的计算机模拟对于准确模拟影响过程的重要性。最后，我们概述了概率论和计算进步的应用如何帮助从观测中推断碰撞历史，并确定了未来推进巨大撞击理论的有希望的机会。 ▪ 巨大的撞击表现出多种可能的结果，导致行星质量、成分和热历史发生变化，具体取决于条件。 ▪ 计算机模拟方法的改进和新的实验室实验为巨大撞击的详细结果提供了重要的见解。 ▪ 当相撞的行星大小相似时，它们可以以大致相同的概率彼此合并或逃逸，但对其产生的质量、密度和轨道产生不同的影响。 ▪ 不同序列的巨大撞击可以产生相似的行星，鼓励使用概率论来评估不同的形成假说。