Glossary term: 逃逸速度
Description: 逃逸速度是物体要永久逃离天体引力场所需的最小速度，在物理上它是一个标量，因此更准确的说法是“逃逸速率”，但“逃逸速度”这一术语更为常用。最简单的情况是具有球对称的天体，这对描述恒星和行星来说是一个很好的近似。在这种情况下，质量为m的天体，其中心距离为r的位置的逃逸速度可由公式√(2Gm/r)给出，其中G为引力常数。对于球形天体而言，其表面至中心的距离即为半径，因此逃逸速度取决于天体的半径和质量。例如，太阳表面的逃逸速度为617.5公里/秒（km/s），地球为11.2 km/s，而月球为2.4 km/s，这意味着在月球上物体摆脱其引力需要达到的速度比在地球上更低。
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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher The translation of this term and its definition is still awaiting approval
The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".
