Description: 轨道周期是一个天体绕另一个天体运行一圈所需的时间。换一种说法，它是一个天体在其轨道上返回到同一点所需的时间。这可能是一颗行星绕着一颗中心恒星运行（例如地球绕着太阳运行）；可能是一颗卫星绕着一颗行星运行；可能是一颗恒星、一群恒星或星云绕着一个星系的中心运行；也可能是两颗恒星（双星系统）绕着它们共同的质量中心运行。

Related Terms:

• 双星
• 万有引力
• 开普勒定律
• 轨道
• 太阳风

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".