Glossary term: 天底
Description: 天底定义为观测者正下方的一点。这个点是随观察者位置的变化而变化的。对位于伦敦的观测者来说，他的天底与位于北京或开普敦的观测者的天底是不同的。若用角度来度量，则天底与地平线成90度。与天底相对的一点称为天顶。
Related Terms:
See this term in other languages
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".
