词条 格林尼治标准时区（GMT）
描述: 历史悠久的英国格林威治皇家天文台所在的时区被称为格林威治标准时区，或西欧时区。历史上，格林威治标准时间（GMT）是皇家天文台确定的平均太阳时，并被用作船上携带的海军计时器的参考点。航海家通过使用六分仪或类似装置进行观察来确定当地正午的时间（一天中太阳到达的地平线以上的最高点），并将其与计时器显示的格林威治标准时间进行比较，根据两者的差值确定自己的地理经度。在现代系统中，GMT 时区的时间对应于协调世界时 (UTC)，写为“UTC + 0h”。
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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".
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其他语言版本
- 阿拉伯语: التوقيت المتوسط لجرينتش
- 德语: Greenwich Mean Time (GMT)
- 英语: Greenwich Mean Time Zone (GMT)
- 西班牙语: Zona horaria de Greenwich (GMT)
- 法语: Fuseau horaire de Greenwich (GMT)
- 北印度语: ग्रीनविच मीन टाइम ज़ोन (जीएमटी)
- 意大利语: Fuso orario medio di Greenwich (GMT)
- 马拉地语: ग्रीनविच मीन टाइम झोन (GMT)
- 繁体中文: 格林尼治標準時區（GMT）
相关媒体
Map of de-facto time zones on Earth
图注： Due to the Earth's spherical shape and its rotation around its own axis, local noon – the moment in time when, for an observer at a specific geographic location, the Sun reaches its highest position in the sky varies with longitude. That is why a time coordinate, such as Universal Time (UT or UTC), might be of advantage for specifying moments in time in a unified way. But a global time coordinate will be out of synch with the local day-night rhythm in most locations on Earth. A compromise is to divide Earth into zones each comprising 15 degrees of longitude, and in each zone define time as UTC plus or minus an integer number of hours, with the offset chosen so as to make time match as closely with local time at the middle longitude of the time zone. In practice, political considerations have altered the time zone boundaries somewhat. When a country straddles several time zones, it is not uncommon for the country's government to choose one of those time zones to define the country's official time.
This map, originally created by the CIA and updated by several Wikimedia Commons users, shows the current definitions of the world's time zones. The IAU OAE is not the original author of this map. The designations employed and the presentation of the material on this maps do not imply the expression of any opinion whatsoever on the part of the IAU or the IAU OAE concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
来源： Wikimedia Users UnaitxuGV, Heitordp and others based on a map created by the U.S. Central Intelligence Agency (CIA)
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License: PD 公共领域 图标
