Encyclopedia of Solid Earth Geophysics
Encyclopedia of Solid Earth Geophysics
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DOI：
10.1007/978-3-030-10475-7
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发表时间：
2020
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影响因子：
--
通讯作者：
D. James
中科院分区：
文献类型：
--
作者：
D. James
背景地球的形状一直被推测-历史记载的水手记录，他们担心如果他们航行太远，会从地球的边缘掉下来。关于地球形状的早期观点认为地球是平的，而天空是一个横跨在地球上的物理圆顶。球形地球的两个早期论点是，月食被视为圆形阴影，只能由球形地球引起，而极星星在天空中的位置越低，越南。荷马（公元前世纪）所主张的扁平圆盘后来让位于毕达哥拉斯（公元前6世纪）所提出的球形物体--100年后亚里士多德（公元前384-322年）支持了这一观点。根据古老的文献记载，埃拉托色尼（约公元前284-192年）于公元前250年左右在埃及进行了第一次大地测量实验。埃拉托色尼注意到夏至日的太阳在Syene（接近今天的Assouan）是在天顶，而它的天顶距离在亚历山大（大约在同一子午线上）被记录为7 12 0。由于托勒密·索特（Ptolemy Soter，约公元前360-283年）的地籍测量，他知道了Syene和亚历山大之间的几何距离，他推断地球周长为40，500公里。后来喜帕恰斯（在公元前世纪）建议使用纬度和纬度的制图（在协议其希腊词源）。伟大的印度数学家Aryabhatta（公元476-550年）将地球描述为球形并绕轴旋转。他估计了地球的周长，精确到今天测量的1%。中世纪波斯大地测量学家阿布·雷汉·比鲁尼（Abu Rayhan Biruni，公元973-1048年）因其在大地测量领域的重大贡献而被认为是“大地测量之父”。他解决了基于球面三角学的复杂测地线方程，以精确计算地球的周长和半径，这非常接近现代值。地球的形状是各种运动所产生的力的综合结果，在重力的影响下，旋转是最强的，包括时空变化以及水平构造力（更多信息请参阅本卷的“大地测量学，物理”和“重力，全球模型”）。
BackgroundThe shape of the Earth has always been speculated upon–historical accounts of sailors record that they feared falling off the edge of the Earth if they sailed too far. Early ideas about the figure of the Earth held the Earth to be flat and the heavens a physical dome spanning over it. Two early arguments for a spherical Earth were that lunar eclipses were seen as circular shadows which could only be caused by a spherical Earth, and that the pole star is seen lower in the sky as one travels south. The flat disc advocated by Homer (in the ninth century BC) later gave way to the spherical body postulated by Pythagoras (in the sixth century BC)–an idea supported one hundred years later by Aristotle (384–322 BC). According to old texts, the first geodetic experiment took place around250 BC by Eratosthenes (about 284–192 BC) in Egypt. Eratosthenes noted that the Sun on the summer solstice day at Syene (close today to Assouan) was at the zenith while its zenithal distance at Alexandria (approximately on the same meridian) was recorded as 7 12 0. By knowing the geometrical distance between Syene and Alexandria thanks to a cadastre performed by Ptolemy Soter (about 360–283 BC), he deduced, the length of the terrestrial circumference as 40,500 km. Later Hipparchus (in the second century BC) recommended the use of latitudes and longitudes for cartography (in agreement with its Greek etymology). The great Indian mathematician Aryabhatta (476–550 AD) described the Earth as being spherical and rotating on its axis. He estimated the circumference of the Earth, accurate to 1% of today’s measurement. The medieval Persian geodesist Abu Rayhan Biruni (973–1048 AD) is sometimes regarded as the “father of geodesy” for his significant contributions to the field. He solved complex geodesic equations based on spherical trigonometry in order to accurately compute the Earth’s circumference and radius, which are very close to modern values. The shape of the Earth is the combined result of the forces due to the various motions, rotation being the strongest under the influence of gravity including its spatiotemporal variations as well as horizontal tectonic forces (more in▶“Geodesy, Physical” and▶“Gravity, Global Models” in this volume).