The Earth-Moon system has always been perplexing.

地月系统一直令人困惑。

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The wisdom of the day was derived from Ptolemy, an astronomer of the second century, whose elaborate system of the sky put Earth at the center of all heavenly motions.

当时的智慧来自于二世纪的天文学家托勒密，他的复杂天空体系把地球置于所有天体运动的中心。

youdao

The wisdom of the day was derived from Ptolemy, an astronomer of the second century, whose elaborate system of the sky put Earth at the center of all heavenly motions.

当时的智慧来自于二世纪的天文学家托勒密，他的复杂天空体系把地球置于所有天体运动的中心。

youdao

But last month,a computer programmer from Australia made an exciting discovery of an unusual event in Earth's solar system.

VOA: special.2009.08.25

The Earth seems to be a pretty good inertial system, because on the ground, you leave something, it stays there.

地球看上去是个不错的惯性系,因为什么东西放在地上,都会保持静止

耶鲁公开课 - 基础物理课程节选

That made it very beautiful and there's no way in God's earth that we could replicate that to the Western system of musical notation.

那使得它十分美丽,我们却没有任何办法,用西方的乐谱方法,再现这样的音乐

耶鲁公开课 - 聆听音乐课程节选

The loss of observations of key Earth system components and processes will weaken the ability to understand and forecast changes arising from interactions and feedbacks within the Earth system and limit the data and information available to users and decision makers.

FORBES: Losing NASA's Eyes in the Sky

"The proposed road could lead to the collapse of the largest remaining migratory system on Earth - a system that drives Tanzania's tourism trade and supports thousands of people, " the appeal said.

BBC: Scientists urge rethink of Serengeti road plans

The migration of the wildebeest was the "largest remaining migratory system on Earth", they said.

BBC: Scientists urge rethink of Serengeti road plans