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  • General

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  • 地球自转

    Four panels depicting the Sun's movement from sunrise to sunset and moonrise.
     

    How do you know Earth rotates?
    ::你怎么知道地球旋转?

    Something amazing happens every  day  (unless you live very far north or very far south)! The amazing thing is that the   rises in the east. It also sets in the west. We know that the Sun doesn't actually move around Earth. What causes the Sun to rise and set is that Earth rotates on its  axis . This  rotation  creates day and night.
    ::每天都有惊人的事情发生(除非你住在很远的北面或很远的南面)! 令人惊奇的是, 东部的上升也发生在西面。 同时它也位于西面。 我们知道太阳实际上并不环绕地球。 太阳之所以升起和设定,是因为地球在其轴上旋转。 这种旋转会创造昼夜。

    Earth's Axis of Rotation
    ::地球的动力轴

    Imagine a line passing through the center of Earth. The line exits the  planet  at the top and at the bottom. The point at the top is the North Pole. The point at the bottom is the South Pole. This imaginary line is called an  axis . The points are the north and south geographic poles. The geographic poles are different from the magnetic poles, and they are in slightly different places on the planet.
    ::想象一下穿过地球中心的一条线。 这条线从地球的顶部和底部离开。 顶部的点是北极。 底部的点是南极。 这个假想的线称为轴。 点是北面和南面的地理极。 地理极与磁极不同, 它们位于这个星球上稍有不同的地方 。

    Earth's axis, celestial equator, ecliptic, and rotation direction.
     
    Earth rotates on an axis, an imaginary line that goes from the North (celestial) Pole to the South (celestial) Pole.

    Note that Earth's  axis of rotation  is tilted. The axis is not perpendicular to the plane of the ecliptic. This plane is the one that  solar system  bodies are mostly lined up in.
    ::请注意, 地球的旋转轴是倾斜的。 轴与日圆平面并不垂直。 此平面是太阳系物体大多排成的平面 。

    Earth spins around its axis, just as a top spins around its spindle. This spinning movement is called  rotation . The axis is Earth's  axis of rotation . Earth rotates on its axis once every 24 hours.
    ::地球围绕其轴旋转, 正如其脊柱上旋转一样。 这种旋转运动被称为旋转。 轴是地球的旋转轴。 地球每24小时在其轴上旋转一次 。

    Day-Night Cycle
    ::日夜周期

    To an observer looking down at the North Pole, Earth appears to rotate counterclockwise. From nearly all points on Earth, the Sun appears to move across the sky from east to west each day. Of course, the Sun is not moving from east to west at all; Earth is rotating. The Moon and  stars  also seem to rise in the east and set in the west.
    ::观察北极的观察者认为,地球似乎逆时针旋转。从地球上几乎所有的点看,太阳每天从东向西飞过天空。当然,太阳从东向西飞过天空;地球是旋转的。月亮和恒星也似乎在东向上升,而位于西向。

    Earth’s rotation means that there is a cycle of daylight and darkness approximately every 24 hours. This is the length of a day. Different places experience sunset and sunrise at different times, and the amount of daylight and darkness also differs by  .
    ::地球的旋转意味着日光和黑暗的循环大约每24小时就有一个周期。 这就是一天的长度。 不同的地方在不同的时间都经历日落和日出,白天和黑暗的数量也各不相同。

    Summary
    ::摘要

    • Sun, Moon, and stars appear to travel from east to west each day.
      ::太阳,月亮,星星 似乎每天都从东向西飞来
    • Earth rotates on its axis every 24 hours.
      ::地球每24小时在其轴上旋转一次。
    • Earth's rotation causes the day-night cycle.
      ::地球的旋转导致日夜循环

    Review
    ::回顾

    1. What is an axis of rotation? Where is Earth's axis of rotation?
      ::什么是旋转轴?地球旋转轴在哪里?
    1. Why do the Sun, Moon, and stars appear to rise in the east and set in the west?
      ::为什么太阳、月亮和恒星 似乎在东边升起,在西边落下?
    1. What is the length of a day-night cycle? Is it the same everywhere on Earth?
      ::日间循环的长度是多少?地球上任何地方都是一样的吗?

    Explore More
    ::探索更多

    Use the resources below to answer the questions that follow.
    ::利用以下资源回答以下问题。

     

     

    1. Why does the Earth spin?
      ::为什么地球在旋转?
    1. Why has the Earth's spin slowed?
      ::为什么地球的旋转速度放慢?
    1. What will eventually happen to the Moon?
      ::月球最终会怎样?

     

    1. How long does it take for the Earth to complete a revolution based on the Siderial method of measurement?
      ::地球需要多久才能完成以西天线测量方法为基础的革命?
    1. In what direction is the Earth rotating?
      ::地球在什么方向旋转?