大地震帶來大迷思! 大地震會造成地球自轉軸偏移嗎?
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Alan Lin
Mar 21, 2011, 1:27:16 PM3/21/11
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最近許多報導指出日本311大地震，造成地球自轉變快，地軸偏移。
這個地軸是指地球自轉軸嗎?
美國太空總署(NASA)的地球物理學家Richard Gross這樣說：
The Earth rotates around its rotation axis, but its mass is balanced about a different axis, the figure axis. Because these axes are different, the Earth wobbles as it rotates.(Beitler, 2010, 摘錄自NASA網頁)
地球繞著它的自轉軸旋轉，但是它的質量卻是對另一個不同的軸--質心軸(註1)平衡。因為這兩個軸不同，所以地球自轉時會晃動。
我們再來看看美國太空總署(NASA)的新聞稿怎麼說?
The calculations also show the Japan quake should have shifted the position of Earth's figure axis (the axis about which Earth's mass is balanced) by about 17 centimeters (6.5 inches), towards 133 degrees east longitude. Earth's figure axis should not be confused with its north-south axis; they are offset by about 10 meters (about 33 feet). This shift in Earth's figure axis will cause Earth to wobble a bit differently as it rotates, but it will not cause a shift of Earth's axis in space—only external forces such as the gravitational attraction of the sun, moon and planets can do that.(NASA, 2011-3-14)
計算同時顯示，日本地震應該已經使得地球質心軸(地球質量對此軸平衡)的位置向東經133度偏移了大約17公分。地球質心軸不應該和地球南北軸(即地球在太空中的自轉軸，註2)混淆，兩者大約相距10公尺。這次地球質心軸的偏移將使得地球自轉時的晃動(註3)和以往有一點點不同，但是它不會造成太空中的地軸變動(指自轉軸指向的變動)——只有外力(如太陽、月亮或行星的萬有引力)才能造成這種變動。
這個地軸是指地球自轉軸嗎?
美國太空總署(NASA)的地球物理學家Richard Gross這樣說：
The Earth rotates around its rotation axis, but its mass is balanced about a different axis, the figure axis. Because these axes are different, the Earth wobbles as it rotates.(Beitler, 2010, 摘錄自NASA網頁)
地球繞著它的自轉軸旋轉，但是它的質量卻是對另一個不同的軸--質心軸(註1)平衡。因為這兩個軸不同，所以地球自轉時會晃動。
我們再來看看美國太空總署(NASA)的新聞稿怎麼說?
The calculations also show the Japan quake should have shifted the position of Earth's figure axis (the axis about which Earth's mass is balanced) by about 17 centimeters (6.5 inches), towards 133 degrees east longitude. Earth's figure axis should not be confused with its north-south axis; they are offset by about 10 meters (about 33 feet). This shift in Earth's figure axis will cause Earth to wobble a bit differently as it rotates, but it will not cause a shift of Earth's axis in space—only external forces such as the gravitational attraction of the sun, moon and planets can do that.(NASA, 2011-3-14)
計算同時顯示，日本地震應該已經使得地球質心軸(地球質量對此軸平衡)的位置向東經133度偏移了大約17公分。地球質心軸不應該和地球南北軸(即地球在太空中的自轉軸，註2)混淆，兩者大約相距10公尺。這次地球質心軸的偏移將使得地球自轉時的晃動(註3)和以往有一點點不同，但是它不會造成太空中的地軸變動(指自轉軸指向的變動)——只有外力(如太陽、月亮或行星的萬有引力)才能造成這種變動。
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