precession
precession — 名詞
1. a gradual change in the direction of a planet's or star's spin axis as the body
歲差
天體自轉軸的緩慢偏移
a gradual change in the direction of a planet's or star's spin axis as the body travels through space around another body
The textbook explains how Earth's precession changes the night sky over centuries.
那本教科書說明了地球的歲差如何在幾個世紀中改變夜空。
Earth's precession in astronomy
Because of precession, the pole star is not always the same star.
因為有歲差，北極星並不會一直是同一顆星。
A museum video shows precession as the planet's axis slowly shifts.
博物館影片用行星自轉軸慢慢偏移來展示歲差。
Scientists measure precession to predict where the equinox points will move.
科學家會測量歲差，好預測分點的位置會往哪裡移動。
- axial drift
a plain-language description, not the fixed scientific term
- wobble
broader and less precise than the astronomical sense
用法筆記
Used for long-term changes in the axes of planets or stars. Distinguish from sense 2, which is about the visible wobbling motion of a spinning object such as a top or gyroscope.
2. a movement where a spinning object's line of rotation slowly circles another lin
進動
旋轉軸繞另一線慢慢轉
a movement where a spinning object's line of rotation slowly circles another line, so the object appears to wobble around a cone
When the toy top slowed down, its precession became easy to see.
當玩具陀螺慢下來時，它的進動就變得很容易看見。
precession in a spinning top
The lab camera recorded the wheel's precession as it spun on its stand.
實驗室的攝影機記錄下那個輪子在支架上旋轉時的進動。
Kemi drew a cone to show the precession of the spinning disk.
Kemi 畫了一個圓錐，來說明旋轉圓盤的進動。
Students noticed precession when the gyroscope's axis began to circle.
當陀螺儀的軸開始繞圈時，學生注意到了進動。
用法筆記
This sense is used for tops, gyroscopes, wheels, and other spinning objects. Distinguish from sense 1, which refers to the slow change in a planet's or star's axis over time.