天平动

天平動

tiānpíngdòng

noun

Meanings

1 libration (astronomy: the slight rocking motion of the Moon as seen from Earth, which lets us glimpse a bit more than half its surface over time)

Characters

level / balance

to move / motion

Examples

由于天平动，我们可以观测到月球约59%的表面。

Yóuyú tiānpíngdòng, wǒmen kěyǐ guāncè dào yuèqiú yuē 59% de biǎomiàn.

Because of libration, we can observe roughly 59% of the Moon's surface.

天平动是月球轨道椭圆性造成的现象。

Tiānpíngdòng shì yuèqiú guǐdào tuǒyuánxìng zàochéng de xiànxiàng.

Libration is a phenomenon caused by the ellipticity of the Moon's orbit.

Tips

memory

天平 (tiānpíng) is a balance scale, and 动 (dòng) is 'movement' — 'balance-scale rocking', exactly the to-and-fro tilt the Moon shows. The Latin libration also comes from libra 'balance scale', so the metaphor matches across languages.

Stroke Order

天 tiān

平 píng

动 dòng