行星 (xíngxīng): planet

Measure Word

一颗行星 kē

Literally 'moving star' -- because planets appear to move against the background of fixed stars.

太阳系有八颗行星。

Tàiyángxì yǒu bā kē xíngxīng.

The solar system has eight planets.

地球是一颗行星。

Dìqiú shì yī kē xíngxīng.

Earth is a planet.

memory

行星 = 'walking star.' The ancient Chinese noticed planets 'walk' across the sky, unlike fixed stars (恒星 héngxīng, 'permanent stars').

行 xíng

星 xīng