In Mandarin Chinese, 星 (Pinyin: xīng 🔊) means “star”, broadly speaking: it could be any heavenly body, celebrity, or a star shape. “Star” in a purely astronomical sense is 星星 (xīngxing) — not to be confused with 行星 (xíngxīng), “planet”.
You’d think that the Chinese could have chosen something like ★ to represent a star, but no. The original form of 星 was 曐, which is made of 晶 (jīng) “sparkling” on top of now-familiar 生 (shēng) “to give birth”, “to grow”, etc. In its turn, 晶 consists of three radicals 日 (rì), “sun”. In 星, only one sun is left, but you get the picture. Many historical forms of this character look surprisingly similar to the Western astrological or astronomical symbols.
According to Wǔ Xíng, the five elements correspond to the five visible planets (and vice versa) as follows:
- 水 + 星 = 水星 (Shuǐxīng) “water star” = Mercury
- 金 + 星 = 金星 (Jīnxīng) “metal star” = Venus
- 火 + 星 = 火星 (Huǒxīng) “fire star” = Mars
- 木 + 星 = 木星 (Mùxīng) “wood star” = Jupiter
- 土 + 星 = 土星 (Tǔxīng) “earth star” = Saturn