惑星（わくせい、wakusei）
- planet

The Japanese word 惑星 （わくせい） means "planet" in English. It refers to a celestial body that orbits a star, such as the Sun, and is massive enough to be rounded by its own gravity, and has cleared its neighborhood of other objects. ⚫︎ It's a general term used in astronomy and everyday conversation when discussing celestial bodies. ⚫︎ The word covers all planets in our solar system and also, potentially, planets orbiting other stars (exoplanets).

⚫︎ 太陽系の惑星 Translation: Solar system planets. ⚫︎ 地球は惑星です。 Translation: Earth is a planet. ⚫︎ 火星は赤い惑星です。 Translation: Mars is a red planet.

⚫︎ Use 惑星 （わくせい） when discussing planets in a scientific context. ⚫︎ It's also suitable for general conversations about space, astronomy, and the solar system. ⚫︎ It is a formal and accurate word, used to describe the astronomical concept of a planet.

⚫︎ The word 惑星 is typically written in kanji. ⚫︎ The reading, わくせい, is written in hiragana. ⚫︎ There are no other common ways to write this word, nor are there variations in the okurigana.

There aren't direct synonyms for 惑星 that carry the same astronomical meaning, but here are some related terms: ⚫︎ 星（ほし）: Star or celestial body (broader meaning) ⚫︎ 太陽系の天体（たいようけいのてんたい): Celestial bodies in the solar system. ⚫︎ 天体（てんたい）: Celestial body

There is no direct antonym for 惑星, but we can consider: ⚫︎ 恒星（こうせい): A star (e.g., the Sun)

新しい惑星が発見されました。 ・Translation: A new planet has been discovered. ・Explanation: This sentence describes the discovery of a new planet.

惑星の表面は多様な地形を持っています。 ・Translation: The surface of the planet has diverse terrains. ・Explanation: This sentence discusses the surface features of a planet.

The word 惑星 is a compound word derived from: ⚫︎ 惑（わく）: "to be perplexed," "to be confused" or "to wander" (in old times, planets were thought to "wander" across the sky compared to the fixed stars) ⚫︎ 星（せい）: "star" This combination describes the “wandering stars” which is the literal translation of the Kanji.