惑星

1. Origins, structure, and basic meaning

• Structure: 惑星 is read as わくせい and is a noun for a planet, a celestial body that travels around a star.
• Basic usage: A model appears in 惑星の模型, while an unknown one appears in 未知の惑星.

2. Common pitfalls and similar expressions

• Category and individual body
  • It can name the astronomical category or refer to one particular planet in context.
• Difference from 恒星
  • 恒星 is a star that produces its own light; 惑星 is a body that travels around such a star.