衛星

1. Origins, structure, and basic meaning

• Structure: 衛星(えいせい) is a noun for a celestial body or artificial object orbiting a planet.
• Basic usage: The examples include both a human-made 人工衛星 and a 天然の衛星, such as the moon.

2. Common pitfalls and similar expressions

• What 人工 specifies
  • 人工 in 人工衛星 specifies that it was made by people. Do not restrict 衛星 alone to artificial satellites in every context.
• The homophone 衛生
  • 衛生(えいせい) concerns hygiene and health protection. Following nouns help distinguish the two identical readings, as in 衛星画像 and 衛生管理.