Meaning and Usage
"自転" (じてん) primarily means "rotation" or "spin," referring to an object turning around its own axis. It is often used in scientific contexts, such as describing the Earth's rotation or mechanical parts.
Common Contexts
You will frequently see "自転" in discussions about astronomy (e.g., Earth's rotation), physics, and engineering. It contrasts with "公転" (こうてん), which means "revolution" or "orbiting around another object."
Collocations and Patterns
- 自転する: to rotate or spin
- 自転速度: rotational speed
- 自転軸: axis of rotation
These collocations help specify the nature of the rotation or the object involved.
Register and Usage Notes
"自転" is a formal and technical term, rarely used in casual conversation unless discussing scientific topics. Learners often confuse "自転" with "自転車" (じてんしゃ, bicycle), so be careful to distinguish the two.
Summary
Use "自転" when talking about the rotation of planets, machines, or any object spinning around its own axis. It is a precise term mostly found in academic or technical contexts.