noun
equator
The great circle around the Earth, equidistant from the poles. Used in geography, climate, and everyday contexts.
赤道直下の国々は一年中暑い。
Countries on the equator are hot all year round.
noun
celestial equator
The projection of the Earth's equator onto the celestial sphere. Used in astronomy; often specified as 天の赤道.
See also: 天の赤道
天の赤道は、地球の赤道面を天球に投影したものです。
The celestial equator is the projection of the Earth's equatorial plane onto the celestial sphere.