Celestial bodies

水星
Mercury

The innermost planet, never more than 28° from the Sun.

Visible only in twilight — the hardest planet to catch by eye.

Related terms

Saturn — The ringed planet; separating rings from disc needs about 30×.
Mars — The red planet, about −2.9 magnitude at opposition.
The Moon — Earth's only natural satellite, 3474 km across.
Comet — An icy body that grows a tail near the Sun.