古行星能夠用肉眼看到七個天體之一，水星、金星、月球、太陽、火星、木星和土星，古代天文學家認為它在天空中圍繞著固定的地球和固定的恆星中旋轉
One of the seven celestial bodies, Mercury, Venus, the moon, the sun, Mars, Jupiter, and Saturn, visible to the naked eye and thought by ancient astronomers to revolve in the heavens about a fixed Earth and among fixed stars.
水星上面過於乾燥，並且缺乏氧氣。
Mercury is too dry and poor in oxygen.
內行星明亮的半圓月球、水星或金星其一半被照亮的現象
The phase of the moon, Mercury, or Venus when half of the disk is illuminated.
我們太陽系的行星有水星、金星、地球、火星、木星、土星、天王星和海王星。
The planets of our solar system are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
