Book of Astronomy

Section Seven: On the Eastern Rising and Western Setting of the Five Planets

When the five planets five planets original: 五星 (wǔxīng); the five planets visible to the naked eye: Saturn, Jupiter, Mars, Venus, and Mercury. rise before the Sun Sun original: 太陽 (Tàiyáng)., this is called Eastern Rising This refers to a planet's "Oriental" position, appearing in the dawn sky before sunrise.. When they set after the Sun, this is called Western Setting This refers to an "Occidental" position, remaining visible in the twilight after sunset..

At the time of Eastern Rising, each planet has its own specific degree degree original: 度數 (dùshù); a unit of measurement for the angular distance (elongation) between the planet and the Sun. of separation. For the three planets Saturn, Jupiter, and Mars, the distance from the Sun does not exceed sixty degrees. For Venus, the distance from the Sun does not exceed forty-five degrees. For Mercury, the distance from the Sun does not exceed twenty-five degrees.

The furthest distance of the two planets Venus and Mercury As "inferior planets" whose orbits are inside Earth's, Venus and Mercury never appear very far from the Sun. from the Sun never exceeds these specific degree counts.

The same degree rules apply when the five planets set after the Sun. However, if the three planets Saturn, Jupiter, and Mars are more than sixty degrees away from the Sun, they are no longer counted within the classification of Eastern Rising or Western Setting Because these "superior planets" can reach "Opposition" (180 degrees from the Sun), they spend much of their cycle outside the near-solar windows of rising and setting described here..