φάσις (<φαίνω)

There are two forms of appearance of stars:
1) the appearance during the night or in twilight, i.e. the rising of the star above the local horizon or the sky getting dark enough for the star to become visible.

2) the appearance during the year: While the Earth orbits the Sun, it appears to an observer on Earth as if the Sun travels in a circle in the sky: each month, the Sun stands in front of other stars and constellations in the zodiac. The stars "behind" the Sun are invisible in the night sky. While the apparent Sun travels further, the stars that had been behind it in the previous month, reappear in the (morning) sky.