Shulchan Arukh Orach Chayim · Siman 229

English

One who sees the rainbow says, "Blessed are you, God our Lord, king of the world, who remembers the covenant, who is faithful to his covenant, and who fulfills his word." And it is forbidden to look upon it further.

English

One who sees the sun at its tekufah [cycle/season]—which occurs every 28 years, and the tekufah begins at the start of the night preceding Wednesday—when one sees it [the sun] on Wednesday morning, says: "Blessed... Who makes the works of creation." And similarly, one also makes this blessing when seeing the moon in its purity, the stars in their watches, and the constellations in their appointed times. This refers to when the moon returns to the beginning of the constellation Aries at the start of the [lunar] month and is not inclined either northward or southward; and similarly when each of the five [visible] planets returns to the beginning of the constellation Aries and is not inclined either northward or southward; and similarly, any time one sees the constellation Aries rising from the eastern edge [of the horizon].