546. Birkas HaChama

Brachos 10:17

This bracha on the renewal of the moon should be recited while standing because one who recites this bracha at the appropriate time is considered as if he greeted the Divine presence. If one did not recite this bracha on the first night, it may be recited until the sixteenth of the month, when the moon is full.

Brachos 10:18

One who sees the sun on the Wednesday morning that is the vernal equinox at the start of the 28-year cycle that begins on Wednesday night recites the bracha that God “performs the work of creation.” The bracha “Who performs the work of creation” is also recited when the moon reaches the beginning of the constellation of Aries at the beginning of the month when it doesn’t point north or south, when the five remaining stars arrive at the beginning of Aries and do not point north or south, and when one sees Aries rise to the eastern corner of the sky.

[Editor’s note: please don’t ask me to explain this last halacha; the astronomy is beyond me.]