(condensed from Ein Ayah, Berachot 9:163)

Gemara: One who sees the Great Sea recites the blessing … when he sees it periodically. How long a break constitutes periodically? Rami bar Abba says in the name of Rabbi Yitzchak: thirty days.

Ein Ayah: The reason for the time period of thirty days is that we learn wisdom from the heavenly bodies, as the pasuk says: “Lift up your eyes to the heavens and see who created these” (Yeshaya 40:26). Of all the heavenly bodies, the one that is closest and most linked to our own planet of Earth is the Moon. That is why the Jewish people count the passage of time based on the orbit of the Moon. The Moon’s creation also has special significance for the needs of our planet. Part of its effect has to do with the fact that the amount of time of the Moon’s orbit is connected to renewed feelings, which makes it appropriate to recite a new beracha based on it.

For this reason, also, new Moons are a time of atonement for Israel, as it is a time when a new spirit takes the place of an old spirit. At that time, it is possible to create a ‘new heart’ in matters of wisdom and fear of Hashem.