Parshat Bo contains the first Mitzvah ever to grace the collective ears of Bnei Yisrael, namely the Mitzvah of Rosh Chodesh. Hashem tells His people, “HaChodesh HaZeh Lachem Rosh Chodashim,” “This month is for you the first of the months” (12:2), and commands them to declare a new month for every lunar cycle. Leaving aside the much-discussed question of why the Torah does not start with this first Mitzvah, another readily apparent question falls into place: why follow the moon? Isn’t the sun the most dominant and prominent celestial object, supplying warmth and playing a vital role for all human survival?
In fact, many Meforshim offer explanations for this perplexing difficulty. In one of the most famous interpretations, the Midrash offers an amazing answer, saying that the lunar cycle represents the history and collective personality of Bnei Yisrael. The Midrash observes that the moon goes through an interesting cycle every month. It becomes something magnificent and complete during mid-month, but then slowly edges its way to nothingness – and just when it seems it is gone, the moon pops out once more for a new cycle around. So, too, Am Yisrael reach their peak at certain points in history, gaining the awe and respect of the entire world. But then catastrophe strikes, and Bnei Yisrael are slowly reduced to ashes, turmoil, and despair, leaving their enemies confident of a final victory. However, just when all hope is gone and the going gets tough, the Jewish people miraculously rise up and conquer their foes, and regain power once again.
The Sefat Emet explains that the choice of the moon over the sun is based on the times of appearance of each extraterrestrial body. Just like the moon, Bnei Yisrael always exist, are present during both day and night, and illuminate the world even during its darkest hours. Conversely, the various Nochri nations, like the sun, are around only for select times and cannot support the needs of the entire world for twenty-four hours.
The Rim offers an extremely interesting answer, citing the verse from Kohelet (1:9) that states, “Ein Kol Chadash Tachat HaShamesh,” “There is nothing new under the sun.” The Rim notes that this is a perfect reason to choose the moon over the sun. Like the sun itself, the entire physical world and nature under the sun rarely make any substantial advancements or accomplishments. Therefore, in order to represent the “LeMaalah-Min-HaTeva” nation of Am Yisrael, Hashem chose the moon which, unlike the sun, does grow and make changes. Only the moon would be able to facilitate the great wonders and innovations which would occur to Bnei Yisrael.