Near the end of Kiddush Levana, there is a request that says:
וִיהִי רָצוֹן מִלְּפָנֶיךָ יְיָ אֱלֹהַי וֵאלֹהֵי אֲבוֹתַי לְמַלּאֹת פְּגִימַת הַלְּבָנָה, וְלאֹ יִהְיֶה בָּהּ שׁוּם מִעוּט, וִיהִי אוֹר הַלְּבָנָה כְּאוֹר הַחַמָּה וּכְאוֹר שִׁבְעַת יְמֵי בְרֵאשִׁית, כְּמוֹ שֶׁהָיְתָה קוֹדֶם מִעוּטָהּ, שֶׁנֶּאֱמַר וַיַּעַשֹ אֱלֹהִים אֶת שְׁנֵי הַמְּאֹרֹת הַגְּדֹלִים
My rough translation:
May it be your will, Lord, my G-d and G-d of my fathers to fill the blemish of the moon and there should be no lessening. And the light of the moon shall be as the light of the sun and the light that it had during the 7 days of creation prior to its light being diminished, as is written (Genesis 1:16) "... the two great lights" (implying that both the sun and moon's lights were equal.)
This concept is based on a Midrash cited in Talmud Chulin 60b. In brief, the moon complained to G-d, "Is it possible that there should be two rulers in the sky?" Whereby G-d told the moon to make itself smaller.
- By making this request, aren't we, in a sense, recreating the initial "problem"?
- Of more practical value, reading further in the Talmud page, G-d said that the moon will benefit because Israel will establish its calendar by its cycle. But, if the sun and moon were both in the sky with the same light, would that also, possibly diminish or eliminate its role as being the heavenly body used for Rosh Hodesh? From the Talmud's discussion, it seems as if this role were created because the moon's light was diminished, only.