Siman Tov u'Mazal tov!

(15) For your own sake, therefore, be most careful—since you saw no shape when the LORD your God spoke to you at Horeb out of the fire— (16) not to act wickedly and make for yourselves a sculptured image in any likeness whatever: the form of a man or a woman, (17) the form of any beast on earth, the form of any winged bird that flies in the sky, (18) the form of anything that creeps on the ground, the form of any fish that is in the waters below the earth. (19) And when you look up to the sky and behold the sun and the moon and the stars, the whole heavenly host, you must not be lured into bowing down to them or serving them. These the LORD your God allotted to other peoples everywhere under heaven; (20) but you the LORD took and brought out of Egypt, that iron blast furnace, to be His very own people, as is now the case.

The Sages taught: When the sun is eclipsed it is a bad omen for the entire world. The Gemara tells a parable. To what is this matter comparable? It is comparable to a king of flesh and blood who prepared a feast for his servants and placed a lantern [panas] before them to illuminate the hall. He became angry at them and said to his servant: Take the lantern from before them and seat them in darkness.

It is taught in a baraita that Rabbi Meir says: When the heavenly lights, i.e., the sun and the moon, are eclipsed, it is a bad omen for the enemies of the Jewish people, (which is a euphemism for the Jewish people) because they are experienced in their beatings. This is similar to a teacher who comes to the school with a strap in his hand. Who worries? The child who is accustomed to be beaten each and every day is the one who worries.

The Sages taught in another baraita: When the sun is eclipsed, it is a bad omen for the other nations. When the moon is eclipsed, it is a bad omen for the enemies of the Jewish people (i.e., the Jews). This is due to the fact that the Jewish people calculate their calendar primarily based on the moon, and the other nations calculate based on the sun. ....

The Gemara adds: When the Jewish people perform God’s will, they need not fear any of these omens, as it is stated: “Thus says the Lord: Learn not the way of the nations, and be not dismayed at the signs of Heaven; for the nations are dismayed at them” (Jeremiah 10:2). The nations will be dismayed, but the Jewish people will not be dismayed, provided they do not follow the ways of the nations.

It was stated that Rabbi Ḥanina says: A constellation makes one wise and a constellation makes one wealthy, and there is a constellation for the Jewish people that influences them. Rabbi Yoḥanan said: There is no constellation for the Jewish people. And Rabbi Yoḥanan follows his own reasoning, as Rabbi Yoḥanan said: From where is it derived that there is no constellation for the Jewish people? As it is stated: “Thus said the Lord: Learn not the way of the nations, and be not dismayed at the signs of heaven; for the nations are dismayed at them” (Jeremiah 10:2). The nations will be dismayed by them, but not the Jewish people.

Maimonides (12th cent., Morocco and Egypt)

Who is a soothsayer? They that point at times, saying astrologically: "That day is a good one, that day is a bad one; that day is fit to do that particular work, but that year, or that month, is bad for that particular thing.¹¹Ibid. G.

It is forbidden to be a soothsayer, though no act be committed, save to make known the lies to such fools who believe them to be true speech of the wise. Moreover, he who does aught because of the signs of astrology, and times to do his work or go on his mission on the very time, set by the heaven-gazers, even he is striped, for it is said: "Nor soothsay" (Lev. 126).¹²Here a distinction must be made between an observer of times and an enchanter. See supra, Par. 7. G. Likewise, one who deludes the eyes by performing some act alleging it to be wonderful, but in truth makes no performance at all, even he is included among observers of time, and his punishment is stripes.

1. That one should not perform sorcery, soothsaying, or divination.

One should not consult with stargazers or those who cast lots. Rema: Because as it says you shall be simple with the Lord your God. And all the more so it is forbidden to consult with magicians, diviners, and sorcerers.

2. We have the custom not to begin something on Monday or Wednesday and women only marry when the moon is waxing (the first half of the month). Rema: And we also have the practice to begin studying on Rosh Chodesh, because even though it is not divination, there is a sign. What a person knows is against the stars he will not do, and we do not rely upon miracles. Rather, we don't deeply investigate this (astrology) because of "you shall be simple," as was explained.