Gemara

(Mishnah): R. Gamliel had forms of the moon on a tablet on the wall. He would ask witnesses about the new moon which forms they saw.

Question: "Lo Sa'asun Iti" - do not make things in the form of things that serve Me!

Answer (Abaye): This forbids a form with the four faces of a Chayah (a type of angel).

Question (Beraisa): "Asher ba'Shomayim" includes the sun, moon, stars and constellations. "Mi'Ma'al" includes ministering angels.

Answer: That forbids worshipping them. (One may make their forms.)

Question (Beraisa): "Lo Sa'asun Iti" - do not make forms of those who serve Me above, such as the sun, moon, stars and constellations.

Answer #1: A Nochri made them for R. Gamliel.

Question: A Nochri made Rav Yehudah's signet ring, and Shmuel told him to damage its form!

Answer: This was to avoid suspicion, for it had a protruding form;

Beraisa: If a signet ring has a protruding form, one may not wear it, but one may sign with it (for it makes a recessed form). If its form is recessed, one may wear it, but not sign with it (it makes a protruding form).

Question: We are not concerned lest people suspect Yisraelim of idolatry! A statue was placed in the Beis ha'Keneses of Shaf v'Yasiv. Shmuel's father and Levi prayed there. They were not concerned for suspicion!

Answer: People will suspect an individual, but not a large group.

Question: If so, R. Gamliel should have been concerned!

Answer #1: He was the Nasi and people constantly came to him, so he is considered like a large group.

Answer #2: R. Gamliel's images were of Perakim.

Answer #2 (to Question 7): For the sake of learning, such images are allowed.

Beraisa: "Lo Silmad La'asos (do not learn witchcraft to use it)", but you may learn in order to understand and give Halachic rulings.

Rishonim

Rif: A Beraisa forbids forms of Hash-m's servants above, such as the sun, moon, stars and constellations. It was permitted for R. Gamliel, for his intent was only to understand and give Halachic rulings.

Ran (DH Tanan): R. Gamliel's images were of Perakim, i.e. they came in parts. He assembled them only when interrogating witnesses. They were not visible at other times, so there was no suspicion.

Answer (Ran citing Maharam me'Rotenbork): There are two verses. It says "Lo Sa'asun Iti Elohei Chesef vEilohei Zahav Lo Sa'asu Lachem". The Reisha, "Lo Sa'asun ", forbids you to make, but allows images made by others. It refers to the end of the previous verse, "Ki Min ha'Shomayim Dibarti Imachem", i.e. lower servants. The end of our verse, "Iti...Lo Sa'asu" refers to what is closer to Hash-m, i.e. upper servants. "Lachem" forbids even those made by others.

Question (Ran): The Gemara asked, even though others made Rav Yehudah's ring, Shmuel told him to deface it. Presumably it was a human image. If so, it does not matter who made it!

Answer (Ran): We must say that it had the image of a lower servant. The Rif and Rambam did not specify; the Rambam does not permit lower servants made by others. They must explain that in the conclusion images may be made for the sake of learning or ruling, so Yisraelim made R. Gamliel's images, and we do not distinguish upper from lower servants. However, if so we retract from Abaye's Drashah that distinguishes. It is difficult why the Gemara did not say 'Ela'.

Ran: A Beraisa distinguishes between rings with recessed and protruding images. Some say that it does not discuss images of Hash-m's servants. Whatever the Torah forbids making is forbidden in every case. Rather, it discusses other forms. Chachamim forbade protruding forms due to suspicion. Similarly, the Torah permits lower servants made by others, but Chachamim forbid protruding forms due to suspicion. The same applies to all other forms.

Ran: Others say that whatever the Torah forbids is forbidden only if it protrudes. The Beraisa that discusses different rings refers to forbidden images. It seems that the previous opinion is correct, for Shmuel told Rav Yehudah to deface his ring even though others made it. This was due to suspicion, and regarding R. Gamliel there was no suspicion. The Beraisa about rings shows that sometimes, we forbid permitted images due to suspicion. However, according to the latter opinion, the Beraisa is no support. Perhaps it forbids only protruding images of what the Torah forbids! It is a poor answer to say that we infer from the Heter to stamp with a protruding ring that the Isur is only mid'Rabanan, for otherwise we would forbid mid'Rabanan. The Ramban says that we forbid due to suspicion only on honorable things. It seems to me that we forbid only things that Nochrim normally worship. If we do not know that they worship something, it is permitted. This is our custom; we never heard anyone protest.

Rambam (Hilchos Avodah Zarah 3:11): Similarly, one may not make forms of the sun, moon, stars and constellations - "Lo Sa'asun Iti", do not make forms of those who serve Me above. This is even on a tablet.

Rosh (3:5): R. Gamliel had forms of the moon on tablets and the wall for interrogating witnesses. We ask that "Lo Sa'asun Iti" forbids forms of the sun, moon, stars and constellations. We answer that he bought the forms from a Nochri. Shmuel told Rav Yehudah to get rid of a ring with such a form. This is because the form protruded. One may stamp with such a ring, but not wear it. If the form is recessed, one may wear it, but not stamp with it. We discuss a form of the sun, moon, stars, constellations, or a person, which are forbidden. One may not even keep them if a Nochri made them, due to suspicion. Why didn't the Gemara answer that R. Gamliel's forms did not protrude? R. Tam and the Riva say that regarding the sun, moon stars and constellations, protruding and recessed forms are the same, for they appear recessed to us in the sky.

Poskim

Shulchan Aruch (YD 141:4): Images of the sun, moon and stars are forbidden whether they are protruding or recessed.

Taz (13): The Gemara and Tur forbid also the constellations. Why does the Shulchan Aruch (Sa'if 6) permit animals? A kid, lamb, ox and lion are among the constellations! The Beis Yosef (Sof ha'Siman) challenged R. Elyakim, who forbids a lion. Also, fish is a constellation. Rav used to draw a fish (for his signature - Gitin 36b)! If it is Asur, even what does not protrude is Asur! Perhaps the constellations have special forms (but a Stam kid, lamb... is permitted), and only these one may not keep, but one may not make even a standard image of a constellation. This explains why we could not answer for R. Gamliel that his moon was not like a king (according to the Rema (Sa'if 3), who forbids a moon only if it is like a king). The Bach forbids making any image of the constellations. Even though even recessed images are forbidden, a flat picture is permitted, for it has no substance. Even so, it is improper to illustrate the constellations in Machzorim in Tefilas Geshem, for he intends for the form of the constellations.

Rema (3): Nowadays that Nochrim do not worship these things, one may benefit from such images, but one may not keep them. Some are stringent about everything taught, even nowadays that they do not worship them.

Beis Yosef (DH umi'Kol): Why does the Tur forbid even nowadays? Nowadays, the Notzri religion spread among all Nochrim we heard of, and they do not observe another idolatry. A sun, moon or Darkon should be permitted, for surely they do not worship them! R. Yerucham permits benefit from such images, but not keeping them. However, Tosfos (43b DH She'ani) connotes that there is no difference between the time of the Gemara and nowadays.

Shach (16): Even nowadays, even the first opinion forbids keeping them, due to suspicion.

Shach (17): I never heard of anyone who is stringent. Why should we forbid what no one worships? I see no source that Tosfos forbids. The Tur relied on what he wrote above, that even images on honorable Kelim are permitted if we know that they are not worshipped.