earth does not travel around the sun with a constant speed. His imprecision, according to Abraham ibn Ezra, was a function of the desire of the time to avoid the necessity of manipulating fractions.Rabbi J. David Bleich. Bircas Hachammah, Blessing of the Sun: Renewal of the Creation: a Halachic Analysis and Anthology. Brooklyn, N.Y.: Mesorah Publications ltd, 1981. . p. 50. Codification in Jewish law The Shulchan Aruch states that this blessing, generally said upon experiencing natural phenomena, should also be recited upon witnessing the chammah bi-tkufatah ( = sun at its turning point). This term, quoted from the above-mentioned Beraita, is explained by the Chofetz Chaim as referring to the point in time at which the Sun returns to the start of its cycle, similar to when it was created. As explained below, the blessing is recited on the morning after the Sun completes its cycle; ideally, it should be recited at sunrise, referred to in Jewish law as haneitz hachammah. It is preferred to recite the blessing with a multitude of people, in keeping with the principle of b'rov am hadrat melech. The Magen Avraham and the Levush insist that it be recited within the first three hours after sunrise. The Mishnah Brurah, however, states on behalf of numerous Achronim that it is permitted the blessing to be recited until halachic noon. According to most opinions, the blessing may only be recited if the Sun can be seen. However, if the Sun is completely blocked by clouds, there is a minority view that allows the blessing to be recited nevertheless, because essentially the blessing is on the concurrence of the Sun's physical position with the timing of the day. Overview According to the Babylonian Talmud, the Sun makes a 28-year cycle to return to the position that it was in when the Universe was first created at the time (Tuesday evening) it was created. According to Jewish tradition, the Sun was created on the fourth day (, yom revi'i) of the week of Creation. Because Jewish law considers the time unit of a day to span from evening to evening, the beginning of the halachic fourth day, so to speak, is on Tuesday evening at sundown. The 28-year cycle therefore begins and ends at the point in time when the Sun was created, this being sundown on Tuesday. The Sun only returns to this exact position at sundown