According to the sages, the earth is flat and is covered by the heavenly firmaments, as a thick dome covers a platter. The progress of the sun: The sun crosses the thickness of the firmament in the east and from below it shines upon the earth. Throughout the day it moves westward and at the end of the day crosses the thickness of the firmament [in the west]. It exits the top of the firmament and crosses above the top [the nighttime hours] until it reaches the eastern side and again crosses under the firmament to begin the path anew. Therefore the sages divided the day into three parts. The first part starts from the sun entering the thickness of the firmament until it exits, the time from dawn until sunrise. The second part is when the sun shines upon the earth, from sunrise until sunset. The third part is from the sun’s entering the thickness of the firmament in the west until it exits the thickness above the firmament, from sunset until the stars come out.
One of the scholars, R’ Yochanan, measured the three parts of the day and estimated their lengths. From dawn until sunrise is one and a half hours, from sunrise until sunset is nine hours, and from sunset until the stars come out is an hour and a half. The scholars asked from whence he derived that the length of time between dawn and sunrise is an hour and a half. Answer: From the verses about Lot’s fleeing Sodom; he left at dawn and arrived in Zoar at sunrise, for it is written ” When the morning dawned, the angels urged Lot to hurry… The sun had risen upon the earth when Lot entered Zoar” (Genesis 19:15-23). One of the sages, Rabbi Chaninah, said that he knows these places and the distance between them is an hour and a half walk. This means that the time from dawn to sunrise is an hour and a half.
One of the scholars, Rava, estimated the length of the firmament and their thickness. In his opinion the circumference of the heavenly firmaments from the eastern to the western edges is 24,000 kilometers and the thickness of the firmament is 4000 kilometers. He drew this information from two sources. The information on the diameter of the firmament he received from his teacher, and the information about the thickness of the firmament from his own deductions. This is how he arrived at his deduction: since the sun, from sunup to sundown, travels the circumference of the firmaments in nine hours, and since dawn (when the sun first enters the thickness of the firmament) to sunrise (when the sun exits the firmament on the Earth side) is an hour and a half, the relationship between the thickness of the firmament and the circumference is 1:6. Therefore, since the circumference of the firmament is 24,000 kilometers, divided by six, the thickness is 4000 kilometers.
The scholars ask: one of the early sages, Rabbi Judah, said that the relationship between the thickness of the firmament and the circumference of the firmament is 1:10 and not 1:6 as the opinion of the scholars above. That early sage also determined that the time it takes for the sun to cross the thickness of the firmament, from dawn to sunrise, is only an hour and twelve minutes and not the hour and a half claimed by the scholars above.
Answer: The words of the early sage Rabbi Judah contradict the words of the scholars, and therefore their words are rejected. The scholars went on to ask: The sage R’ Chanina, who knew the area between Sodom and Zoar, determined that the distance between them is a walk of an hour and a half, but the early sage Rabbi Judah determined that it took Lot only an hour and twelve minutes to cover the distance between Sodom and Zoar. Answer: Lot fled Sodom and hurried on, as the Scriptures testify: “urged Lot to hurry”.
The scholars about the opinion which states the length of the earth is 24,000 kilometers. The early sages had ruled that the length of Egypt was 1600 kilometers, that of Kush 9600 kilometers, and that of the entire earth 5,760,000 kilometers. Answer: The scholar Rava’s words are rejected in favor of those of the early sages.
The scholars continued to ask about the opinion which states the length of the earth is 24,000 kilometers. The early sages ruled that the entire settled area is under a single star, and the proof is that a man can look at one star, walk east and still be under that star, walk in any direction and still be under that star. Therefore the entire settled area is under a single star. Even if we suppose that the continents, without the seas, is at least 4000 kilometers and under a single star — there are more than six stars in the firmaments, so the length of the earth is much greater than 24,000 kilometers. Answer: The words of the scholar Rava are rejected in favor of those by the early sages. The scholars went on to ask about the opinion which states the length of the earth is 24,000 kilometers. The early sages determined that the sun is directly over any specific piece of dry land on which people reside for one hour of the twelve hours it lights the earth. Proof of this is that the sun is over a person’s head at high noon only, for only one hour. The scholars then argued that aside from the settled areas there are oceans and deserts 11 times the length of the settled areas, and this certainly adds up to more than 24,000 kilometers. Answer: The words of the scholar Rava are rejected in favor of the words of the early sages. The scholars continued to ask about the opinion that the length of the firmament is 4000 kilometers. One of the early sages, Rabbi Yochanan the son of Zakkai, said that the thickness of the firmament is 7,300,000 kilometers: “It would take 500 years to cross the thickness of the firmament.” Answer: The words of the scholar Rava are rejected in favor of the words of the early sage Rabbi Yochanan the son of Zakkai.
(Babylonian Talmud, Tractate Pesachim 93b-94b)