translation - What is the firmament?

In Genesis 1:6-8 the firmament and its creation are mentioned for the first time:

And God said: 'Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.' And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament; and it was so.

According to Wikipedia:

Like most ancient peoples, the Hebrews believed the sky was a solid dome with the Sun, Moon and stars embedded in it.

And the Jewish Encyclopedia says that:

The Hebrews regarded the earth as a plain or a hill figured like a hemisphere, swimming on water. Over this is arched the solid vault of heaven. To this vault are fastened the lights, the stars.

Now, when you make a google images search for the firmament, you'll get images depicting this idea like this one:

What surprised me the most is that, according to this site:

the Sages' view that the sun passes behind the sky at night - with the sky being believed to be a solid dome. It emerged that ALL of the Rishonim without exception, as well as many Acharonim, agreed that Chazal held this view.

Today, we all know this is not true. Does the Torah actually have such a distorted view of Earth and the Universe? Or is it a matter of interpretation? If we know the Chazal had it wrong, how can we trust their other interpretations? What is the current view on the firmament in orthodox Judaism?

Answer

The notion of a semi-spherical shell around the world, that the sun travels under during the day, and then back around and over at night is not necessarily the early Israelite understanding of cosmology. Most of the evidence for it is from an era when he Babylonians and Persians had much much more accurate observations than the Greeks, and it is the Babylonian cosmology. Tannaim (eg R' Eliezer on Bava Basra 25a) and the earlier Babylonian amoraim mapped the Torah to it, much the way rabbis today talk about Relativity and QM in the Torah. Given that it was the dominant science in their mileau, this was actually the rational choice. There is no indication that this was also "Ancient Hebrew" belief on the subject.

Meanwhile, in Israel, the later tannaim and amoraim switched over to the Ptolemaic system as Ptolemy's work took over the scientific consensus in their region. (See Pesachim 94b) And the debate shifts -- it is taken for granted that the raqia is a spherical shell around the earth, and the question they debate is whether the stars are affixed in the raqia, or move around on their own in front of it.

As opposed to all rishonim agreeing that all of chazal held the same view, it is uniquely the position of Rabbeinu Tam who says Rabbi Yehudah didn't actually switch views to the Ptolmeic system. The talmud in Pesachim says that he found the sages of Athen's words "appear to be more correct than ours", the sages' of Israel's. The idiom would usually mean that they are indeed more correct, as can be seen. Rabbeinu Tam (as relayed by the Shitah Mequbetzes on Kesuvos 13b) interprets the line as saying they appear more correct, but in reality the Greek astronomy is mistaken.

In contrast, the more straightforward read is that of R' Hai Gaon, R Sherira Gaon, the Rambam, the Tosafos Rid, the Rosh, the Ritva, the Smag....

In my opinion, it is more important to note the meta-issue... The general tendency is not an assertion that the Torah is a source of scientific theory. Chazal simply understood the verses as per then-contemporary science. And it is recorded in the gemara (except according to Rabbeinu Tam) that they changed their opinion when a new theory came along. Just as we today would with our contemporary science.

None of which means our sages thought the raqia was a shell because the Torah said so. Rather, that the Torah looked to them like it was talking about a shell they took for granted existed -- because their local scientists did. In the same way, it is likely 2,000 years from now, Jews are going to find our explaining Genesis using General Relativity quite antiquated and misguided. Still, it may be appropriate for us to do so, because it is our best understanding of the world and thus the verses.