Who is this majority and how many of the ones that we usually Pasken from?
The Gemara in Pesachim is obviously cryptic, since anyone looking up in the sky will see the sun going down, not up. Perhaps the question was how to look at it: is the sun going away from us — above, beyond our reach — or is it merely going down, as the physical fact is.
Chazal did not know everything. Some Tanoim were able to derive scientific facts from Pesukim, as was the case with Reb Yehoshua ben Chananya and the Greek philosopher, and the sending of broken musical instruments to Egypt, and the consulting a doctor or sitting out on a farm for a year. However, all over Shas you can find Braysos about scientific facts. You’ll notice that the only science accepted by Chazal are Mesoras and Braysos. Rav Popa is often Medayek science from Mishnos. Chazal make it clear when their information is from the outside. Bottom line is, we accept their words unquestingly just like they accepted the words of the Tanaaim unquestingly.