This is what JW.org says :
"The earth is suspended in empty space. (Job 26:7) Many ancient peoples believed that the world was a flat disk supported by a giant or an animal, such as a buffalo or a turtle."
http://www.jw.org/en/bible-teachings/questions/science-and-the-bible/
I think JW.org is missing something. I don't think that Jews believed that the earth was an sphere suspended in empty space.