Many leftists mistakenly believe that the concept of a round Earth began with Galileo, and that the notion of a flat earth has been carried forward by backwards, conservative, religious people. In fact, educated people have known the earth is round since before the time of Christ.
When they troll about the firmament, it is a (they think) sly sideways slap at fundamental Christians.
In fact, educated people have known the earth is round since before the time of Christ.
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Since Old Kingdom Egypt, in fact.