A follow-up question might be whether the Earth could be flat and round, like a pancake. This would cause the shadow on the moon to be round, but the shape of the Earth to be flat. If the Earth were flat but rotating, its shape would be different for eclipses at different times of the day or night. Sometimes it would appear only as a line. The rest of the time it would appear like an oval or circle as it’s spinning. However, we know that the shadow the Earth casts on the moon during an eclipse has always been circular, regardless of time of day. This supports the idea that the Earth is a sphere.
