A most simple deduction made around 200 bc by the Astronomer Eratosthenes. A Globular spheroid is our home ^^ Using the simple concept that shadows must be the same length on a flat surface, but different when on a curved surface, Eratosthenes was able to not only show that the earth was round, but to measure the actual size of it. Just remarkable that it was done in 200 bc, which is almost a thousand years before it was "officially" discovered.
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