Aristarchus went a step further and computed the distance from earth, together with its size, obtaining a value of 20 earth radius for the distance (the real value is 60. The earth radius was known since Eratosthenes) His values, then, are computed as: A similar procedure was later used by Hipparchus, who estimated the mean distance to the moon as 67 earth radii, and Ptolemy, who took 59 earth radii for this value.
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| - Aristarchus went a step further and computed the distance from earth, together with its size, obtaining a value of 20 earth radius for the distance (the real value is 60. The earth radius was known since Eratosthenes) His values, then, are computed as: A similar procedure was later used by Hipparchus, who estimated the mean distance to the moon as 67 earth radii, and Ptolemy, who took 59 earth radii for this value.
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| - Aristarchus went a step further and computed the distance from earth, together with its size, obtaining a value of 20 earth radius for the distance (the real value is 60. The earth radius was known since Eratosthenes) His values, then, are computed as: The error in this calculation comes primarily from the poor values for x and . The poor value for is especially surprising, since Archimedes writes that Aristarchus was the first to determine that the Sun and Moon had an apparent diameter of half a degree. This would give a value of , and a corresponding distance to the moon of 80 earth radii, a much better estimate. A similar procedure was later used by Hipparchus, who estimated the mean distance to the moon as 67 earth radii, and Ptolemy, who took 59 earth radii for this value.
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