User talk:68.57.98.85

Lighthouse question
The answer is actually very complex, as it needs to consider height of the light, height of the observer, power of the light and weather. Search on lighthouse height visibility for articles. For the power variable, consider that one can see a lit light bulb from farther away than a lit match. Math problems that address height and Earth's curvature ignore this by assuming the light is adequately powerful to be seen at great distances. David notMD (talk) 11:05, 16 May 2018 (UTC)