On this day in 1723 – February 17th – German cartographer and astronomer Tobias Mayer was born.

Mayer's chart of the full moon was the standard for half a century, but he's best known for his lunar tables. The accuracy of the lunar positions (and the theory behind them) enhanced the lunar distance method for determining longitude at sea. It enabled navigators to find longitude accurately to half a degree.

Mona Evans
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