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    Happy Birthday, John Harrison
    From: Frank Reed
    Date: 2020 Mar 24, 20:24 -0700

    John Harrison, the famous creator of the first successful marine time-keeper, later known as a chronometer, died on March 24, 1776. He was also born on March 24 back in 1693. So happy birthday to him! But it wasn't the same day of the year, of course, because two different calendars were in use during his lifetime. By the calendar of his later years, which is the calendar we still use today, Harrison was born on April 3, 1693, and my birthday wish is thus a bit early... What's the significance of that in terms of positional astronomy and celestial navigation? In other words, how could you, as a celestial navigator, prove that those two March 24th dates were not the same day in some absolute time sense? What does it mean to say that it's March 24?

    (I don't have any one specific answer in mind... just opening this up as food for thought)

    Frank Reed

       
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