Hello all,

As many of you know, April 5, 2013 marks the 500th anniversary of the official Spanish discovery of Florida by Juan Ponce de Leon. I've been asked to present to a local historical society, and I want to bring out some of the astronomy related to this event, particularly the colonial Spanish practice of naming places after feast days in the Church's calendar. Ponce de Leon recorded that he named Florida not just for the lush vegetation he saw, but because it was on Palm Sunday, "la Pascua de Florida." 

Immediately you will be able to tell me the moon phase, which would be waxing gibbous, because the (simple formula) for determining this moveable feast is that Easter is always the Sunday following the first full moon that occurs after the vernal equinox.

What I need help with is confirmation that the April 5th date is from the Julian, not the Gregorian calendar. My calculations (and my handy software sky program!) show that there were full moons on March 20, 1503 and again on April 19, 1513. If it were March 20, then Easter would have occurred in March, not April. I seem to recall that Spring began closer to March 25th back then anyway, before the Gregorian calendar was put into place in 1582. If it's the April 19 full moon, that's obviously too late, unless the date that we celebrate the discovery has not been recalculated to the Gregorian date. In that case, I think there were 9 - 10 days difference between the two, which would put the full moon around the 10th of April, and then everything works out. I had become accustomed to working with dates that already had been reformulated (the famous, "George Washington wasn't born on Washington's birthday" example coming first to mind.) So my speculation is that the old Julian calendar date was kept because Ponce de Leon cited it in his journal entry.

If some knowledgeable colleague out in the Dome-L community would be kind enough to check my work I would be very happy as I don't want to go out there looking like a complete idiot (partial idiocy is always acceptable of course.) I already know that he wasn't really looking for the Fountain of Youth...

Thanks!

Jon U. Bell, Associate Professor of Astronomy
Hallstrom Planetarium Director
Indian River State College
3209 Virginia Avenue
Fort Pierce, FL 34981 USA
Telephone: (772) 462-7515


 

=========================================================
Important Subscriber Information:

The Museum-L FAQ file is located at http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed information about the listserv commands by sending a one line e-mail message to [log in to unmask] . The body of the message should read "help" (without the quotes).

If you decide to leave Museum-L, please send a one line e-mail message to [log in to unmask] . The body of the message should read "Signoff Museum-L" (without the quotes).