Magellan's circumnavigation of globe Aug 10, 1519-22

  Sun at 28 degrees 2 ‘ Libra at 0 hrs GMT Oct 12, 1492, Julian calendar--shown.

   We need ~5 a.m. San Salvador Is. time (which at 74.5 W. longitude is close to longitude of Soledad, Colombia), hence the Sun’s position requires ~9 more hours, or Sun near 28 degrees 24’ Libra to be predawn at San Salvador Island in 1492, on Julian calendar.  

  Our present calendar (due to equinoctal progression rate of 1 degree every 72 years) shows that Sun reaches 28 degrees 24’ Libra this year at 10 p.m. 21 October for the time meridian of San Salvador Island.

-r.

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Magellan's circumnavigation of globe Aug 10, 1519-22:

  Like Columbus before him, Magellan's primary objective was to open up a western trade route for Spain to Asia, since Spanish ships were barred by treaty with Portugal from using the route around Africa. Columbus' discovery of a new continent presented Magellan with the additional challenge of finding a passage through the new world to the Southeast Asian kingdoms, then referred to as the Spice Islands.

  After crossing the Atlantic Ocean and coming to the coast of modern-day Brazil, Magellan and his squadron of five ships turned south. Surviving a mutiny and the wreck of one ship, Magellan sailed the length of South America until finding a deep-water strait near the tip of the continent – the strait that now bears his name.

  He lost another ship, which defected and returned to Spain, but passed through the 373-mile-long strait to become the first European to enter the Pacific Ocean from the east.  Magellan himself christened it the Pacific Ocean ("Mar Pacifico") because of its relative placidness compared to the stormy Atlantic.  https://www.wired.com/2010/08/0810magellan-sets-sail/