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10/13/2015 – Ephemeris – Columbus was wrong!
Ephemeris for Tuesday, October 13th. The Sun will rise at 7:55. It’ll be up for 11 hours and 6 minutes, setting at 7:02. The Moon, 1 day past new, will set at 7:35 this evening.
Yesterday I recounted that Christopher Columbus was able to extort supplies from the native Jamaicans by using an eclipse table to predict a lunar eclipse. But let’s face it Columbus was lost. He wasn’t in India as he thought. He based his voyage on the erroneous belief that the Earth was less than 19,000 miles in circumference, when it’s actually 25,000 miles, which was the prevailing view of the day. That the Earth was round was known from the 3rd century BC, and measured quite accurately by Eratosthenes. Of course with the varieties of distance units of the day it was no wonder an error of that magnitude could be made. Of course did anyone think to remeasure the circumference of the Earth? Apparently not. Nowadays no scientist thinks of taking only one measurement. Columbus was lucky a continent was here, or no one would have heard from him again.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
A map of the western ocean (Atlantic Ocean) by Paolo dal Pozzo Toscanelli about 1474 which may have influenced Columbus. North America is superimposed at the proper longitudes. Credit: A literary and historical atlas of America, by Bartholomew, J. G. via Wikipedia. Click to enlarge.
Note that Cathay is China and Cippangu represents Japan. It was thought back then that the Eurasian continent spanned 180 degrees of longitude at the latitude of Spain, rather than 130 degrees it actually does Japan was thought to be bigger and farther off the Chinese coast. The phantom island of Antillia seems to date back to stories from Spain of the 8th century.
Ephemeris for the real Columbus Day for once, Monday, October 12th. The Sun will rise at 7:54. It’ll be up for 11 hours and 9 minutes, setting at 7:03. The Moon is new today, and won’t be visible.
On Columbus’ 4th voyage to the Caribbean he was stranded on Jamaica. For a while the natives of the island fed Columbus and his men. However due to the thievery of some of his crew, these people no longer trusted Columbus any refused them any more supplies. Columbus consulted a table of eclipses and found that a lunar eclipse was to occur on February 29th that year (1504), and that at his location the moon would rise in eclipse. He went to the leader of the people and said that they had displeased their god by refusing his crew food, and that the god would turn the Moon red in anger. It worked. As Arthur C. Clarke once wrote: “Any sufficiently advanced technology is indistinguishable from magic.”
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The moon rising from Jamaica February 29, 1504 as shown by Stellarium with some additional shadow darkening by myself.
Tomorrow I’ll look at what Columbus got wrong… Beside being lost.
I note for the record that Stellarium calendar dating includes what I call the Gregorian discontinuity. It drops the 10 days between October 4, 1582 and October 15th, which was the adjustment the Gregorian calendar makes to move ahead the actual vernal equinox from March 11 to the 21st. Christian churches always use the tabular value of March 21 as the vernal equinox for the calculation of the date of Easter. The old Julian calendar let that slip back about 3/4 of a day every century.
10/13/2014 – Ephemeris – Columbus uses knowledge of eclipses to get supplies from the natives
Ephemeris for Columbus Day, Monday, October 13th. The sun will rise at 7:55. It’ll be up for 11 hours and 6 minutes, setting at 7:01. The moon, 2 days before last quarter, will rise at 11:04 this evening.
On Columbus’ 4th voyage to the Caribbean he was stranded on Jamaica. For a while the natives of the island fed Columbus and his men. However due to the thievery of some of his crew, these people no longer trusted Columbus any refused them any more supplies. Columbus consulted a table of eclipses and found that a lunar eclipse was to occur on February 29th that year (1504), and that at his location the moon would rise in eclipse. He went to the leader of the people and said that they had displeased their god by refusing his crew food, and that the god would turn the Moon red in anger. The native peoples saw the red moon rising and promptly gave Columbus the supplies he wanted.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Christopher Columbus showing the lunar eclipse. From Camille Flammarion – Astronomie Populaire 1879, p231.
For more information in the Internet – search for Columbus lunar eclipse
10/14/2013 – Ephemeris – Columbus greatest and luckiest mistake
Ephemeris for Columbus Day, Monday, October 14th. The sun will rise at 7:56. It’ll be up for 11 hours and 2 minutes, setting at 6:59. The moon, 3 days past first quarter, will set at 4:12 tomorrow morning.
Today we celebrate Christopher Columbus’ big mistake. Mistake? Yes, mistake. Back in 1492 anyone with any education at all knew the earth was round. It was known since the Greek mathematician and geographer Eratosthenes calculated the circumference in the 3rd century BC. Columbus error was in misjudging its size. Columbus though the earth was only 18 thousand miles in circumference, which would put the east coast of Asia 3,000 miles west of the Spanish coast. Most academics held the circumference was nearer 25,000 miles, the correct value, putting Asia some 10,000 miles out. Columbus was very lucky that there was a continent in between. The native peoples, however, were not so lucky.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Bob Moler's Ephemeris Blog 