On 1/25/2025 1:04 AM, Fred Cisin via cctalk wrote:
On Fri, 24 Jan 2025, Frank Leonhardt via cctalk wrote:
The theory that the earth is flat is clearly disproven. Aristotle
worked it it was basically spherical, yet crackpots believe it's flat
to this day - often because their scripture said otherwise.
A simple home experiment:
Find two points, such a hill/mountain-tops that are visible from each
other, but 10 or 20 miles, at least apart east/west..
Set up a vertical tube or slot.
When the sun is directly overhead, tell the other person, and see how
long it takes before the sun is directly overhead at the other location.
if you don't want to use cellphones, since that would not have been
available in the past, use smoke signals.
I found about a minute to go 15 or 20 miles.
15 or 20 miles in a minute is about 1000 miles an hour.
Since the sun's cycle is 24 hours, that would mean that it travels
24,000 miles in a day. And therefore, the circumference of the earth is
about 24,000 miles.
If you make up some jigs for measuring, and average the readings over a
few days, you can get a fairly accurate estimate of the circumference of
the earth. Divide by PI if you want the diameter.
With visual signaling, instead of cellphones, you might lose a little
accuracy, but it was well within the reach of technology for thousands
of years.
And, it would was close enough to make it obvious that if you want to
sail west from europe to the indies, you are going to run out of
supplies long before you get there! Unless you are dumb lucky, and
happen to bump into some land on the way.
Columbus had a bad idea that the earth was MUCH smaller, so he thought
that he could make it.
Or, he knew how big the earth was, but based on maps older than he was,
he knew there was another continent between Europe and Asia traveling
west and bilked the Spanish royalty into financing his boondoggle. :-)
He did not prove that the earth is round; that would have to wait for
Magellan.
That was never his intention.
And, except for "flat-earthers", educated people knew that the earth was
round, and even had a reasonable estimate of how large.
bill
