My understanding is flat earth was presented as sarcasm in the 1800's (?) to polk fun at people who weren't "enlightened."
As you wrote anyone who's been out to sea, stood on a seashore, or been on a mountian see the world is round.
Eratosthenes calculated the diameter of the earth back in ~276 BC.
Eratosthenes calculated the circumference of the Earth without leaving Egypt. He knew that at local noon on the summer solstice in Syene (modern Aswan, Egypt), the Sun was directly overhead. (Syene is at latitude 24°05′ North, near to the Tropic of Cancer, which was 23°42′ North in 100 BC) He knew this because the shadow of someone looking down a deep well at that time in Syene blocked the reflection of the Sun on the water. He measured the Sun's angle of elevation at noon on the same day in Alexandria. The method of measurement was to make a scale drawing of that right triangle with the vertical rod and its shadow as its legs and to measure the acute angle subtending to the shadow. This turned out to be about 7°, or 1/50th of the way around a circle. Taking the Earth as spherical, and knowing both the distance and direction of Syene, he concluded that the Earth's circumference was fifty times that distance.
His knowledge of the size of Egypt was founded on the work of many generations of surveying trips. Pharaonic bookkeepers gave a distance between Syene and Alexandria of 5,000 stadia (a figure that was checked yearly). Some[who?] say that the distance was corroborated by inquiring about the time that it took to travel from Syene to Alexandria by camel. Carl Sagan said that Eratosthenes paid a man to walk and measure the distance. Some claim Eratosthenes used the Olympic stade of 176.4 m, which would imply a circumference of 44,100 km, an error of 10%, but the 184.8 m Italian stade became (300 years later) the most commonly accepted value for the length of the stade, which implies a circumference of 46,100 km, an error of 15%. It was unlikely, even accounting for his extremely primitive measuring tools, that Eratosthenes could have calculated an accurate measurement for the circumference of the Earth. He made five important assumptions (none of which is perfectly accurate):
- That the distance between Alexandria and Syene was 5000 stadia,
- That Alexandria is due north of Syene
- That Syene lies on the Tropic of Cancer
- That the Earth is a perfect sphere.
- That light rays emanating from the Sun are parallel.
Eratosthenes later rounded the result to a final value of 700 stadia per degree, which implies a circumference of 252,000 stadia, likely for reasons of calculation simplicity as the larger number is evenly divisible by 60. In 2012, Anthony Abreu Mora repeated Eratosthenes's calculation with more accurate data; the result was 40,074 km, which is 66 km different (0.16%) from the currently accepted polar circumference of the Earth.
Seventeen hundred years after Eratosthenes's death, while Christopher Columbus studied what Eratosthenes had written about the size of the Earth, he chose to believe, based on a map by Toscanelli, that the Earth's circumference was one-third smaller. Had Columbus set sail knowing that Eratosthenes's larger circumference value was more accurate, he would have known that the place that he made landfall was not Asia, but rather the New World.
Tom, I have witnessed the earth's cuvature while on a Merchant Marine vessel headed for Germany. That was 1965. Even so, we have maps that are always four directions and we do not understand which way is up. Why don't the people at the bottom of the earth "fall off?" Why are people telling us which part of our galaxy something is in? Maybe we have a flat universe instead and the curvature of the earth as I witnessed was just caused by sheer weight.
As for the "big bang" I wasn't around so I do not know.
P.S. I hope you know I am kidding about a flat earth.
Have any sailors on this web site witnessed it?
A green flash, which occurs more commonly at sunset — but can also occur at sunrise — is a phenomenon in which part of the sun can be observed suddenly and briefly changing color. It usually lasts only a second or two — which is why it is referred a flash — as the sun changes from red or orange at sunset, for example.
The green flash is viewable because refraction bends the light of the sun. The atmosphere acts as a weak prism, which separates light into various colors. When the sun's disk is fully visible above the horizon, the different colors of light rays overlap to an extent where each individual color can't be seen by the naked eye.
More in the above link.
I no longer debate points of science with religionists. Off topic subjects are therefore, evolution, global warming and flat earth amongst many others. There is no point debating scientific facts with idiots.
Gentlemen, keep in mind here that theists have all the answers. I use that approach against them in comical ways. They always "know." They act surprised that I don't know and I tell them it is OK not to know. How do we know everything? An invisible man in the sky told you. How? It's as if your invisible man is imaginary.
I will not debate a scientific point with you. Neither one of us are scientists. Religious people make things up. They use their interpretation of their book to do so, but somewhere in that same book is a contradiction. This is because it is not just one book, but many. Changing times creates changing people so the interpretation of the holy books will change right along with that. The great problem is that none of it is done in a logical way. Believers frantically scramble to support and prove their religion, and all without proof.