Who discovered that the world is round and when was the discovery made?

Answer 1

Columbus discoved the earth is round in 1492 b/c people made fun of Chistopher Columbus for trying to go the long way b/c they thought you would fall off the edge of the earth.

Answer 2

Nobody is sure who first deduced that the world is round. It is most likely that it was done by observing the Earth's shadow on the Moon during a lunar eclipse. Aristotle (384-322 BC) said that it was common knowledge, at least among the learned, so it's been known for at least 2,500 years.
We do know that Eratosthenes of Cyrene was the first to accurately estimate the Earth's diameter, around 220 BC. How he did it is detailed at Astronomy Online.

What he did was use the information that, at noon on the Summer Solstice, the sun shone to the bottom of a well in Syene (now called Aswan), Egypt. This meant that the sun was making a 90° angle to the ground on that day, in Syene.

Eratosthenes then measured the angle of sunlight to the ground in Alexandria, Egypt, at noon on the same day. He used that angle to calculate what fraction of the Earth's circumference (which is 360°) was between Alexandria and Syene. Since he knew the distance to Syene, and that it was exactly south of Alexandria, he was able to calculate the Earth's circumference.

Actually, he didn't have the distance quite right--and Syene isn't exactly south of Alexandria, either.
This was the first reasonable accurate measurement of the Earth's circumference, and it came to about 40,000 km (25,000 miles). We now know that this is an overestimate, but not by too much.

Answer 3

Belief in a flat Earth is found in mankind's oldest writings. In early Mesopotamian thought, the world was portrayed as a flat disk floating in the ocean, and this forms the premise for early Greek maps like those of Anaximander and Hecataeus.

By classical times an alternative idea, that Earth was spherical, had appeared. This was espoused by Pythagoras apparently on aesthetic grounds, as he also held all other celestial bodies to be spherical. Aristotle provided observational evidence for the spherical Earth, in that travelers going south see southern constellations rise higher above the horizon. This is only possible if their horizon is at an angle to northerners' horizon. Thus Earth's surface cannot be flat. Also, the border of the shadow of Earth on the Moon during the partial phase of a lunar eclipse is always circular, no matter how high the Moon is over the horizon. Only a sphere casts a circular shadow in every direction, whereas a circular disk casts an elliptical shadow in most directions.

The Earth's circumference was measured around 240 BC by Eratosthenes. Eratosthenes knew that in Syene (now Aswan), in Egypt, the Sun was directly overhead at the summer solstice, while he estimated that a shadow cast by the Sun at Alexandria was 1/50th of a circle. He estimated the distance from Syene to Alexandria as 5,000 stades, and estimated the Earth's circumference was 250,000 stades and a degree was 700 stades (implying a circumference of 252,000 stades). Eratosthenes used rough estimates and round numbers, but depending on the length of the stadion, his result is within a margin of between 2% and 20% of the actual circumference, 40,008 kilometres. Note that Eratosthenes could only measure the circumference of the Earth by assuming that the distance to the Sun is so great that the rays of sunlight are essentially parallel. A similar measurement, reported in a Chinese mathematical treatise the Zhoubi suanjing (1st c. BC), was used to measure the distance to the Sun by assuming that the Earth was flat.

Answer 4

I don't want to repeat the previous (correct!) answers
about Eratosthenes. But Remember : Eratoshenes
was the first who did the calculations about the size of
Earth! He knew by his teachers that Earth is a sphere.
Aristarhos of Samos was the first who wrote it in one of his
books (And that counts!!!)

I have a good comment about how long a "stadion" was
(Stadia is plural in Greek --> One: stadion --> many: stadia)

One stadion was the minimum race in ancient Olympics.
Different cities different stadia.
One stadion was 200 steps for an average man.

In Olympia the stadium was 162,2m = 0,1008 miles
This gives a perimeter of 25,202 miles

This is less than 1% overestimate.

Answer 5

Christopher Columbus

Answer 6

Man has believed the Earth to be round since pre-history.

Eratosthenes, (276 BC-194 BC) Librarian of Alexandria wrote a treatise "On the Measurement of the Earth" in which he gave a figure for the Earth's circumference of 250,000 stadia. Depending on how long a stadia actually was this is the equivalent of about 23,000 miles, close to the true figure of 24,900 miles.

Answer 7

This was known to Aristotle (4th century BC), due to the shape of the Earth's shadow on the face of the Moon during a lunar eclipse. It was widely known in antiquity and the middle ages, and Aristotle may not have been the first, but is the first who wrote about it, as far as we know.

Answer 8

Christopher Columbus - Famous Explorer

Answer 9

Hi. When a ship sails away, the hull goes over the horizon before the mast. This was observed thousands of years ago, and folks reasoned that the earth was as least curved.

Answer 10

Nicolas Coprernicus said it was flat a long time before gallilio around 1400ad. gallilio was tortured by the pope for saying it and then was forced to changed his mind after the punishment.