Was Columbus the first person to discover that the earth is round?

Answer 1

Eratosthenes of Cyrene first put the motion forward and even calculated the diameter, but Nicholas Copernicus and Galileo Galilei first put the idea into the public eye. Ferdinand Magellan was the first one to sail around the world.

Answer 2

Greek and Phoenician mariners and astronomers 2500 years ago knew that the Earth was spherical, because of the way ships disappeared by sinking below the horizon as they sailed from shore. We have no idea who was the first to realize it, but the Greek mathematician Eratosthenes used observations of the Sun's angle at noon to calculate the diameter of the Earth - a computation that ONLY would have made sense if he knew the Earth to be round.

Eratosthenes

Answer 3

The length of the shadow of a vertical stick stuck in the ground at midday in two places many miles apart. This told him that the verticals must be at an angle to each other, and scaling this angle up to 360 degrees gives the circumference of the earth by using the same scaling factor with the separation of the locations.

Answer 4

Every intelligent person since the ancient Greeks knew that the Earth was round, but nobody actually sailed all the way around until the expedition originally headed by Ferdinand Magellan.

Magellan himself was killed having crossed only about 2/3 of the Earth's circumference.

Answer 5

Early sailors and people living on the coast were probably the first to learn this. As a ship sails away from shore, the coastline sinks out of view, and only tall buildings or mountains remain visible. From the shore, the hull of the ship disappears while its masts are still visible, indicating that the ship is going DOWN - which only makes sense if the Earth is curved. That's why ships' lookouts are in the "crow's nest" at the top of the mast, or why lighthouses are made to be very tall.

Another persuasive piece of evidence is the appearance of the CURVED shadow of the Earth on the Moon during a lunar eclipse; we can plainly see that the Earth is round.

In 240 BC, the mathematician and astronomer Eratosthenes of Alexandria was able to calculate the size of the Earth by knowing that on a particular day, the Sun was directly overhead at noon at one city, and several degrees off the vertical at noon in another.

Answer 6

No, Galileo is credited with discovering the telescope. The discovery that the Earth was round was thousands of years earlier. He did agree with Copernicus that the earth revolved around the sun. Around 150 AD, Claudius Ptolemy, a Greek geographer, drew maps that showed the earth as curved.

Answer 7

To PROVE it? Juan Sebastián Elcano, who took over the command of the flotilla of three vessels (Concepción, Trinidad and Victoria) which had sailed from Spain under the command of Ferdinand Magellan. Magellan himself was killed in what are now the Philippine Islands, and only the vessel Victoria with Elcano in command returned to Spain three years later, having completed the first circumnavigation of the world.

However, observers since the ancient Greeks on had known that the world was a sphere, and even calculated its size within a few percent of the actual value. But there is a difference between KNOWING that something is true, and providing PROOF.

Answer 8

The "why" is easy : Because he could!
The "how" is interesting and shows a considerable acuity of mind.
Eratosthenes heard that in the ancient Egyptian city of Swenet (known in Greek as Syene, and in the modern day as Aswan) on midday on midsummer the Sun would shine down deep vertical wells and the reflection of the head of someone looking down the well would block the Sun's light. This meant that the Sun was directly overhead (zenith).
At that date in Alexandria where Eratosthenes worked and studied, the sun made an angle with the vertical of 1/50th of a full circle. He assumed (correctly) that the Sun was far enough away that the rays could be considered parallel. and so surmised that the distance from Alexandria to Syene (he was Greek) was 1/50th of the circumference of the Earth. The Egyptian surveyors of the preceding 2000 or so years had made fairly accurate measurements of the country and Eratosthenes used the figure of 5000 stadia for the distance between Alexandria in the north to Syene in the south to calculate the circumference of the Earth.
There is some debate as to the exact length of the stadion in his day but in all accounts it is between 145 and 180 meters. If it were 157.5 meters as several experts claim, his measurement is less than 1% off today's accepted value.

Answer 9

We do not know who was the FIRST to argue that the Earth is round, but 2400 years ago, the Greek and Phoenician astronomers and mathematicians already knew it. The Greek mathematician Eratosthenes calculated the diameter if the Earth quite accurately by observing that on the summer solstice, the Sun's light would shine straight down into a deep well, but on the same date in another city, the Sun's rays strike the Earth at an angle.

Answer 10

The earth actually isn't round, it is a slight oval shape, though it is easier to draw it a complete sphere on maps. I know that people used to think the earth was flat, and tried to find out where it ended, but I think they travelled round the world and ended up in the same place again, then came to the conclusion that the earth is round.