how did ancient people know that the earth is sphere in shape?

Answer 1

Many many ancient civilizations thought the Earth was round. For example, the Inuits, who were isolated from other tribes knew the Earth was round by simply looking at how the stars rose and set. The notion of the Earth being flat was brought around by the medieval time period, were all past knowledge of the Greeks, Romans, and Egyptians was lost. We think that we are so modern, but in fact by the turn of the century we were just catching up with some of the ancient world's greatest minds. For example Heron of Alexandria was creating clocks, automated plays, and a steam machine. Perhaps we want to show haw much we have improved by downscaling our forebears' achievements.

Answer 2

Eratosthenes (Greek Ἐρατοσθένης) (276 BC - 194 BC) was the first person to calculate the diameter of the earth with any accuracy. We have to assume that other people might have realized that the earth was a sphere by simply analogy to the shape of the moon and the sun both round like spheres.

Eratosthenes was Greek born but lived and died in Alexandria, Egypt.

Of course earlier and even later dates there were plenty of people who thought the earth was flat. Even the New Testament refers to the earth as being flat with the story about the devil lifting Jesus to a high mountain so he could see ALL of the kingdoms of the earth. (A clear proof that the Bible was written by man and not some omniscient God.) Clearly the writers thought the world was flat.

Answer 3

Long long ago, peopel though that our earth is flat and there is an end for our earth.But that is completely wrong.our are not a exactly sphere.There was one day a person noticed that there was a boat look like coming out gradually from the water of sea. After that there was someone predict that our earth is a shpere, but there were still many people not belive that.Lastly, sceince proved that our earth is a sphere.

Answer 4

Actually, Eratosthenes was Greek, not Egyptian, but yes the theory is basically the same. The following is copied from the Wikipedia article:

Eratosthenes knew that on the summer solstice at local noon in the town of Syene on the Tropic of Cancer, the sun would appear at the zenith, directly overhead. He also knew, from measurement, that in his hometown of Alexandria, the angle of elevation of the Sun would be 7.2° south of the zenith at the same time. Assuming that Alexandria was due north of Syene he concluded that the distance from Alexandria to Syene must be 7.2/360 of the total circumference of the Earth. The distance between the cities was known from caravan travellings to be about 5000 stadia: approximately 800 km. He established a final value of 700 stadia per degree, which implies a circumference of 252,000 stadia. The exact size of the stadion he used is no longer known (the common Attic stadion was about 185 m), but it is generally believed that the circumference calculated by Eratosthenes corresponds to 39,690 km.

Answer 5

they had two logical reason for that:
1.they had determined that the earth has a curved shadow on the moon, so earth sould be spheriacal.
2.they had discovered that when they traveled to the south, the saw the Northen Star downer in sky, thereby they determind the earth is sphere in shape.

Answer 6

Because some of those people of that day were smarter than some people who live today:

"The earth is flat. Whoever claims it is round is an atheist deserving of punishment."

Yousef M. Ibrahim, "Muslim Edicts take on New Force",
The New York Times, February 12, 1995, p. A-14.


1995 AD not BC

LOL

Answer 7

An egyptian named Erotosthenes noticed that on June 21 that a stick casted no shadow at noon in Alexandria and 800 miles south a significant shadow was casted at 7º.

So using trigonometry, he was able to deduce that the the world was round and about 25,000 miles in circumference.

Answer 8

1) Watching ships "sink" at the horizon.

2) Seeing a curved Earth shadow on the Moon during a Lunar Eclipse.

Answer 9

In addition to what kreevich said, Aristotle noticed that stars crossing the meridian did so at different elevations in different latitudes. (The meridian is the great circle arc that passes from due north on the horizon, through the celestial pole, through the zenith, to due south on the horizon.) If the latitude difference is large enough, constellations can be seen in one place that are invisible from the other.

Answer 10

The ancient Greeks found out because the Sun didn't cast the same length of shadow everywhere at noon.