Who can tell me the simplest proof, easily verifiable by anyone, that the Earth is round (spherical)?

Question

I’m still (after 5 days) not satisfied with obtained answers. It is too complicated or not easily verifiable by anyone. Please try with other solutions.

Answer 1

Satellite Pics.
☆

Answer 2

Here you go dude:
Ouros


Cecil replies:

I know you mean this question to seem delightfully impertinent, Allan, but you're about 30 years too late. There are, after all, innumerable photographs of the earth taken from space which reveal it to be spherical. Assuming you are not about to join the Flat Earth Society in proclaiming these a fake, I gather your complaint is that looking at a photo doesn't qualify as "personal experience." Big deal. I've never personally experienced Disney World, either. Most of what we know about anything depends on taking somebody else's word for it.

That said, there are a few home-demonstration-type indications--not proofs--that the earth is a ball. We'll start with ones you've already thought of:

(1) Departing boats gradually sink below the horizon, as do buildings on the shore from the viewpoint of the sailors. Admittedly this only proves the earth is round right where you are--the frisbee hypothesis.

(2) "The sphericity of the earth is proved by the evidence of ... lunar eclipses," Aristotle says. "For whereas in the monthly phases of the moon the segments are of all sorts--straight, gibbous [convex], crescent--in eclipses the dividing line is always rounded. Consequently, if the eclipse is due to the interposition of the earth, the rounded line results from its spherical shape" Of course a frisbee, properly angled, would make a round shadow too. But if the frisbee rotated while the eclipse was in progress, the curvature of its shadow would change. The earth's does not.

(3) The constellations shift relative to the horizon as you move north and south around the globe, something that could only happen if you were standing on a sphere. (You may have to draw a few diagrams to convince yourself of this.) Given sufficient world travel combined with careful observation on your part, the frisbee hypothesis becomes well-nigh insupportable. I suppose this doesn't qualify as a home experiment, but I never said science would be easy.

--CECIL ADAMS

Answer 3

The time zones. The sunrise and sunset times differ by about 4 seconds for each mile east or west in our temperate latitudes. You would think that people in the Middle Ages when they invented clocks small enough to carry on trips would have begun to suspect that something wasn't quite right when they didn't sync with local time.

Everyone still forgets the small towns everywhere, which typically never have their own sunrise/sunset times as if they aren't important enough. So a C/W song goes: "Some people say the world's not round and drops off sharp at the edge of town. They say the world is really flat because when people leave town they never come back."

Answer 4

Well, the question has been around for years, no pun intended. Proof lies in mathmatics and science etc. The easiest way I know is to look at the horizon from a high point above an ocean and see how it bends away. Also look at the picutres, live television etc from the space station. Look at the Moon and how it rotates. But I really have no concrete proof, even with all the science etc. we have today, some stubborn people insist the world is indeed flat.

Answer 5

Lots of good answers to this one. For example, take a trip of a thousand miles or more east or west and see what happens to the time of sunrise or sunset if you don't reset your watch to the new time zone. But I particularly wanted to comment on the measurement of the earth's size by the ancient Greeks. It happened, but not quite as one responder said. Eratosthenes, curator of the great library at Alexandria in the third century BC, was traveling in the south of Egypt at Syene [now Aswan], and noticed at midday at the solstice that the sun shone directly down a well, illuminating the bottom. He knew that this didn't happen at home, and figured out why. He measured the distance returning home, measured the angle of the sun there, and got a pretty good answer. (We don't know exactly how good because the size of the distance unit that he used has been lost.)

Answer 6

Probably the oldest test is the easiest, it was done long time ago by Greeks, use two poles of the same height, place then perpendicular to the surface of hearth, on the same meridian (that is one true north from the other) at a mile distance or two kilometers, and at noon (that is when the sun crosses the meridian, measure the shadow of both poles, you can use a bullet to coordinate the measure time, then doing some simple math you can find earth diameter.

Answer 7

Take a look at the shadow on the moon during a partial lunar eclipse. The curve on the shadow is a dead give-away. Indeed, that how the ancients were convinced about the spherical nature of the earth.

Answer 8

Climb a hill.

The horizon recedes.

It would not if the world were flat.

Its why sailors climb to the crows nest.

Proving the curve is a circle (more or less) is a lot harder.

Using shadows at noon at different locations does indeed allow an estimate of the radius though, assuming roundness.

Answer 9

Go to the ocean and watch a tall ship leave for sea. It will get lower and lower in the water until only the top is visible

Answer 10

Actually, it isn't. It bulges slightly at the equator and is slightly squished at the poles. But to tell that it isn't flat? Columbus didn't fall off the edge of the world when he "discovered" America.