Can you please cite proofs that the Earth is a sphere?

Answer 1

No. Because it isn't a sphere. It's an oblate spheroid.

Answer 2

The usual proofs are:
When things move beyond the horizon, the bottom part disappears first.
When you climb up, you can see further (the horizon is further).
At Lunar eclipses, Earth's shadow is always circular (once or twice could be the result of coincidence -- but every single time, whatever the angle?)
Earth has been orbited.
If you set out in one direction and travel long enough, you are back where you started from (still facing the same direction).

It is a rotating sphere: the Coriolis effect (an "inertial" force) is noticed in the movement of wind and weather patterns (and even in movement of rivers). It can be measured.
Foucault's pendulum.

HOWEVER,
it is possible to construct a mathematical model, where the Earth's surface marks the outside of the univers and everything else (including the Sun, galaxies...) is towards the centre. On this "concave Earth" we would be facing inwards towards the centre. If you see the whole thing as a finite 3-D space with a grid (x,y,z) centred on the centre, then distance is calculated using the inverse of the grid reference.
For example, the distance from the point (1,0,0) to the point (0.5, 0, 0) is 2. The closer you are to the centre, the longer you have to travel to move one unit.

Mathematically, everything that we can explain with our present system (Earth is a sphere in an infinite univers) can be explained with this other system.

"Supposedly no experiment can distinguish between the two cosmologies. Martin Gardner notes that 'most mathematicians believe that an inside-out universe, with properly adjusted physical laws, is empirically irrefutable'."

(Martin Gardner is a mathematics writer who wrote in Scientific American.)

The only reason we prefer a spherical (convex) Earth to the concave one is simply because the maths are far easier (and more believable). The idea of chosing the simpler of two systems when they appear to be equally useful, is called Occam's Razor: "All things being equal, the simplest solution tends to be the best one."

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The concave Earth is NOT the Hollow Earth concept whereby there is a hole at the pole allowing one to move from the outer earth to the inner earth. The Hollow Earth fails to explain many things, including how we can still reach the pole and be held by gravity at that spot.

Answer 3

The Earth has a Spherical shape. However the curvature of the earth is not Uniform.It varies and if you take away the ice at the poles and smooth all the mountains flat and all the sea were at the same level You would have a perfect "Sphere" where the surface gravity time of the earth would be the same no matter where you are located.You can say that the earth is a Spheroid but an aproximated one. The proof that the Earth is Spherical was first Given by astronaut Armstrong when he saw the earth from outer space he took a picture of the Earth. The Photogragh is positive visual proof that the earth has indeed a Spherical shape .It was not a flat disk as was believed in old days.
In the same way if we took a picture of the Universe from outside the universe it would also be spherical but more likely a flatened out sphere . Today scientists believe that our Universe is Flat. Imagine that.

Answer 4

Well, the earth is not a perfect sphere to be sure, but there are four important pieces of evidence. First comes from the use of telescopes. If one uses a telescope to watch ships, especially tall ships, sail away from land, what one sees is the hull of the ship disappearing over the horizon *followed* by the masts or smoke stacks or conning tower. This only make sense if the earth is curved like a sphere.

Second, ships that sail away do in fact go around the globe; something that would be hard to do if the earth weren't spherical.

Third, since most of the earth is either molten or lava-like gravitation, which act radially, pulls the earth into a spherical shape.

Finally, the shadow of the earth cast on the moon during a lunar eclipse is curved; and effect that would be hard to produce if the earth weren't spherical in shape.

HTH

Charles

Answer 5

You can tell Earth is a sphere from watching a lunar eclipse. During the eclipse the Moon crosses the Earth's shadow. This shadow is round, so it blocks the light from the Moon.

Another way you can tell Earth is a sphere is from watching ships as they go beyond the horizon. The ships appear to disappear below the horizon. They are actually following the curve of the Earth.

Answer 6

People have taken photographs of the Earth from space from many angles and it has always looked round.

Satellites can assume regular circular orbits around the Earth, whether polar spy satellites or geosynchronous communications satellites.

You can't see Topeka from anywhere except Topeka.

The Earth's shadow during a Lunar eclipse is always round, no matter what time of night it occurs.

Despite what the flat map says, the "circular" route is always shorter.

The Sun shines all day at the North pole in June and never in December.

Or did you need the math?

Answer 7

Call a friend who is 3000 miles away and ask him where the sun is in the sky. Tell him to measure the angle up from the horizon. Then do the same where you are at the same time. Even better, take a time lapse photgraph of the area of the sky near the North Star. All the stars will make circular paths around the North Star. Or you could just read a book.

Answer 8

lol...ok im thinking this is a question asked out of need to ask a question. In this day and age how can you not know it is round.
Common sence if nothing else look up in the shy see the moon?
Im thinking youmean by proof is how can you see it is round. Guess you could buy a ticket on the next shuttle.lol If the proof you request is visual confirmation that is. But serriously with all the basic understanding of tides earth rotation and gravity you have your proof.

Answer 9

It's very close to being a sphere.
I'm willing to take the word of the Russian astronauts, who orbit the Earth in the Mir space station, and have seen the whole world through their windows.

Answer 10

classical examples are

misuration of the earth circumference by Eratosthenes ~200 BC
the Foucault pendulum experiment 1851
the earth shadow during the Moon eclypse is round (Mesopotamian times 3000 BC)

Answer 11

the earth's shadow does not make the moon go through its phases, it is the moon shadowing itself.

during a lunar eclipse however the earth's shadow is curved and you can easily tell that with your own eyes, unlike pictures and whatnot which could have been faked (just in case you're the paranoid type)