The earth is a sphere

Firstly, Con questions why 'astronauts need glass and metal to keep the vacuum of space from sucking out all the air but our atmosphere just kind of sits on the vacuum with no interference'.Simply, the earth's gravity holds our atmosphere in, and is in equilibrium with the pressure gradient force that tries to suck our atmosphere out into the vacuum of space. Now I think about it, this is another proof that gravity exists; if it didn't exist, then we wouldn't have an atmosphere.PhotoshopI did look at the images, but I'll point out again that these are composite images that are put together in different ways and so some are bound to be distorted. This does not mean they are faked. The reason that most blue marble photos are composite photos is that photo satellites are relatively low altitude compared to most satellites and so are not high enough to take single-shot photos of earth. Of course we have satellites that can see the earth from far out enough to see the whole sphere, but these aren't photo satelites.Furthermore, nobody has claimed that there are satelites that are light years away. Our furthest satellite, Voyager 1, is a tiny fraction of that distance away (1).Next, Con asks why someone cannot take 'real, non composite images of earth'. Well, someone already has, from the moon (2) and the Russians have taken a single shot image as well, which is far too detailed to be faked. (3)Also, he queries why there are no videos of the earth rotating. Again, videos do actually exist. (4)In regards to copy and pasting of clouds, I'm afraid I cannot accept that argument unless it is shown to be an actual, undoctored photo from NASA.About letters in clouds, they must exist due to probability. Words aren't that complex patterns (especially short ones like sex) and clouds form a random shape. Considering the sheer quantity of clouds, it is inevitable that some will randomly look like words, just like some people see animals or symbols in clouds.Con's next statement is that 'there are said to be thousands [of satellites], surely some of them would show up'. This is a fallacy. If something is comparatively too small to be seen, then adding a few more won't make them more likely to show up (admittedly, at some point they will become so densely populated that they will blot out parts of the earth, but there are not nearly enough satellites for this to happen). For example, if I put a piece of dust on a cinema screen it won't show up. Even if I put thousands of specks of dust on the screen, it still won't show up. Their insignificant size as well as the fact that the earth is reflecting huge amounts of light both contribute to the lack of satellites we can see in earth photographs.Finally, the Russian photograph's colour is slightly different because their photos also capture infrared light, which is why the plants look rusty red (3). This does not by any means constitute proof that the photos are fake. It even implies that they are real, since a faked image would look exactly what we would expect it to look like.CircumnavigationCon has conceded this argument because he has dropped it. Since it has gone unopposed, it assumes de facto veracity and will fulfil my burden of proof if it remains unrefuted.GravityThe reason that dense things sink in relation to less dense things is because of gravity! What other force would pull dense things down? If we had a vacuum containing a mixture of oil and water in outer space (two liquids with differing density), the water would not sink below the oil despite being denser. Why? Because of Newton's first law. Something will not accelerate (i.e move from a stationary position) if there is no resultant force acting upon it. In space, there is no force so the water will not sink. But on earth, the water does sink. What has changed between the two scenarios? The introduction of a gravitational force. In conclusion, empirically we can observe that it is gravity that causes denser matter to sink below less dense matter.You don't need a rigorous test to empirically prove that gravity exists. Just jump out of a plane. If gravity does not exist, you will not fall (since there is no resultant downward force). But you do fall. Therefore gravity exists (unless there is some other force that causes you to fall, but none have been suggested as of yet).The earth has not collapsed in on itself because it is not hollow. There are thousands of miles of rock, magma and iron between the earth's centre of gravity and the surface. It cannot collapse in on itself because, 1, the gravitational force isn't strong enough and, 2, there are billions of tons of rock and iron between the core and the surface. It's in the way.GyroscopesI'll forget this argument because I honestly don't know enough about gyroscopes to debate about their activity. Nevertheless, my burden of proof is still firmly established in my other arguments.Dipping distancesCon's source does not give data that entails that a lighthouse would be visible beyond the horizon. I even calculated some of it myself (I'm a student of marine navigation) and found nothing that refutes the notion of a curved surface of the earth.The Japanese laser being seen in Chicago is not backed up by either one of Con's source. His first source said that a green light was seen in Chicago and his 2nd source states that green laser was tested in Japan; it doesn't follow that the sources are referring to the same light.Granted, the atmosphere is thicker at lower altitudes. But why is this relevant? Visibility is lower at higher altitudes (due to more air having been cooled below its dew point) which is what I presume Con was trying to argue. In other words, the 'air being thicker at lower altitudes' does not entail that it is beneficial to build tall lighthouses. Lighthouses were built higher so they could be seen from further away (5).The law of perception only limits how far we can see because our eyes cannot render an image of something very far away, if we had a powerful telescope and pointed it east from Shanghai, we would be able to see California if the earth was flat. Since we couldn't manage to see California even with a very powerful telescope, it follows that the earth cannot be flat. The law of perception only entails that our eyes cannot see something distinctly from a long distance away, this is mitigated if one uses a powerful telescope.The video Con cites that allegedly proves that some things can be seen through a telescope that should be beyond the horizon does nothing of the sort. Nothing within that video backs up that assertion.High photosRegarding Felix Baumgartner, I do not deny that GoPro lenses can bend the image of the earth. But for the vast majority of the video the earth was shaped as a sphere, only occasionally being concave. This suggests that the earth is a sphere and the concave earth is an anomaly caused by the lens.I watched Con's videos of the amateur balloon flights. Both of them show a very slight curvature of the earth (just place a ruler on the computer screen). They are also not high enough to start seeing a noticeable curve.StarsYou can prove that the stars are trillions of miles away. First we can measure the sizes of stars using stellar interferometry (6) and we can tell their temperature by observing the wavelength of the colour light they radiate and using Wien's Law (WT = 2.898 × 10^–3 m K), where T is temperature and W is the wavelength of the star's colour. Since we know temperature and diameter, we can find a star's luminosity using the Stefan Boltzmann law (L = sigmaT^4.A)(8) and then compare it to the luminosity we observe on earth to find the distance away (F = L/ï¿½pi.d^2 )(9). This proves that stars are trillions of miles away._____(1) http://go.nasa.gov...(2) http://bit.ly...(3) http://bit.ly...(4) http://bit.ly...(5) http://bit.ly...(6) http://bit.ly...(7) http://bit.ly...(8) http://bit.ly...(9) http://bit.ly...