The Earth is mostly spherical.

I'll attend to the opponent's case, then defend my own. 1. Distances sighted.In the video provided, we see that the skyline flits in and out of existence, despite the weather remaining nominal. If this were not a mirage, the image should not appear, disappear and reappear again in the manner that it does. Mirages occur when the temperature of the ground is warmer than the temperature of the air above it. Since light travels at different speeds in different temperatures of air, a refraction takes place that causes images to be seen when no object exists there. "Night time" mirages can occur, especially near bodies of water which have retained the heat of the day.[1]Given this, there is no scientific reason the image cannot be a mirage. More importantly, we know that photographs have been taken of the skyline (like I provided in R2) in which the mirage was in its more typical, inverted form. The opponent has failed to explain how it is possible to take said photo under the flat earth model.2. Reflection of Light on WaterThe opponent basically says that the sun's reflection should look "completely different" on the curved surface of the ocean. This is unsubstantiated, however. Looking even at the image provided by the opponent, it is clear that the reflection of the sun does not look like the sun itself, but is minorly stretched.Subtle stretching is exactly what one would expect to see from a reflection occuring on a slightly convex surface. Note the image I provided and how it demonstrates the way in which light rays hit the ocean and reflect into one's eyes.The "experiment" posted by the opponent doesn't seem to prove anything. The images look very similar, but that is because reflections still occur regardless of how curved a reflective surface is. The magnitude of the curve represents the magnitude of the "stretching" of the image. In Earth's case, the magnitude of curvature is very small. 3. Flight PathsFuel: This example was to prove that not all straight flight paths are feasible. With the particular example of Chile and Sydney, fuel may not need to be a significant consideration. Economic efficiency: To answer the opponent's question -- yes, it is more feasible to travel twice the difference to pick up new passengers. A Boeing 747 costs about $140,000 to fly its max distance of 6,000 miles. The distance from Sydney to Chile is about 7,000 miles. This necessitates a flight stop, and will cost about $160,000.Sydney --> LAX is about 7,500 miles. LAX --> Chile is 5,500 miles. This puts the total flight distance at 13,000 miles, which is indeed nearly double. This means the fuel cost is around $320,000.A plane ticket for that distance is about $1,000, meaning that a direct Sydney --> Chile flight would require 160 people for the airline to break even. There simply are not enough people who want to make this flight. The are significantly more people who want to go from Sydney to the US though. From there, a new set of passengers can leave off to Chile. Ie, you can get three to four times as many passengers by travelling the extra distance, meaning that you can get significantly more profit. GyroscopesThe "basic" gyro behaves like a space-gyro, in that it will maintain its position. An "earth-gyro" is a more complicated device and is often called a attitude indicator. It is essentially a gyroscope that contains a "pendulous rod" (pendulum) at the bottom. [2] This weighted bottom effectively locks the horizontal plane of the gyroscope perpendicular to the direction of downward force (gravity). The weight of the pendulum is greater than the amount of angular momentum that is conserved, thus insuring that the gyro remains level with the horizontal plane. So, to simply answer the question -- a space gyro does not have a pendulous rod, an earth gyro does. Defense1. SatellitesThe opponent has a few claims as to why he believes satellites are a myth. I'll address each. The ISS tracking sites change the position of the ISS if you change date/time on your computer.Well, yes. The (quite simple) mathematics behind orbiting objects allows one to know exactly where a satellite is if you know its orbit and its position at even one time in history.Therefore, if you know the nature of the orbit the ISS is on (we do, since we set it into that orbit) and its position at at least one point in time (again, we do) -- you can calculate its position at any other time. If you change your computer time to May 16th, 1995, the program will tell you where the ISS was at that time. The ISS looks kind of like a U2 plane. I mean, I don't think it does. There is a clear difference between the satellite in the pictures the opponent provides and the U2 plane. The shape of the vessels are entirely different. More importantly, we have amateurs who have taken very detailed shots of the ISS. [3] In these photos the ISS looks exactly as the ISS is purported to look and noticeably looks nothing like a plane. Why can you see the ISS if it's so far away?The opponent says that passenger jets only 7 miles away look very smile, whereas the ISS can clearly be seen as a dot of light. The simple answer is this -- one is reflecting large amounts of light, the other is not. The ISS has very large solar panels that reflect great amounts of light, whereas passenger jets generally consist of non-reflective material. The slightly more complicated answer is that an object's apparent size decrease is inversely porportional to its distance away. In other words, if you move an object 10 m from you and it appears to get 3mm smaller, moving it another 10 meters away will yield an apparent size change of less than 3 mm. Even though the ISS is 20 times further than a passenger jet, it will not appear 20 times smaller. It should be too hot for satellites. Again, simple answer -- radiators. More complicated answer -- the thermosphere is hot. Ab object will absorb radiated heat to a point, then radiate excess heat outward. This occurs once a certain temperature is reached, called the "radiative equilibrium temperature". When you put a radiator on an object, you effectively lower this temperature, since the object is capable of radiating more heat. All artificial satellites have built in radiators. The ISS in particular has radiators on the backside of the large solar panel arrays. This allows them to not melt or burn despite the heat of the thermosphere. Entire books have been written on the subject [4], as heat management is important in any mechanical system's design. Cell towers are sufficientI made a mistake here earlier. Cellular service only uses towers. Satellite phones use satellites. These are wide spread enough such that anyone could use them and many do use them. They would not be able to function without satellites (like how they can function in the middle of the ocean.) Without satellites, this functioning would be impossible.2. Aerospace TextbooksThis point isn't empircal -- but it is entirely logical. What's more, it's relatively easy to understand the basics and any voter could easily see how the basic pillars upon which aerospace is taught assume a spherical earth. The opponent basically says next that launched satellites actually go into the Bermuda Triangle. This is one of the few points I will not entertain without evidence or logic to support it. The claim is ludicrous and needs to be proved or it will continue to be considered ludicrous. The opponent then asks why rockets wait to turn until they are miles above the earth. The answer -- it is more efficient to do it this way. When you turn in the lower atmosphere, you will necessarily spend more time there, incurring all the wastes of friction caused by the atmosphere. If you wait until you are in a thinner atmosphere, you are able to turn and get into orbit using less fuel. Fuel is a huge concern in rocket design. 3. Time zonesThe opponent claims, without evidence, that a distant sun should cause a uniform temperature on Earth. Basic principles of physics show this to be untrue. The sun heats the Earth entirely via radiation, since the other two forms of heating (convection and conduction) require a non-vaccuum. Clearly when one side of the earth is facing the sun, it is being irradiated, whereas the non-lit side is not being radiated. If one section of the Earth (like the equator) faces the sun for a greater percentage of the time than another area (like the poles), you'll find that the more-lit section will generally be hotter. This makes sense, consideration it receives greater radiation than non-lit areas. Summer and winter only exist because hemispheres receive different amounts of sunlight over the year. This is why winters have longer nights -- less sun is received. The next claim is that the sun shrinks when heading toward the horizon. The only evidence for this is a video. Please note that it is impossible to "eyeball" the actual size of the sun during the day, since it is so bright that lens flare (eye lens) can look like part of the sun. As the sun sets, you see less of its light (since it is largely being absorbed by the atmosphere), reducing the lens flare and leading one to see the actual boundaries of the sun. The opponent literally offers no empirical evidence that the sun is very close to the Earth. ConclusionI've demonstrated the flaws in the opponent's case and corrected his misunderstanding regarding my own. I look forward to the next round. Sources: 1 -http://www.seagrant.umn.edu...;2 - http://www.experimentalaircraft.info...;3 - http://blogs.discovermagazine.com...;4 - https://books.google.com...;