are traveling around a sphere. You cannot do this on a disk-shaped earth. If you calculated the distances to travel in a circle around the North Pole on a disk-shaped earth (fig. 2.2), it would not add up to the distance you must actually travel around a spherical globe, no matter which latitude you traveled along. Even more convincing is the view from high above the earth. Unlike the people like “Mad” Mike Hughes who killed himself in his homemade rocket that rose only 1,875 feet, there are ways to get high enough to see the earth’s curvature. In a passenger jet flying above 35,000 feet, the curvature begins to be visible, although you need a wide window with a sixty-degree field of view to detect the curvature.
This isn’t possible to see with the tiny passenger windows, but the crew on the flight deck can see it fine, so anyone in the cockpit in flight can see it. (Sadly, after the 9/11 hijackings, the flight deck is always locked against intruders during flight.) Above fifty thousand feet, the curvature becomes more obvious, although few commercial aircraft fly that high. The now-retired supersonic Concorde jet routinely cruised at sixty thousand feet, so passengers on those flights could see the curvature of the earth easily. And of course, military aircraft and spacecraft and our thousands of satellites fly much higher and see it all the time, but as flat-earthers believe that everything from NASA and the military is part of great conspiracy to hoax us all, that won’t help convince them.
6. Fly near the South Pole: Flat-earthers claim that there is no South Pole or Antarctic continent over it, but just a 1,500-foot-tall ice wall around the edge of the earth’s disk guarded by NASA (fig. 2.2). According to the Flat Earth Society, no one has been past this ice wall and lived to tell the tale. Of course, this makes everyone who has ever traveled to Antarctica a hoaxer and liar, including pioneering polar explorers like Roald Amundsen (who reached the South Pole first), Ernest Shackleton, Sir Robert Scott, and others who made these expeditions before the flat-earth idea of the ice wall had been suggested. It also makes liars out of anyone else who may have traveled across the Antarctic Circle and returned successfully, or all the polar researchers down in Antarctica right now. (I have several friends down there finding fossils as I write this.)
Despite what flat-earthers claim, commercial flights do travel over part of the Antarctic,35 and if you get the right window seat and good weather during these flights, you can see parts of Antarctica from your seat. Most commercial flights across the Southern Hemisphere don’t fly over the center of Antarctica because it is not on the shortest possible route (the great circle route, or the straightest line on a globe) between South America and Australia, or South Africa and Australia. But they do fly over the edge of the continent, so you could look down and see the Antarctic ice sheet from your window seat.36 A flight between New Zealand and South Africa would cross Antarctica, but currently there are no flights scheduled to do this.37 Anyway, a commercial flight over the ice cap is not a good idea, especially given the bad weather over Antarctica most of the year—and also because if they have plane trouble, it’s much better to make an emergency landing in the Southern Ocean where there is a chance of rescue rather than in the middle of the Antarctic ice cap. Flights that run south of seventy-two degrees south latitude must carry special survival gear in case they go down in the polar region. As this regulation reduces the number of paying passengers they carry,38 not many flights are scheduled in the Antarctic Circle.
7. Send up a balloon: Another way to get your own images from high enough to see the earth’s curvature is to send up a weather balloon. Both balloons and the kinds of cameras and equipment needed to record and transmit the signals are easily available through commercial sources now, for anyone who has the technical skills and funds to try this. In January 2017, a group of students from the University of Leicester Department of Physics of Astronomy and members of the Leicester Astronomy and Rocketry Society did just such an experiment. Their weather balloon, launched from Tewksbury in Gloucestershire, rose 77,429 feet (23.6 kilometers) into the sky, and their cameras sent back stunning footage of the curved earth from the high atmosphere (fig. 2.5).39 You are welcome to watch the footage online for yourself (just search for videos under “Project Aether”) and see it vividly demonstrating the view from higher and higher elevations. After reaching its maximum altitude (where the temperature was about–56° Celsius and the air pressure was nearly a vacuum), the payload then descended to earth at speeds of more than 100 miles per hour and was successfully recovered in Warwickshire. You can try it yourself if you have the money and the expertise! Just contact the Federal Aviation Administration before you launch to make sure that your balloon doesn’t fly into restricted airspace.
Figure 2.5. Image of earth from balloon. (Courtesy Wikimedia Commons.)
8. Compare shadows: If you are motivated, you can replicate Eratosthenes’s famous experiment (fig. 2.1) yourself. The simplest way to do it would be to take a long flight in a north-south direction. Before you take off, measure the length your shadow casts at a particular time of day at your starting point. Take the flight, and then at the same time on the following day, measure the shadow at your new location. It should be measurably longer or shorter if you have traveled far enough. If the earth were a flat disk and not a sphere, this would not happen, because the sunlight coming in at an angle on a flat disk would always cast the same length of shadow.
9. Compare time zones: As anyone with jet lag can tell you, traveling east to west, or west to east, around the earth for any significant distance is discombobulating, because changing time zones upsets your biological clock. This is a direct demonstration of how different parts of the spinning earth are facing the sun at different angles, so they are all experiencing a different time of the day relative to the sun. The easiest way to confirm this in this world of instantaneous satellite communication (which in itself is a confirmation of the spherical earth) is to compare the time you are experiencing in your area with the time of someone in a different part of the world. For example, if it’s noon in New York and you email or text or call a friend in Beijing, it’s midnight there, and it’s 1:30 a.m. in Adelaide, Australia. Or if you look up the times for sunrise and sunset at different longitudes around the earth, you see that they occur at different times. This is simply impossible with a flat earth. Flat- earthers have tried to get around this problem by claiming that the sun’s light casts a big circular flat “spotlight” that is pointing in a circle around the different parts of the earth, but that explanation falls apart if you think about it. If you were in a large darkened theater, you could still see the spotlight casting its light on the stage even though you might be in total darkness where you sit.
10. Compare seasons: If the earth were flat, the sun’s rays would hit all parts of the earth from straight above and would not come in at an angle, like they actually do. In addition, there would be no seasons, because on a flat earth, both the Northern and Southern Hemispheres would get the same amount of solar radiation all year round. We would all experience whatever seasons there were the same way. But thanks to the spherical shape of the earth and its tilted axis, we experience seasons at different times, so winter in the Northern Hemisphere is summer in the Southern Hemisphere, and vice versa.
11. Feel the pull of gravity: If you accept the laws of gravity worked out by Isaac Newton, then the force of attraction of gravity should get stronger the closer you are to the center of mass. In a flat-earth disk (fig. 2.2), gravity should be strongest in the center of the disk at the North Pole and much weaker as you approach the Antarctic, on the edge of the disk. If you dropped an apple in Australia or southern Patagonia, it should fall somewhat sideways, pulled toward the North Pole, not straight down—but it doesn’t. Anyone with a decent gravimeter (a device that measures gravitational
