Weird Earth. Donald R. ProtheroЧитать онлайн книгу.
the Big Dipper, which dominates the night sky above forty-one degrees north latitude, vanishes below the horizon as you head south, so at about twenty-five degrees south latitude in northern Australia, it is gone from the sky.
3. Watch a lunar eclipse: Every few years, we experience a lunar eclipse, where the disk of the full moon is covered by the shadow of the earth. It’s weird to watch the circle of the moon gradually get darker and darker as the edge of the earth’s shadow gradually covers it (fig. 2.4). As first discovered by the ancients and reported by Aristotle, the edge of earth’s shadow is unmistakably curved and becomes even more so as the eclipse approaches totality. Finally, the earth’s shadow covers the moon completely, so the only moonlight you see is from light that has passed around the curve of the earth and through our atmosphere (turning it red), refracting to the middle of the shadow.
Many times, the lunar eclipse is not total, but as the distance of the earth from the moon increases, it casts a slightly smaller shadow and the shining edges of the moon are visible on the edge of the shadow. This is called an annular eclipse, and it shows the entire shadow of the earth as a circle or ring of light around the dark shadow. This would never make sense if the earth were flat. Flat-earthers claim that the sunlight is blocked by the flat circular disk of the earth, but why then does the sun never happen to catch the flat disk of the earth on its edge or at an angle, so the shadow has a shape other than a circle? The only way this is possible is if eclipses happened only at midnight, when the “flat disk” is perpendicular to the sun-earth axis, so the “dark side” of the earth would only see the total eclipse of the moon when it was directly overhead at the stroke of midnight. In fact, lunar eclipses happen at all different times of day and night (although they are not very visible in the daytime).
Figure 2.4. A total lunar eclipse on June 15, 2011, as seen from Budapest, Hungary. The upper left frame shows totality, with the moon entirely covered by the earth’s shadow. Over the next hour, the earth’s shadow moves off to the lower right, and its distinctly curved edge can be seen, showing that the earth casts a curved shadow and therefore must be a spherical shape. By 23:10 Universal Time, the shadow has almost completely vanished and the full moon is visible. (Photo courtesy Wikimedia Commons.)
4. Go climb a mountain: If the earth were flat, you could see huge distances if you had a good enough telescope, so looking across the distance between Miami and New York City, only 1,000 miles or 1,760 kilometers, should be no problem. But if you are standing on level ground, even under the best of conditions with a superpowerful telescope, you can see no farther than about 3 miles (5 kilometers). Any object farther than that disappears below the horizon. Of course, if you climb a tree or even a mountain, you can see a bit farther on a day with excellent clear air and visibility. Standing on a hill 60 meters high, you can see about 50 kilometers. But even from the tallest mountains, no one can see much farther than about 60 miles or 100 kilometers, certainly not the distance from New York to Miami.
Take another example: Mauna Kea volcano on the Big Island of Hawaii is the highest peak in the Hawaiian Islands at 4,205 meters (13,796 feet). On a flat earth with nothing but ocean for many miles, you should be able to see enormous distances on a clear day. On the island of Kauai, only 487 kilometers (303 miles) away, is that island’s highest peak, Kawaikini, at 1,592 meters (5,226 feet). Over such a short distance on a flat earth, someone on Mauna Kea should easily be able to see the top of Kauai, but you can’t, because the earth is curved. Thanks to that curvature, the farthest you can see from Mauna Kea is 374 kilometers (233 miles).
5. Go fly in a plane: If you fly around the world, you 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