ion of rotation changes from the Northern to the Southern Hemisphere, is sufficient to demonstrate the qualitative effects of the Earth’s rotation.
However, most of these difficulties can be avoided if one substitutes a gyroscope for the pendulum. With a high-quality gyroscope one can minimize several sources of error. The gyroscope will rotate clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere. One does not need to observe a complete rotation of the gyroscope, one simply needs to observe the amount of rotation and determine that the angular speed ω is as determined by our formula.
Flat Earther Bob Knodel has achieved notoriety for his “Globebusters” YouTube videos. A scientific debunker who runs the Web site “Flat Earth Lunacy” challenged Knodel to purchase a high-quality ring laser gyroscope, to carry out measurements that would show the Earth’s rotation. A paper by Beverini et al. discussed how one could measure the Earth’s rotation with this instrument.
Apparently Knodel purchased a ring laser gyroscope, with the aim of demonstrating that the Earth does not rotate. According to the Debunking Flat Earth Misconceptions Web site, Knodel’s measurements indeed demonstrated the Earth was rotating at an angular rate of 15o/hour (one full rotation per day). Furthermore, the gyroscope showed rotation in the “correct” direction (a specific direction in either Hemisphere). It is claimed that Knodel refuses to publicly announce the results of his gyroscope test until he can produce the “correct result” (i.e., a stationary Earth). This shows the lengths to which Flat-Earthers are willing to go to maintain their predetermined conclusions. They have no interest in actually obtaining the correct result, or in minimizing errors in their measurements. Any result, no matter how crappy, that is consistent with their Flat-Earth biases is accepted, while they go to incredible lengths to “explain away” anything that demonstrates the motion of the Earth.
II.6: Size and Distance of the Sun
Flat-Earthers claim that the Sun is only about 3,000 miles above Earth, rather than 93 million miles as determined by astrophysics. Furthermore, the Flat-Earth Sun is only 32 miles in diameter, rather than 864,340 miles in conventional astronomy. Let’s discuss some of the evidence that the Sun is extremely large and very far away.
First, we consider the classic experiment carried out by the Greek scholar Eratosthenes in 205 BCE to estimate the circumference of the Earth. Eratosthenes noted that there was a day when the noonday Sun was directly overhead in Syene (modern-day Aswan, Egypt, at 24º N latitude). Since the Sun’s rays are traveling straight down relative to Earth, a pole in Syene will have no shadow at that time. However, in Alexandria (31º North latitude), poles would produce a shadow at the same hour. Eratosthenes assumed that the Earth was a sphere; he further assumed that the Sun was sufficiently far from Earth that one could approximate the Sun’s rays as reaching Earth on parallel lines. From the measured shadow length in Alexandria and some simple geometry to deduce the angular difference of the Sun’s rays between Syene and Alexandria, Eratosthenes estimated the radius of the Earth as roughly 4360 miles, which is about 10% larger than modern measurements of Earth’s radius.
Flat-Earthers point out that Eratosthenes’ experiment does not prove that the Earth is a sphere. This statement is true – Eratosthenes assumed that the Earth was spherical, and from that assumption he calculated the Earth’s radius. Flat-Earthers state that they can repeat the measurement of Eratosthenes, assuming the Earth is flat. The “Flat-Earth” measurement is shown on the left side of Fig. II.16, in contrast to the “spherical Earth” measurement on the right side. In fact, this is how some Flat-Earthers derive the distance to the Sun; they repeat the Eratosthenes measurement in Flat-Earth geometry and obtain a distance of roughly 3,000 miles.
This statement works for measuring shadows at 2 points in Egypt, Syene and Alexandria. However