Shanghai, China and Buenos Aires, Argentina are a near antipodal pair. Both are located at the diametrically opposite points to each other on Earth’s surface. Therefore, we can fly from Buenos Aires in any direction and arrive in Shanghai after traveling a roughly similar distance, regardless of the course taken.
Any flight between an antipodal pair has a similar duration even though the different flights have different directions. This fact is only consistent with spherical Earth and cannot possibly be explained if Earth is flat.
Continue reading “Antipodal Flight: Shanghai–Buenos Aires”
Some flat-Earthers noticed some flights from Perth to Johannesburg have a flight change in Dubai. They use the fact to ‘prove’ a flat Earth. In reality, there are non-stop flights of the same route that are impossible to explain if the Earth is flat.
With a flight change in Dubai, the flight takes more than twice as long, as Dubai is nowhere near the non-stop flight path. In fact, Perth–Dubai is a longer hop than the direct Johannesburg–Perth route. These are consistent only with a spherical Earth and can never be explained if the Earth is flat.
Continue reading “Perth–Johannesburg Flight Route”
In making mathematical models, physicists often remove real-world details that have little influence over the final results for simplifications. In flight-dynamics, it is often perfectly adequate to assume Earth is flat & non-rotating, even if the aircraft is flying over spherical & rotating Earth.
Some flat-Earthers claimed to have exposed ‘a secret document’ from NASA saying that Earth is flat & non-rotating. They are wrong. The document is simply a derivation of a flight dynamics problem, assuming flat and non-rotating Earth, which is a common assumption made to simplify flight models. It does not imply the Earth is flat and non-rotating.
Continue reading “Flight Dynamics: Simplification by Assuming Flat & Non-Rotating Earth”
There are several time-lapse videos taken on board of a New York – Moscow flight, looking northward through a window on the left side. In the videos, the sky never looked fully dark, and the sun was visible most of the time on the flight.
Flat-Earthers erroneously assumed that the phenomenon is not possible if Earth is a sphere and that it is “evidence” the Earth is flat. In reality, everything in the videos can be easily explained and is fully consistent with the spherical Earth model.
Continue reading “New York JFK – Moscow SVO Flight Time-Lapse Videos”
When aboard an airplane flying at cruising speed, we will not be able to feel that the plane is, in fact, moving at speed of more than 900 km/h. But if the plane changes its speed, turns or changes its altitude, we can easily feel it.
The same thing happens with the motion of the Earth. Due to Earth’s rotation, the surface of the Earth is moving at 1656 km/h near the equator. We never feel it because the speed is constant, or in other words, the acceleration is zero.
Continue reading “Human Perception of Speed and Acceleration”
An airplane exists on Earth. It has the same motion as the surface of the Earth, including the Earth’s rotating motion. The motion of the airplane itself is measured relative to the surface of the Earth.
Flat-Earthers think that due to Earth’s rotation, an airplane should not be able to fly east or land. They are wrong. The speed of an airplane is relative to the surface. It retains the motion of the Earth and does not need to chase Earth’s rotation.
Continue reading “Airplane and Earth’s Rotation”
The cruising altitude of a jet airliner is about 33000-42000 ft or 10000-12800 m. It is very tiny compared to the radius of the Earth of 6378 km. Therefore, the distance measured at the cruising altitude does not differ much compared to the surface distance.
Some flat-Earthers claim that if Earth is a sphere, the distance traveled by a jet airliner would have been multiple times the surface distance. They are wrong. The air distance at 33000 ft is only 0.16% farther compared to the surface distance.
On many flights, they would give away leveling devices to all passengers for free, so that everyone would be able to observe the dip of the horizon and proves Earth is a sphere. And as a nice side effect, to quench our thirsts, too!
Such devices are called ‘bottled water’. Using these simple ‘instruments’ on a flight, we can demonstrate that Earth is a sphere.
Continue reading “Bottled Water: A Simple Device for Observing the Dip of the Horizon”
Earth’s curvature is hard to observe from the surface. Even from the altitude of a commercial passenger flight, about 30000-40000 ft, Earth’s curvature is still too small to notice. However, under careful observation, it is not impossible to confirm the curve from the cruising altitude of a jet airliner.
Continue reading “Observing Earth’s Curvature on a Flight”
A ring laser gyroscope (RLG) is an instrument for measuring the change in orientation and rotational velocity. It is sensitive enough to measure Earth’s rotation easily.
Flat-Earthers claim that there is no instrument able to measure Earth’s rotation. Such claim arose from their ignorance. Ring laser gyroscopes —which are installed in some airplanes and ships— can easily detect and measure Earth’s rotation.
Continue reading “Ring Laser Gyroscopes are Sensitive Enough to Measure Earth’s Rotation”
A frame of reference consists of an abstract coordinate system and the set of physical reference points that uniquely fix the coordinate system and standardize measurements. Speed or velocity is relative to a frame of reference. It is possible that two speeds/velocities are measured relative to a different frame of reference and thus cannot be directly compared.
Flat-Earthers would often compare two different speed measurements like an airplane moving at 900 km/h (560 mph) and Earth’s surface near the equator at 1674 km/h (1040 mph). They would conclude the airplane should not be able to catch up with Earth’s surface and would not be able to land if the Earth is rotating. They are wrong. The speeds are measured relative to the different frame of reference, and therefore, cannot be compared directly.
Continue reading “Frame of Reference”
Earth’s atmosphere is part of the Earth. It practically follows Earth’s rotating motion like the rest of the Earth. Due to various factors, Earth’s atmosphere has relatively small and uneven movement relative to the surface. We call it ‘wind.’ The fastest wind ever recorded is about 408 km/h, relative to Earth’s surface.
Many misconceptions about Earth arise from the wrong idea that only Earth’s solid body is rotating, but the atmosphere is not. If it is true, then we should always feel the wind with the speed of 1674 km/h near the equator, or more than 4× the fastest wind ever recorded. We don’t feel such a wind, and thus we know our atmosphere is moving at practically at the same speed as Earth’s surface.
Continue reading “Earth’s Atmosphere Rotation”
There was a flight from Taiwan to Los Angeles that was diverted to Anchorage because one of the passengers gave birth to a baby. Flat-Earthers use the case as one of the first “evidence” from flight routes proving Earth is flat.
They are wrong. The case only tells us about the ignorance of these flat-Earthers about the distortion in a map projection. Their argument started with an elementary mistake of taking a straight line on a Mercator map between Taiwan and Los Angeles, and assume it as the “intended flight path.”
Continue reading “The Taiwan–Los Angeles Flight (not from Bali) that was Diverted to Anchorage”
We cannot travel to another location by hovering inside a helicopter and wait for the Earth to rotate below us until we are above our destination. The reason is the phenomenon of inertia.
Flat-Earthers claim that we cannot do such a thing as ‘proof’ of a motionless Earth. They are wrong. When on the ground, the helicopter itself is already moving at the same velocity as Earth’s surface.
Continue reading “Helicopter and Earth’s Rotating Motion”
The perpetrators of flat-Earth often take emergency landings as ‘proof’ of a flat Earth. They would point out that the diversion airports used for such emergency landings are somehow consistent with the flat-Earth map.
It is not a coincidence that all the cases of emergency landing they pointed out occurred far in the north. At the locations closer to the north pole, the distortion of the azimuthal-equidistant map (claimed by flat-Earthers as the ‘flat-Earth map’) diminishes. It would seemingly appear as if the ‘flat-Earth map’ can explain the choice of the diversion airports. In many other locations, though, the flat-Earth map would fail to explain it.
Continue reading “The Failure of Flat-Earth Model to Explain Emergency Landings That Occur More to the South”
Drag is a force acting opposite to the relative motion of an object moving with respect to a surrounding fluid. The higher the density of the fluid, the higher the magnitude of the drag.
Flat-Earthers claim that it is impossible for satellites to have such high speed. Usually, they would compare the speed of satellites to something like the SR-71 Blackbird, which holds the record as the fastest aircraft. They are wrong. At the altitude where satellites reside, the air density is several magnitudes smaller compared to near the surface, and thus, the drag experienced by satellites is also several magnitude smaller.
Continue reading “Drag”
An AEW&C (airborne early warning and control) system is a radar system attached to an aircraft. It can detect objects at a very long range compared to any surface mounted radar system.
The reason is that Earth’s curvature limits the range of a surface-based radar. An airborne radar system mitigates this problem.
Continue reading “Airborne Early Warning & Control (AEW&C): Mitigating Limited Radar Range Due to Earth’s Curvature”
The GPS system is one-way. The satellites broadcast signals. GPS devices receive and process the signals to determine their location.
Flat-Earthers often point out the fact we were unable to locate the ill-fated MH370 as ‘evidence’ GPS doesn’t work and therefore doesn’t exist. They are wrong. GPS satellites never receive any signal from GPS devices, and it is not possible for them to locate MH370.
Continue reading “The MH370 Disaster and the Inability of the GPS System to Locate It”
We can use the duration of a flight route to roughly determine the distance between two locations. Then, we can use this to determine which model better represents reality: the flat-Earth model or the spherical Earth model.
In the flat-Earth Model, the distances between two locations become more unreasonable as we go further south. To illustrate this fact, we can use the flight route of Sydney-Santiago to help us with the calculations. This flight route is one of the most southernly flight routes. Continue reading “The Sydney-Santiago Flight Route: An Impossible Route on the Flat-Earth Model”
Flat-Earthers think there hasn’t been anyone who has circumnavigated the Earth by traversing both the north pole and south pole in the process. All we have are explorers who have circumnavigated the Earth to the east or west, parallel to the equator; explorers like James Cook or Ferdinand Magellan. They don’t really have the choice, because if polar circumnavigation is possible, then the flat-Earth assumption falls flat.
But, like a lot of assumption in the flat-Earth community, it is simply not true. There are in fact many people who have done a polar circumnavigation, and the information can be easily found on the Internet.
Continue reading “Polar Circumnavigation”