A point source is a source or reflection of light with a smaller angular size than the angular resolution of the observer. It is visible as a bright dot if bright enough against a dark background but not resolvable, or no detail is discernible.
Flat-Earthers claim the ISS should not be visible like a distant plane is not visible. In reality, aircraft lights can be seen from 60 km in a dark sky but are not resolvable. We can see them because they are point sources on a dark background.
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We can observe satellites with the naked eye, and they will appear like fast-moving stars across the sky. The required conditions: the satellite is large enough and/or close enough, the sky is dark enough, and the satellite is lit by the sun. As a result, the best time to observe satellites is a few hours before sunrise and a few hours after sunset.
Flat-Earthers claim it is impossible to see satellites and use the fact as “proof” the satellites do not exist. In reality, we can observe the satellites even with the naked eye. Apps and websites like heavens-above.com provide us with information on satellite watching opportunities.
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A human eye can only visually perceive the curvature of the Earth if we are at a considerable altitude from the surface, which is still beyond the reach of most humans today. A commercial jet airliner is the highest position realistically attainable by most humans today. We can only perceive very slight curvature at such altitude and, even then, only in an ideal condition.
The basis of flat-Earthers’ belief is that the horizon appears flat. They would say if we cannot see the curvature, then there’s no curvature, and therefore, the Earth is flat. In reality, only a few people can travel high enough to see the curve. The highest we can realistically go is by getting on a commercial jet airliner, which can only go about 11-15 km up, only a fraction of Earth’s radius.
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Cameras with a fisheye lens are used in the ISS, high-altitude balloons, rocket bodies, and other purposes. The reason is that fisheye lenses have several advantages over rectilinear lenses.
Flat-Earthers claim there is an evil intention behind the usage of fisheye lenses. In reality, the use of fisheye lenses is not unreasonable. If it is desired to have a rectilinear image output, then it is not hard to defish fisheye images to rectilinear ones..
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A neutral buoyancy pool is a pool of water in which neutral buoyancy is used to train astronauts for the difficult task of working outside a spacecraft in a weightless environment. Some of these pools contain full-scale mock-ups of ISS modules and other spacecraft.
Flat-Earthers discovered videos of astronauts in a pool of water, and they jumped to the conclusion that it is how they faked videos of astronauts in space. In reality, these are videos of astronauts in a neutral buoyancy pool, in training for their upcoming mission to space.
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Stars are dim. We can only see them if our eyes are adapted for low light. Astronauts in space can see the stars when the sun is blocked from view and avoid seeing any large sunlit objects.
Some astronauts said they did not notice the stars, but others claim they could see them. Flat-Earthers use the conflicting statements to discredit spaceflight. In reality, sometimes astronauts can see the stars, and sometimes cannot, just like us on the ground, depending on the situation.
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Flat-Earthers compared the apparent size of the ISS and an airplane that appeared in photographs and then incorrectly concluded that the ISS could not be 410 km above us. Their mistake was equating altitude with distance and failing to account for both the ISS’ and the airplane’s downrange distance.
If an airplane is at an altitude of 12 km, it does not mean its distance from an observer is also 12 km. Its altitude and distance are equal only if the airplane is directly above the observer. If the plane is not directly above, then its distance is greater than its altitude.
Continue reading “ISS Size Compared to an Airplane in a Photograph”
Many space missions use animations to visualize the state of the missions because it is impossible to record a video of the event. Spacecrafts continuously send telemetry data to Earth informing the status of their mission, and from the data, an animation can be constructed to illustrate the spacecraft’s current situation.
Flat-Earthers accuse that the animations are “proof” that the missions are faked. In reality, the animations are faithful depictions of the missions and are made to visualize the real state of the mission. Animations are used because it is not viable to send another spacecraft only to record a video of the mission. Furthermore, in the cases where the video is available, it is still too difficult for these flat-Earthers to accept reality.
The International Space Station (ISS) was not constructed overnight. It is built gradually, and new components are still arriving after more than 20 years since it was first launched.
The ISS is one of humankind’s greatest achievements, but there is no video showing its construction from start to finish. Flat-Earthers use the fact to “disprove” the existence of the ISS. In reality, the ISS was constructed gradually in years. There is no such video the same way there is none for New York City, for example. It does not mean New York City does not exist. On the other hand, we can find plenty of videos showing the assembly of its specific modules on the Internet. Continue reading “ISS Construction Video”
The Earth rotates only once every 24 hours. To notice the rotation of Earth in a video taken from space, we need to speed up the video so that it appears fast enough for us to notice it. We also need to make sure the video was taken from a spacecraft where its motion does not dominate over the movement of Earth itself.
Flat-Earthers claim that videos taken from space were faked because the Earth does not appear rotating. In reality, Earth rotates far too slowly to be casually seen without increasing the speed.
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It is possible to fly to space as a tourist as long as we are willing to pay a lot of money. There have been seven persons who went to space and paid the trip from their own pockets.
Flat-Earthers claim if the first human spaceflight was more than half a century ago, there should be space tourism by now. In reality, there were already several cases of space tourism, even if it is still beyond the reach of most people today.
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In orbit, objects are weightless because both the objects and the spacecraft have the same speed and direction, and both are affected by the same gravitational influence. We use the spacecraft as the frame of reference. Because the objects are not in motion relative to the spacecraft, they appear to float.
In Earth orbit, the objects are still affected by Earth’s gravity, but yet they float. Flat-Earthers use it to disprove spaceflight. In reality, the objects float because we are using the spacecraft as the frame of reference, which is also moving by the same amount and is affected by the same gravity as the objects themselves.
Continue reading “Weightlessness, Free Fall, and Microgravity”
Angular resolution is the minimum separation between distinguishable features in an image. Objects smaller than the angular resolution are indiscernible in the picture. The theoretical maximum angular resolution is determined by the diameter of the aperture of the optical instrument.
Flat-Earthers like to demand images of the lunar landers taken with a telescope as proof that the Apollo Moon landings did occur. In reality, no optical telescope on Earth is large enough to resolve the landers.
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Drag or air resistance is a force acting opposite to the relative motion of an object with respect to a surrounding fluid. The magnitude of drag is directly proportional to the fluid’s density.
Flat-Earthers claim that because satellites lack an aerodynamic shape, they cannot be faster than airplanes. In reality, the air density at such an altitude is minuscule and will not produce a significant drag. Thus, they do not need an aerodynamic shape.
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In 2006, astronaut Tim Peake from the UK was tasked to perform some physics demonstration on the ISS for the National Space Academy. Tim performed the demonstrations in front of a gridded background specifically made for the purpose.
One of Tim’s video appeared during the former US president George H.W. Bush’s visit to NASA’s Mission Control Center. Flat-Earthers discovered the footage and quickly claim that it used a green screen background for CGI purposes. Such allegation was only from their ignorance and the eagerness to accuse others of lying. Tim’s videos are published in the National Science Academy’s web site as is, proving the background in the videos was merely an ordinary background, not a green screen for CGI.
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The United Arab Emirates astronaut, Hazza Al Mansouri, took pictures of Earth’s features like the Nile and the Persian Gulf during his visit to the ISS. Flat-Earthers claim the pictures are fake because the various objects appear very large compared to the size of the Earth in the picture. The reason is that they do not understand that the ISS is only about 400 km above Earth’s surface, and only a very small amount of the Earth’s surface is visible from the ISS
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The International Space Station (ISS) is only about 400 km above the Earth’s surface, only 6% farther from the center of the Earth than the Earth’s surface. Therefore, only a very small part of Earth’s surface is visible from the ISS at any time.
Flat-Earthers like to examine photos of the Earth from the ISS and compare them to those taken from a much farther location. They would take any difference as an inconsistency. In reality, the ISS can only observe a very small part of the Earth, unlike spacecraft much farther away.
Continue reading “View of the Earth from the ISS”
Generally, sunlit objects are far brighter than any stars. It is the reason stars are not visible in a lot of photographs showing sunlit objects unless the objects are overexposed and made much brighter than the correct exposure.
Flat-Earthers take the lack of stars in photographs as evidence of misconduct. They are wrong. If the primary object in the picture is sunlit, then in most cases, stars will not be visible.
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Many adherents of flat Earth have spent a lot of effort and money to perform various observations and experiments. They would buy expensive equipment, travel to the other side of the world, painstakingly designed the experiments in minute details, and performed large-scale experiments; all to prove the notion that Earth is flat. However, many of these experiments and observations have actually confirmed the Earth is a sphere beyond any doubt.
In most cases, they would not accept such conclusions, and instead, they misinterpret, refuse to accept, lie, and withhold information. Such behaviors are the results of confirmation bias. However, their results speak louder than their biased conclusions, and these are perfectly valid proofs that Earth is a sphere.
These are some of those observations and experiments, where flat-Earthers have painstakingly and extravagantly performed them, only to come up with the wrong conclusions and spectacularly demonstrating their confirmation biases to the entire world.
Continue reading “Proofs of Spherical Earth Presented by Flat-Earthers”
Flat-Earthers reject the existence of satellites. They are wrong. To prove the existence satellites, we can attempt to take pictures of the ISS when an ISS transit happens, or the ISS passes in front of the Sun or the Moon.
Continue reading “Observing the ISS from ISS Transits”