Jupiter has four moons (Io, Europa, Ganymede, & Callisto) that we can easily observe using a binocular or telescope. They are the first objects found to orbit another, proving it is possible for a satellite to orbit planets other than Earth.
Flat-Earthers like to demand evidence of an object orbiting another. All they have to do is use a telescope to observe Jupiter. Its moons have short orbital periods (1.8 to 16.7 days), & thus, it is not hard to observe the orbiting motion.
Continue reading “Galilean Moons: First Objects Observed to Orbit Another Object”
Many Islamic rituals rely on the observations of astronomical events. Presently, many such observations are supplanted by calculations involving the knowledge that Earth is a sphere. These calculations give the same consistent results as direct observations on all locations on Earth for several centuries already. The fact confirms that Earth is indeed a sphere.
Some Muslims believe in flat Earth and then try to integrate the belief that Earth is flat into their religion. It results in an interesting phenomenon that they perform their religious rituals using the results of spherical Earth calculations but have severe difficulties accepting the fact. It can result in a spectacular cognitive dissonance after being made aware of it.
Continue reading “Islamic Rituals and Spherical Earth”
Turning Torso is a skyscraper in Malmö, Sweden, having a distinctive segmented shape & easy to recognize from far. From Copenhagen, Denmark, we can see its lower part is obscured more if we are farther because Earth is a sphere.
The building is close to the strait of Øresund. Copenhagen, Denmark, lies at the other side of the channel, only 15 km (9 miles) away from Malmö. Turning Torso has a distinctive segmented shape that is easy to recognize from far. And more importantly, for our purposes, its segmented form makes it easy to judge its height from far.
Continue reading “Turning Torso Building, Malmö, Sweden”
Using a drone, we can observe a sunset, then climb up and watch the same sunset again for the second time. The observation is only possible because Earth is a sphere.
Continue reading “Sunset and Drone”
Because Earth is a sphere moving around the Sun, we can easily see the Milky Way’s center only in certain months. In other months, the Milky Way will be too close to the Sun in the sky, where sunlight will overwhelm and obscure it from view.
Flat-Earthers claim that the Milky Way is visible every night “proves” a flat Earth. In reality, we are inside the Milky Way, and some parts will be visible. However, a specific part of it, like its brighter center, will not be visible every night.
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.
Continue reading “Satellite Watching”
Lasers are distinguished from other light sources by their coherence, or that their frequency and waveform are identical, and the output being a narrow beam. But lasers are still a form of light and exhibit the same characteristics as other light sources.
Flat-Earthers assume lasers always travel in a straight line, not affected by the medium. They use this incorrect assumption in their “experiments” to “prove” a flat Earth. In reality, like other light sources, atmospheric refraction can bend laser beams.
Continue reading “Refraction of Laser Beam”
Flat-Earth is a con initially designed to appeal to the potential victims in the Northern hemisphere. At a glance, some of the claims are seemingly in line with observation in the Northern hemisphere, but they are easily disproven when tested in the Southern hemisphere.
90% of all humans live in the Northern hemisphere. And it made sense of these con artists to invent the “facts” with the northern markets in mind while hoping nobody would bother going to the Southern hemisphere only to verify them. It was realistic in the 19th century, but today, everyone can verify the southern facts. There is no excuse for us to become flat-Earth victims, especially those already living in the Southern hemisphere.
Continue reading “Southern Hemisphere: Where Many Flat-Earth Claims are Disproven”
In graphical, linear perspective, the horizon is the horizontal line where the vanishing points for level objects lie. However, as the Earth is a sphere, the horizon of linear perspective is not the same as the true horizon, which is the line that we observe separating Earth from the sky.
Flat-Earthers claim that the observed horizon is produced by the law of perspective. In reality, from a high vantage point, we can try extending level and parallel lines to find their vanishing points. In many cases, they will end up above the true horizon.
Continue reading “True Horizon and Linear Perspective”
To an observer on the ground, an airplane at 36000 ft will start going over Earth’s curvature at a distance of 400 km. However, we are also limited by atmospheric visibility. In an extremely best-case scenario, we can only see up to 240 km.
We can easily see ships going over Earth’s curvature, and flat-Earthers like to demand us the same thing for airplanes. In reality, at the typical distance a plane does that, it is far out of visibility range. But if it is very low, like when approaching a runway to land, it is possible to see the plane going over the curvature of the Earth.
Continue reading “Airplanes Going Over Earth’s Curvature”
At the cruising altitude of a jet airliner, Earth’s curvature is too slight for us to notice casually. But with planning and careful observation, it is not impossible to see the curvature. Continue reading “Observing Earth’s Curvature From a Flight”
Using a precise digital kitchen scale and a smartphone with a pressure sensor, we can easily measure the change in weight and atmospheric pressure in different locations.
Flat-Earthers claim that an object falls down because it is denser than the air surrounding it. However, simple measurements show that things weigh less at a higher altitude where the air is less dense, contrary to the expectation if their claim is true.
Continue reading “Weight and Air Density Experiment”
A Sun outage is a disruption of geostationary satellite signal caused by interference of the sun when it falls directly behind a satellite with which a receiver is communicating. Sun outages occur around the March equinox and September equinox.
Flat-Earthers fail to understand how the schedule of a Sun outage depends on the satellite and the receiver’s location. And they use it to discredit the fact. In reality, it is not difficult to visualize how a Sun outage occurs, and it will be consistent with the expectation.
Continue reading “Sun Outage”
Because Earth is a sphere, the horizon always lies below eye level. We cannot see it near Earth’s surface with the naked eye. But with a precise instrument like a theodolite, we can observe the dip of the horizon.
Flat-Earthers claim that the horizon always rises to eye level. In reality, even from very close to Earth’s surface, it is still possible to observe that the horizon lies below eye level.
Continue reading “Theodolite and the Dip of the Horizon”
The “Flat Earth Dome Model” (walter.bislins.ch/FED) is an app created by a fellow flat Earth debunker, Walter Bislin. The app attempts to map observed reality to the flat Earth model. Lines in the app portray how light rays must have traveled if Earth were flat. They demonstrate that light must bend in a physically impossible way if Earth were flat, disproving a flat Earth.
Videos of the app are circulating in flat-Earth communities, and flat-Earthers fail to understand what the app is showing. They incorrectly assume the app “proves” a flat Earth when in reality, it thoroughly disproves the flat Earth model.
Continue reading “Flat Earth Dome Model”
The sky appears practically identical to all observers on Earth, except that the Earth obstructs the view to a different part of the sky to a different observer on Earth, and daylight obscures the view to most objects in the sky.
The fact that the sky appears identical everywhere on Earth can only be adequately explained if all the astronomical objects are very far from us and that the Earth is a sphere.
Continue reading “Sky”
At a lower altitude, the air is denser, and objects weigh more. On the other hand, at a higher altitude, the air is less dense, and objects weigh less.
Flat-Earthers deny gravity and invented the “explanation” that an object falls only because it is denser than the air surrounding it. But if it were true, objects should weigh more at a higher altitude where the air is less dense. But they weigh less instead, disproving flat-Earthers’ density theory.
Continue reading “Air Density vs Object’s Weight”
With careful planning, we can easily observe Earth’s curvature from an airliner. To “explain” the observation, flat-Earthers invented the excuse that it is caused by the distortion from the shape of the airplane’s window.
In reality, all camera lenses are curved, too, yet most of these lenses produce normal, rectilinear images. The fact that the shape of the window is curved does not mean looking through the window will produce a curved horizon.
Continue reading “Curved Airplane Window and Observation of Earth’s Curvature”
Flat-Earthers often show us images of a lamp illuminating a dark wall to demonstrate —incorrectly— how night can happen on a flat Earth.
In the images, the areas farther from the lamp appear dark. Due to the inverse-square law, areas farther than the source of light receive less light. However, these areas still receive light nonetheless. From these dark areas, the lamp is still visible. This contrasts with what happens at night, that sunlight is nonexistent and the sun is not visible.
Continue reading “Lamp Illuminating a Dark Wall Demonstration”
If we look toward the south at night in any location in the southern hemisphere, we will see the same set of stars. We will see the stars rotating around the south celestial pole, in the Octans constellation, near the star Sigma Octantis.
The flat-Earth model cannot explain the phenomenon. Looking at the so-called ‘flat-Earth map,’ we should see another set of stars on a different location in the southern hemisphere. The reason is that the flat-Earth model is a false representation of the Earth.
Continue reading “Stars in the Southern Sky Prove Earth is a Rotating Sphere”