Flat-Earthers often claim that “the horizon always rises to eye-level”, and thus ‘proving’ the flat Earth claim. Despite their insistence to use a water level to ‘prove’ water is flat, the same device can be used to demonstrate the dip of the horizon, proving the water surface has curvature, and consistent with the spherical Earth model.
A water level exploits the fact that water always finds its level. Looking at the surface of water formed in two vessels, we can aim at the horizon and determine the projected eye-level. If we are at a sufficient altitude, we should be able to observe that the horizon —the line separating the sky and the ground— lies below the eye-level.
As we climb higher, the larger is the dip. Conversely, as we approach sea level, the dip approaches zero.
Flat-Earthers often use water level as ‘proof’ that the surface of the water is flat. They are wrong. The surface of the water is level, or equipotential, but not perfectly flat.
A water level exploits the fact that water always finds its level. Looking at the surface of water formed in two vessels, we can aim at the horizon and determine the projected eye-level. If we are at a sufficient altitude, we should be able to observe that the horizon —the line separating the sky and the ground— lies below the eye-level.
As we climb higher, the larger is the dip. Conversely, as we approach sea level, the dip approaches zero.
Flat-Earthers often use water level as ‘proof’ that the surface of the water is flat. They are wrong. The surface of the water is level, or equipotential, but not perfectly flat.
Cellular phones do not function in a remote location, and flat-Earthers use the fact as “proof” that satellites do not exist. In reality, nobody claimed that cellular phones communicate with satellites. The phones that communicate with satellites are called satellite phones, and they still function in a remote location.
The major satellite phone providers in operation today are Inmarsat, Thuraya, and Iridium.
The major satellite phone providers in operation today are Inmarsat, Thuraya, and Iridium.
Various pictures showing satellites and space debris around the Earth are visualizations. They are not real photos taken from cameras. These visualizations were created by drawing the objects with sizes far larger than their actual dimensions. If they were drawn to scale, then they all will be too small and cannot be seen in the visualizations.
Flat-Earthers fail to realize that these are visualizations. They think the pictures are presented as real photos. Because we never see satellites like that, they concluded that it was a deception. In reality, these pictures are simply visualization, not actual photos.
Flat-Earthers fail to realize that these are visualizations. They think the pictures are presented as real photos. Because we never see satellites like that, they concluded that it was a deception. In reality, these pictures are simply visualization, not actual photos.
In these measurements, we measured a 1000 gram calibration weight using a digital coffee scale. The first measurement was done in Jakarta, Indonesia, at about 80 m above sea level. Because the calibration was also done with the same calibration weight at the exact location, then the scale also indicated 1000 grams. As for the air pressure, the phone stated 1002.2 hPa.
Then we traveled to Bandung, Indonesia, at about 750 m above sea level. Measurements gave us 999.72 grams and 929.3 hPa. The scale measured that the weight was slightly less, and the air was also less dense.
We repeated the first experiment to ensure that the measurement was not affected by the previous measurement or anything that occurred afterward (carry-over effect). It gave us the same number, 1000 grams. And the air pressure changed slightly to 1003.5 hPa.
Then we traveled to Bandung, Indonesia, at about 750 m above sea level. Measurements gave us 999.72 grams and 929.3 hPa. The scale measured that the weight was slightly less, and the air was also less dense.
We repeated the first experiment to ensure that the measurement was not affected by the previous measurement or anything that occurred afterward (carry-over effect). It gave us the same number, 1000 grams. And the air pressure changed slightly to 1003.5 hPa.
The largest satellite is the ISS, about 109 m in length. The Earth is 12742 km across and 116900× the size of the largest satellite. For comparison, if a football field is 110 m long and the size of an ant is 3 mm, then a football field is 36667× the size of an ant.
If the ant is not visible in a photo of an entire football field, then a satellite in an image of Earth is even less visible.
If the ant is not visible in a photo of an entire football field, then a satellite in an image of Earth is even less visible.
https://www.youtube.com/watch?v=sPQ-tMoAHkY&ab_channel=NASAWallops
Why satellites aren't the same as balloons.
Why satellites aren't the same as balloons.
YouTube
B-Line to Space: The Scientific Balloon Story
B-Line to Space: The Scientific Balloon Story is about NASA’s scientific balloons, which offer low-cost, near-space access for suspended payloads weighing up to 8,000 pounds. These balloons are used to conduct technology demonstration tests as well as scientific…
A different camera lens can produce a different shape of bokeh. Concentric circles (onion rings, shooting targets) usually result from aspherical lens elements. Polygonal shapes are due to the outlines of the lens’s aperture when stopped down. Donut-shaped bokeh is due to the obstruction by the secondary mirror in a mirror lens. The cat’s eye bokeh is caused by the cylindrical shape of the lens when the object is near the edge of the frame. The bokeh shape tells us more about the camera and lens than the intended objects.
Flat-Earthers invented wild assumptions to explain why stars and planets do not appear as they are supposed. The real explanation is more straightforward: these shapes are just bokeh, and they tell us more about their photography skills or the lack thereof.
Flat-Earthers invented wild assumptions to explain why stars and planets do not appear as they are supposed. The real explanation is more straightforward: these shapes are just bokeh, and they tell us more about their photography skills or the lack thereof.
A light bulb is a vacuum inside, with a glass wall separating the inner vacuum and the air outside. Air cannot travel toward the lower pressure area inside the bulb because the glass wall exerts the normal force —or the Van der Waals force— to the air outside.
A pressure tank is a container designed to hold fluids at a higher pressure from the ambient pressure. It does that by having a barrier preventing the fluids inside from going out. However, when the tank is being filled in, there is a connection from the outside to the inside, and it is not entirely sealed. The air outside can move toward the higher pressure area inside the tank —the reverse from the usual situation— because a pump is exerting a force to the air particles.
Without a force affecting air particles, the air would move to a lower pressure area, like a vacuum. A barrier can provide the normal force that can prevent air from moving to a smaller pressure area. However, it does not have to be a normal force. Other forces can affect air particles, too, including gravity.
A pressure tank is a container designed to hold fluids at a higher pressure from the ambient pressure. It does that by having a barrier preventing the fluids inside from going out. However, when the tank is being filled in, there is a connection from the outside to the inside, and it is not entirely sealed. The air outside can move toward the higher pressure area inside the tank —the reverse from the usual situation— because a pump is exerting a force to the air particles.
Without a force affecting air particles, the air would move to a lower pressure area, like a vacuum. A barrier can provide the normal force that can prevent air from moving to a smaller pressure area. However, it does not have to be a normal force. Other forces can affect air particles, too, including gravity.
Sun glare is caused by the scattering of sunlight in the atmosphere. And internal reflections in the optical system can also cause it.
The intensity of sun glare is less than the strength of the light coming directly from the Sun, but it is still too bright for our eyes to distinguish it from the sun itself. It is the reason the Sun and its glare appear as a single bright object.
To observe the Sun without its glare, we have to reduce the exposure by using the in-camera exposure settings or using a solar filter. By eliminating the glare, we can observe that the sun’s size remains constant throughout the day.
The intensity of sun glare is less than the strength of the light coming directly from the Sun, but it is still too bright for our eyes to distinguish it from the sun itself. It is the reason the Sun and its glare appear as a single bright object.
To observe the Sun without its glare, we have to reduce the exposure by using the in-camera exposure settings or using a solar filter. By eliminating the glare, we can observe that the sun’s size remains constant throughout the day.
All magnets have two poles. Breaking a bar magnet in the center will result in two bar magnets with two poles each. A compass needle also has two poles. Its north pole is attracted to the south pole of Earth’s magnetic field and vice versa.
Important: A magnet’s North pole is defined as the pole that is attracted by the Earth’s North Magnetic Pole when the magnet is suspended so it can turn freely. Since opposite poles attract, the North Magnetic Pole of the Earth is really the south pole of its magnetic field.
In addition to the force of attraction, there is also the force of repulsion. The north pole of a compass is repulsed by the north pole of Earth’s magnetic field and vice versa. Near the equator, all the forces have the same magnitude, and a compass will be level.
Flat-Earthers claim that only on a flat Earth, a compass needle will point to the North Pole. They ‘forgot’ to account for the fact that the south pole of the magnet is also affected by Earth’s magnetic field in the same way, making the compass level near the equator.
Additionally, at a location far enough from the equator, the phenomenon of magnetic dip will be more pronounced. A compass will need to be specifically designed to be used in such locations. Otherwise, the needle will bind and will not give us the correct results. This phenomenon is obviously not compatible with what is claimed by flat-Earthers: a balanced compass does not point to the north pole. The same excuse they are using to ‘disprove’ spherical Earth also applies to them.
Important: A magnet’s North pole is defined as the pole that is attracted by the Earth’s North Magnetic Pole when the magnet is suspended so it can turn freely. Since opposite poles attract, the North Magnetic Pole of the Earth is really the south pole of its magnetic field.
In addition to the force of attraction, there is also the force of repulsion. The north pole of a compass is repulsed by the north pole of Earth’s magnetic field and vice versa. Near the equator, all the forces have the same magnitude, and a compass will be level.
Flat-Earthers claim that only on a flat Earth, a compass needle will point to the North Pole. They ‘forgot’ to account for the fact that the south pole of the magnet is also affected by Earth’s magnetic field in the same way, making the compass level near the equator.
Additionally, at a location far enough from the equator, the phenomenon of magnetic dip will be more pronounced. A compass will need to be specifically designed to be used in such locations. Otherwise, the needle will bind and will not give us the correct results. This phenomenon is obviously not compatible with what is claimed by flat-Earthers: a balanced compass does not point to the north pole. The same excuse they are using to ‘disprove’ spherical Earth also applies to them.
I've asked this question before however I'll ask it again to separate the flerfs from the people grounded in reality.
Do you measure things that rotate/spin in mph or rpm?
Do you measure things that rotate/spin in mph or rpm?
Anonymous Quiz
14%
Mph
86%
Rpm
The camera used to take the photo was a 35mm movie film camera. It has a crop factor of approximately 1.5x. As a result, the attached 50mm camera would have an effective field of view equivalent to a ~75mm lens attached to a 35mm still camera. We can use this figure and the rocket’s altitude to determine the expected curvature from a simulation. And the result perfectly matches the photo.