Flat-Earthers often make an unreasonable demand that astronauts in space zoom in using a camera toward the upside-down horizon to reveal an upside-down object on the horizon.
If we cannot zoom in toward the horizon from a flight to reveal objects on the horizon, then it is unrealistic to expect astronauts to be able to zoom in to reveal objects on the horizon.
Horizon’s distance from a flight is approximately 350 km. We cannot zoom in on an object that far away because it is beyond the visibility range and would require a huge camera lens to resolve it. And it will be much more unrealistic to do it from space.
NASA maintains a database of astronaut photography in eol.jsc.nasa.gov that we can search by many parameters, including focal length. By searching for focal length above 28mm, we can ensure the resulting images are not fisheye.
Flat-Earthers claim all NASA images are fisheye. In reality, most images in eol.jsc.nasa.gov are not fisheye. NASA also preserves the images’ EXIF data containing the camera & lens info. Sometimes even the raw images are available.
Continue reading “NASA’s Non-Fisheye Images”
A camera in automatic mode will evaluate the entire scene and choose the exposure automatically. If the entire scene appears too dark, the camera will increase the exposure. If the entire scene is too bright, it will decrease the exposure.
If the intended object is small, bright, and on a dark background like a sunset, changing zoom will affect the overall brightness of the entire scene. The automatic mode might choose an incorrect exposure. It is the source of much flat-Earth misinformation & can be corrected using manual exposure.
Continue reading “Changing Camera Zoom Changes the Exposure in Automatic Mode”
The Lake Pontchartrain causeway and transmission lines demonstrate Earth’s curvature. Flat-Earthers attempt to dismiss it using aerial photos where it is more difficult to see the curved landmarks over water.
On the other hand, from these alternative vantage points, it becomes easier to reveal the horizontal curvature by magnifying vertically. Because of the possibility of lens distortions, some of the images are inadequate evidence of the curve. However, all of them are insufficient evidence of a flat Earth.
During a total solar eclipse, the Moon’s side facing Earth does not receive sunlight but still receives light reflected from Earth’s surface. The phenomenon is called Earthshine and can be captured using a camera with a long exposure.
Flat-Earthers demand visual evidence of the Moon blocking the Sun during a solar eclipse. Earthshine provides this visual evidence & shows that the Moon is blocking the Sun.
Continue reading “Earthshine Shows the Moon Obscuring the Sun During a Total Solar Eclipse”
The Tiangong space station is equipped with a panoramic camera. It produces panoramic video in the equirectangular projection. It has a field of view of more than 180° & can see “behind” the camera. The image is unlike what our eyes see.
Flat-Earthers noticed the “funny” shape of the Earth from the Tiangong’s live stream & use it to discredit the mission. In reality, the image is panoramic. It shows the view behind the camera & cannot be compared to what our eyes would see.
Continue reading “Tiangong Space Station’s Panoramic Video”
An analemma is an image or diagram showing the change in the position of the Sun in the sky, seen from a fixed location on Earth, at the same time every day, over the course of a year.
The north-south component of an analemma results from the change in the Sun’s declination due to the tilt of Earth’s axis of rotation. The east-west component results from the non-uniform rate of change of the Sun’s right ascension, governed by the combined effects of Earth’s axial tilt and orbital eccentricity.
Continue reading “Analemma”
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.
Continue reading “Point Source”
The lunar surface is as dark as worn asphalt. It appears bright at night because everything else is darker. And in photos, its brightness is only a matter of the camera’s exposure settings.
In photos taken on the Moon, its surface looks dark unlike the Moon at night & flat-Earthers dismiss them as fake. In reality, it is just a matter of camera exposure. We can easily turn worn asphalt to look bright in photos by changing the exposure the same way the lunar surface can look bright or dark in photos.
Continue reading “Lunar Surface: As Dark As Worn Asphalt”
A satellite’s size is as small as a mobile phone to as large as a football field. The largest is 109 m, still far too small compared to Earth at 2742 km in diameter.
Satellites are not visible in Earth images. Flat-Earthers use the fact as “evidence” of deception. In reality, satellites are tiny compared to Earth. They are invisible in Earth images the same way ants are not visible in images of a football field.
Continue reading “Satellites in Earth’s Photos”
A photographic lens may have a specific distortion characteristic and strength that may differ from another lens. However, despite the differences, a straight line will always appear straight if it crosses the center of the frame.
Flat-Earthers like to dismiss images taken by a fisheye lens. In reality, the attributes of such a lens are well known. We can use the knowledge to determine if a line in the image is straight, even if it was taken using a fisheye lens.
Continue reading “Fisheye Lenses and Lens Distortions”
A camera with a zoom lens has a variable field of view but a fixed output resolution. As a result, its angular resolution depends on the zoom factor. Changing the zoom factor will change the ability of the camera to resolve a distant object.
Flat-Earthers show us zooming in reveals an unseen object & uses it to “disprove” Earth’s curve. In reality, the object was previously unseen due to the angular resolution limit at wide zoom. It is not far enough to be obscured by Earth’s curvature.
Continue reading “Zoom, Digital Resolution, and the Visibility of a Distant Object”
To monitor the ozone hole, NOAA launches a balloon every week on several locations on Earth. Scientists who launch the balloons like to create multiple exposure photos of the event. A single balloon appears multiple times in the resulting photos.
Flat-Earthers saw the “many balloons in a row” photos, & they incorrectly use them as the “explanation” of the appearance of the SpaceX Starlink satellites. In reality, the photos are just multiple exposure photos. There is only a single balloon, but taken multiple times and then merged into a single photo.
Continue reading “Multiple Exposure Photos of Balloons and SpaceX StarLink Satellites”
An ultra wide-angle lens produces images with an extremely wide angle of view. A lens with a focal length shorter than 24 mm (full-frame equivalent) is considered an ultra wide-angle lens. Ultra wide-angle lenses come in two varieties: rectilinear lens and curvilinear, or fisheye lens.
Because of their wide field of view, Earth’s curvature is easier to observe using an ultra-wide lens. Flat-Earthers incorrectly assumed it means a fisheye lens that distorts straight lines. In reality, there are rectilinear ultra wide-angle lenses that preserve straight lines. With these lenses, if the horizon looks curved, then it must be due to Earth’s curvature itself.
Continue reading “Ultra Wide-Angle Lens”
Camera zoom works by enlarging the center portion of the image, or in other words, by making its field-of-view narrower. Zooming in on the setting sun will not reveal more of the sun and will only enlarge the size of the sun in the resulting image.
Flat-Earthers claim that zooming in on a setting sun will reveal the full sun and somehow lift it out of the water. In reality, they used incorrect exposure settings, making the sun still above the horizon appear already half-obscured by Earth’s curvature.
Zooming on the setting sun will never reveal the sun already obstructed by Earth’s curvature.
Continue reading “Zooming-In on the Setting Sun”
Defishing is a process for removing barrel distortions from fisheye images, producing rectilinear images that preserve straight lines. A different fisheye lens produces a different amount of distortion & needs a different defishing strength.
Flat-Earthers like to apply a stronger defishing parameter than necessary with the goal not to remove the distortions but to make the horizon flat. As a result, they not only remove barrel distortion from the image but also introduce pincushion distortion that straightens the curved horizon.
The horizon in the end image might appear flat. However, it is due to the distortion these flat-Earthers deliberately introduced to the image, not because the horizon is flat.
Continue reading “Defishing Fisheye Images Excessively to Flatten the Curved Horizon”
In photography, bokeh is the way a lens renders out-of-focus points of light. The shape of bokeh depends on the shape of the lens’s aperture more than the out-of-focus objects themselves.
Flat-Earthers fail to take properly-focused photos of stars and planets because of their lack of photography skills and because their cameras are not suitable for the purpose. They are just getting bokeh, which tells us more about their equipment (and lack of knowledge) than the actual intended objects.
Continue reading “Bokeh”
The first image of Earth from space was taken by the V-2 No. 13 rocket in 1946 using the DeFry 35mm movie film camera and a 50mm lens attached to the rocket. The camera had a relatively narrow field of view. As a result, Earth’s curvature is only very slightly visible.
Flat-Earthers claim the flat appearance in the photo “proves” a flat Earth. In reality, 1. by careful examination, we can see the curve, 2. the camera has a narrow field of view, reducing the visible curvature, 3. the photo shown by flat-Earthers is usually a cropped version, further reducing the visible curve, and 4. the photo matches the expected curvature according to simulation.
Continue reading “First Image of Earth From Space Taken By a V-2 Rocket”
The magnitude of the curvature that appears in a photograph of Earth’s curvature depends on several factors:
- The observer’s altitude.
- The camera’s field of view or focal length.
- The distortion characteristics of the camera lens.
Flat-Earthers like to dismiss a photo of Earth’s curvature by comparing it to another photo showing a different amount of curvature. In reality, to compare the visible curvature, we need to ensure all the images were taken from the same altitude, same field of view, and account for the lens’ distortion.
Continue reading “Magnitude of Visible Earth’s Curvature in a Photograph”
Image noise is a random variation of brightness or color information produced by a photo film or digital sensor. Image noise is an undesirable by-product of photography and does not come from the actual objects in the picture.
Image noise can be in the salt-and-pepper type, forming bright dots in the dark parts of the image. When appearing in the dark part of the Moon, flat-Earthers incorrectly claim they are stars, “proving” that the Moon is transparent. In reality, these are just image noise, not part of the actual objects.
Continue reading “Image Noise and The “Transparent Moon” Misinformation”