The angle (or altitude) to Polaris approximately corresponds to the latitude of the observer. This fact is observed on every location on Earth where Polaris is visible.
By tracing the path to Polaris from multiple locations on the flat Earth model, the lines will not point to a consistent position of Polaris. The reason is that the Earth is a sphere and the flat Earth model does not represent reality.
Continue reading “Polaris Altitude from Multiple Locations on Earth”
Stars are not visible in photos of the Moon –including those taken from the lunar surface— because the Moon is sunlit. The exposure needed to take a photograph of the Moon is not that much different from that used to take a photo in daylight on Earth’s surface.
To demonstrate this, we can try taking a picture of the Moon with stars visible, on the conditions: 1. The lunar features, like the craters, are correctly exposed, not overexposed. 2. Taken in a single exposure, not HDR, and not the result of editing. Even if we are using the best camera available today, the stars can’t show up in large enough quantity.
Continue reading “The Moon and Stars in a Single Picture”
An analemma is a photograph or diagram showing the position of the Sun in the sky, as seen from a fixed location on Earth at the same mean solar time, as that position varies over the course of a year. The diagram will resemble the figure 8.
The north-south component of the 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.
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Visual albedo is the measure of the reflection of solar radiation out of the total solar radiation received by an astronomical body, taking into account only the visible light. The visual albedo of the Earth is 0.37, and the Moon’s is 0.12.
The Moon appears darker if the Earth also appears in the same photograph. Flat Earthers use the fact to “prove” that the picture is fake. They are wrong. The Moon appears darker because it reflects less sunlight than the Earth.
Continue reading “Visual Albedo of the Moon and the Earth”
The Giza-Orion correlation theory is a fringe hypothesis claiming the correlation between the design of the Giza pyramid complex and the position of Orion’s belt during the time the pyramids were built.
Some flat-Earthers use the Orion correlation theory to prove that stars never change. They are wrong. The theory already accounted for the shift in the position of the stars due to Earth’s axial precession. The theory was formulated using the position of Orion’s belt when Egyptians built the pyramids, not the current position of the stars.
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The apparent size of the Moon remains constant in a single day. This can only happen if the Moon is practically at the same distance all day.
In the flat-Earth model, the Moon is thought to be moving in a circle above the flat Earth. Such a notion should cause the Moon apparent size to vary in a day. However, in reality, the Moon appears in the same size all day, and it proves that the flat-Earth model does not represent reality and that the Moon is much farther.
Continue reading “The Apparent Size of the Moon”
Due to Earth’s axial precession, the positions of Earth’s celestial poles shift gradually in a cycle of approximately 26000 years. These days, Polaris is very close to the north celestial pole. However, 2000 years ago, Kochab is much closer to the celestial pole than Polaris. In the next 2000 years, Errai will replace Polaris as our pole star.
Flat-Earthers claim that the stars are always in the same position proves the Earth is stationary. They are wrong. By observing old star charts from a few centuries ago, the shift of celestial poles can be determined. It proves stars are not always in the same position as today, and that the Earth is rotating.
Continue reading “Old Star Charts and Earth’s Axial Precession”
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.
Continue reading “Sunlit Objects and Visibility of Stars”
We can determine if a star is visible from a specific location using the declination of the star and the latitude of the observer, subject to other conditions like observer’s topology, the magnitude of the star, weather conditions, etc. It is possible to do this because Earth is a rotating sphere.
If the Earth is flat, every star would have been visible all night from every location. We don’t see the same stars every night because some of them are below the horizon and obscured by the Earth.
Continue reading “Determining the Visibility of a Star From Its Declination and the Observer’s Latitude”
The Moon is tidally locked. Half of the Moon is always facing the Earth. However, due to libration, we can take a glimpse of areas of the moon that are not always visible.
Flat-Earthers invented many “scenarios” to “explain” how the so many lunar-related phenomena can happen on the flat Earth model. Some of these “explanations” include “transparent Moon”, “hemisphere-shaped Moon”, “flat circular Moon”, etc. Lunar libration rules out the majority, if not all, of these “explanations.”
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Some flat-Earthers like to observe celestial phenomena and the positions of celestial objects. Sometimes, they insist such events cannot possibly happen if the Earth is a sphere orbiting the Sun, and took the wrong conclusion that the Earth must be flat.
We can try asking them the time of the occurrence and the position of the observer, then use Stellarium or similar applications to simulate it. If the result matches the observation, then they have nothing to complain about. Their confusion was only the result of their ignorance.
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The Sun emits sunrays to every direction. But as the Sun is very far, the sun rays that reach us are practically parallel. To an observer on Earth, the rays of light coming from the Sun form a maximum angle of about 0.53°. They are practically parallel, but not perfectly parallel.
Flat-Earthers often question the fact we say sun rays are parallel, but in any diagram of an eclipse, they are drawn at an angle. They merely confuse practicality with perfection. Sunrays are practically parallel, but they are not perfectly parallel.
Continue reading “Sunrays are Practically Parallel, but not Perfectly Parallel”
In astronomy, a celestial coordinate system is a system for specifying positions of celestial objects like satellites, planets, stars, etc. The origin of the coordinate can be anywhere, including Earth. If the coordinate system is Earth-centered, we call it a geocentric coordinate system.
Flat-Earthers are often triggered by the term ‘geocentric’. They would search inside astronomy books and scientific journals to find the word ‘geocentric’. If they can find it, they would use the fact as ‘evidence’ of geocentrism, or that the Earth is the center of the universe, and the Sun is revolving around the Earth.
They are wrong. In many cases, the term ‘geocentric’ refers to the origin of a coordinate system. And it has nothing to do with whether the Sun revolves around the Earth or the other way around.
Continue reading “Geocentric Coordinate System Does not Imply Geocentrism”
A circumpolar star is a star, as viewed from a given latitude on Earth, that never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars stay up there in the sky, even during the day.
Flat-Earthers claim the Earth is stationary because the same stars are always visible in the sky. They are wrong. Only circumpolar stars are always in the sky. There are others that are not circumpolar. Some are only visible during certain times in a year.
Continue reading “Circumpolar and Non-Circumpolar Stars”
Astrolabe is an astronomical instrument for measuring the altitude of the sun or stars, and to determine the solution of various problems in astronomy, time, and navigation. Astrolabe was used from classical antiquity, about 2nd century BC, until the age of discovery where it was superseded by the more accurate sextant, star charts, and time-keeping devices.
Flat-Earthers claim that astrolabes can only work because the Earth is flat. They are wrong. Astrolabes were designed using the spherical Earth model. To use an astrolabe, a good understanding of the spherical Earth model is required.
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Some people are confused that a full moon is visible all night, and think if the full moon is the result of the opposition of the moon from the sun, then a full moon should be visible only at midnight.
Flat-Earthers who have such spatial visualization problem take a step further and use it as ‘evidence’ that the Earth is not a sphere. They are wrong. The full moon phenomenon can easily be explained in the spherical Earth model.
Continue reading “Geometry of a Full Moon”
During an equinox (March 20 and September 22-23), the Sun is directly above the equator. If we are on the equator, an upright stick will not have a shadow in the middle of the day.
On any other location, the angle between the stick and the direction of sunlight will be the same as the observer’s latitude.
This fact can only occur if the Earth is a sphere, and only if the Sun is very far relative to the size of the Earth.
Continue reading “The Angle of a Shadow During Equinox”
We can’t observe stars moving relative to each other, and the shape of constellations looks the same every night. The reason is not that stars are stationary, but their motions are very slow and cannot be observed over the timescale of human life.
Flat Earthers claim that the fact constellations don’t appear to change as proof the Earth is stationary. They are wrong. Stars have proper motion, but they can only be observed using precise instruments over a long time. Constellations do change, but the change is slow and cannot be perceived over the timescale of human life.
Continue reading “The Change of Constellations”
Polaris is a bright star that is close to the north celestial pole. Currently, Polaris is only 0.74° apart from the north celestial pole and the only star visible to the naked eye that is close to the celestial pole. This is why Polaris is popular as a navigational aid in the northern hemisphere.
Some flat-Earthers think that Polaris is stationary and that it is a ‘special star’ because other stars are in motion around it. They would take that as ‘evidence’ that the Earth is motionless. They are wrong. Polaris is merely a regular star, just like the others.
Continue reading “Polaris is not Stationary in the Sky”
Any diagram showing two or more celestial bodies is almost never drawn in the correct scale. The reason is that in most cases, any two celestial bodies are spaced too far away relative to their sizes. It is just not possible to draw them in the correct scale and still effectively describes what we want to explain. We don’t have much choice other than drawing them not to scale.
The perpetrators of flat-Earth disseminate the allegations that the diagrams were drawn not to scale because of evil intentions, and not because of legitimate technical reasons. Some people don’t understand this and fell victim to flat-Earth indoctrination.
Continue reading “Total Lunar Eclipse, Drawn to Scale”