Celestial Sphere

Borrowed from antiquity, a cornerstone to astronomy is the Celestial Sphere, which describes that the celestial bodies are projected to a sphere or dome around the observer. Astronomers use a spherical coordinate system to describe the sky. A spherical celestial sky is often put forward as evidence for a spherical world.

Reading closer, the celestial sphere goes much further than it being a mere representation of a universe spread out around us. While some astronomers treat the celestial sphere as ficticious, other astronomers explain that straight lines in space will appear to us as curves on the celestial sphere. The Moon Tilt Illusion, in which the illuminated portion of the Moon often and paradoxically points upwards and away from the Sun, is attributed as an effect caused by the Sun and Moon resting at different angles upon the celestial sphere. The Milky Way, usually thought of as a flat entity viewed from the side, appears as a bending arch in the sky on the celestial sphere. The Sun's path bends and warps on the celestial sphere. So too do shooting stars, meteors, and the aurora curve upon the celestial sphere above us. We are told, essentially, that we observe the heavens as if we were inside of a planetarium, where straight lines become curved on a spherical surface around us.

Why should it be that a straight line in space is warped and curved? If a straight line was receding in distance from our position, at which point would that straight line become curved? The celestial sphere is proposed by conventional astronomy without a mechanism, and with only vague statements that it is natural to observe nature in this way. Actively ignored as a topic of discussion, neglected in astronomy texts, and mainly trotted out when forced to explain phenomena, the warping of lines upon the celestial sphere showcases the weakness and untenability of conventional astronomy.

In contrast to this, the Flat Earth Theory's celestial model directly provides a mechanism for why lines, containing points at different distances from the observer, appear curved in the sky and for our domed observations.

General Astronomy
The book General Astronomy (Archive) from WikiBooks says:

University of Virginia
An astronomy course at the University of Virginia describes (Archive):

New Jersey Institute of Technology
The New Jersey Institute of Technology states (Archive):

Princeton University
Professor of Astronomy Charles A.Young, Ph.D, defines spherical astronomy as (Archive):

“ Spherical Astronomy — This, discarding all consideration of absolute dimensions and distances, treats the heavenly bodies simply as objects moving on the “surface of the celestial sphere”: it has to do only with angles and directions, and, strictly regarded, is in fact merely Spherical Trigonometry applied to Astronomy. ”

On the Evolution of the Heavenly Spheres
A doctoral thesis explains that the the transformation of straight lines into curves on the celestial sphere has been known since antiquity.

On the Evolution of the Heavenly Spheres An Enactive Approach to Cosmography by David McConville

Full Text Link (Archive)

p.40



Footnotes:


 * 15 Kim Veltman (2004, p. 15) reviews the debate concerning the degree to which Euclid’s Optics was a precursor to either linear or spherical perspective in Literature on Perspective: Sources and Literature of Perspective.


 * 16 Kepler writes, "But our vision has no surface like that of a painting on which it may look at the picture of the hemisphere but only that surface of the sky above in which it sees comets, and it imagines a sphere by the natural instinct of vision. But if a picture of things is extended in straight lines into a concave sphere, and if our vision is in the center of this, the traces of those things will not be straight lines, but, by Hercules, curved ones" (Galilei, Drake, & O’Malley, 1960, pp. 354–355)


 * 17 James Elkins (1988, 1994) summarizes the dispute surrounding da Vinci’s position on the curvature of vision in “Did Leonardo develop a theory of curvilinear perspective?” and The Poetics of Perspective.


 * 18 Hershel (1869) writes, "In celestial perspective, every point to which the view is for the moment directed, is equally entitled to be considered as the "centre of the picture," every portion of the surface of the sphere being similarly related to the eye. Moreover, every straight line (supposed to be indefinitely prolonged) is projected into a semicircle of the sphere, that, namely, in which a plane passing through the line and the eye cuts its surface. And every system of parallel straight lines, in whatever direction, is projected into a system of semicircles of the sphere, meeting in two common apexes, or vanishing points, diametrically opposite to each other, one of which corresponds to the vanishing point of parallels in ordinary perspective; the other, in such perspective has no existence” (p.70)

Sun Path Warped
According to the conventional model the sun's path is a plane which intersects the observer's sky.

A Weber State University astronomy course by Dr. Daniel V. Schroeder (bio) shows the Sun's path is warped upon the celestial dome:

https://physics.weber.edu/schroeder/ua/sunandseasons.html (Archive)



Caption:

The above website explains the distortion as caused by 'stretching the domed sky onto a flat semicircle' -- as if there is a domed sky around us which modifies the position of the Sun. The diagram comes from the linked Sky Motion Applet.

Dr. Schroeder also provides the following multiple-exposure photo:



Moon and Venus Star Trails
Like the Sun on the celestial dome, Venus and the Moon can also be seen to follow the path of the stars.



"Crescent Moon Venus and star trails at Nagano, Norikura mountain" (Source)

Milky Way Arch
As with the ecliptic of the Sun, the Milky Way is thought to be a straight line entity which we are viewing from the side. Yet it has been asserted that the Milky Way is sometimes seen to be creating an arch in the sky.

Source: Matt Rohlader Photography | Caption: "The arch of the Milky Way as seen from Split Rock Lighthouse State Park near Two Harbors, MN."

A Google Image Search for 'Milky Way Arch' will provide many images of the Milky Way arching in the sky.

Photographs of the Milky Way Arch from Google Image Search have been described as being affected by wide-angle, fish-eye, composite, or other effects. While true that many images of the Milky Way Arch are affected by such distortion, sources tell us that the arch can be seen with the naked eye as well. Astronomer and Associate Editor Alison Klesman, Ph.D. (bio), at Astronomy Magazine informs us that sometimes cameras can produce distortion, and ends with the statement that the arc can also be seen with the naked eye. It is said that both the Milky Way and the ecliptic (the planar path of the Sun) project as a great circle onto the celestial sphere, which create straight lines overhead, and at lower altitudes create arcs in the sky:

http://www.astronomy.com/magazine/ask-astro/2018/09/seeing-a-curved-milky-way (Archive)

Comets
On p.359 of Elementary astronomy; a beginner's text-book (Archive) by Edward S. Holden, former director of Lick Observatory, it says:

Meteors
The International Meteor Organization (Archive) says:

http://www.internetsv.info/MeteorRC.html (Archive)

Aurora
Astronomer and mathematician Simon Newcomb (bio) tells us in his book Popular Astronomy that the aurora, too, projects upon the celestial sphere (Archive):

p.309

The Chautauquan
Another reference from The Chautauquan:

Moon Tilt Illusion
If the Moon is illuminated by the Sun then it is expected that the illuminated portion of the Moon will point at it. The Moon Tilt Illusion is a geometric anomaly in which the Moon is often seen to point upwards and away from the Sun. Astronomers attribute this to the Sun and Moon resting at different angles on the 'celestial sphere'.

Professor Alan Myers at the University of Pennsylvania says the following (Archive):

A diagram is provided:



Professor Myers informs us on the interest of astronomers in discussing this topic:

MetaBunk
A physics educator under the alias Henk001 was kind enough to take the time to provide us with a free science lecture on the workings of astronomy, instructing us with the following(Archive):

The educator explains that a 'celestial sphere' modifies the directions of the sun and moon, causing the illuminated portion of to Moon to point in a different direction. Following this enlightenment, our expert continues:

We are told by a molder of young minds that when something does not make sense about the world our intuition and correct course of action should be to surrender curiosity, criticism, and all sense of geometry. Instead, we must seek to "ask an expert"—stoic educators and pillars of the community who will proceed to correct our misunderstanding of nature with impeachable facts from science scholarship, such as with teachings of the celestial dome which the celestial bodies project upon at different angles and where straight lines become curved.

See the Moon Tilt Illusion

Sky Dome and Projections
Over the course of the year the path of the Sun is seen to curve upon a dome, which can be seen in sun charts. Penn State University provides an overview of 'sky domes', projections, and polar sun charts:

https://www.e-education.psu.edu/eme810/node/534 (Archive)

2.13 Sky Dome and Projections Sun Charts: Projections of Solar Events and Shadowing from the Sky Dome

The above is a polar sun chart, showing how the sun would move as if we were laying on the ground with our head towards the south. If one were to hold a large piece of paper straight up into the air, over the course of the year the sun would shine through the paper and trace arcs across the sky. Despite the sun's ecliptic being a plane which cuts through the earth, the path of the sun is seen to curve in the sky.

At the bottom of the page we see that the polar projection sun chart was generated with the University of Oregon's Polar Sun Chart Program. Using this tool to create a polar sun chart for the opposite Southern Hemisphere version of the above polar sun chart, for Latitude -40.79, we see the following:



Notice that the day of December 21st is convex in the Northern Hemisphere and concave in the Southern Hemisphere. The shape of the curve for the same day is seen to be convex or concave for different observers simultaneously, truly as if each observer had his or her own personal planitarium-like "dome" of vision.

Addendum
The effect of the 'celestial sphere' is seen to be quite literal. Distant observations paradoxically appear to project upon a sphere or dome around the observer. Usually discussed briefly and given as an explanation by astronomers without any apparent mechanism, the phenomena of lines projecting as curves on a celestial sphere is quite suggestive and of great interest to the Flat Earth investigation. In order for different observers to have his or her own personal dome where lines appear either concave or convex depending on position, the mechanism cannot be anything other than the curvature of light rays which create the appearance of our domed surroundings, and hence a piece of evidence for the Flat Earth's celestial model of Electromagnetic Acceleration.