Astronomy/Fool Proof



I think I saw two different models for a Geocentric universe.  Then there's the heliocentric.

Isn't there a "fool proof" "absolute way" to determine which is correct via the different orbital VIEWS from earth ? ?



I am assuming in this question that what you really mean is "different models for the solar system".  (Since the universe, by virtue of the simultaneous expansion of space AND time has no definable center, i.e. which can be "viewed" or distinguished.)

IN *this* context there is a foolproof way, and it's called celestial mechanics. This is the science that enables us to correctly identify the future positions of planets from earlier ones, e.g. using equations such as:

w  = M + (2e – e^3 / 4) sin M + 5 e^2/4 sin 2M + ....

where M is the mean anomaly and w is the argument of the perihelion

It doesn't matter if you know what these terms mean or not. The point is that celestial mechanics enables us to not only correctly predict the future positions of planets, but also to correct compute the trajectory of spacecraft to those planets.

Geocentric astronomy doesn't since it must be jury rigged (using Prolemy's epicycles for example_ to try to get the correct results and even then they're not correct.

Thus it is that the over-complicated system of epicycles is rendered redundant once one understands and appreciates the planets move in elliptical orbits, not in circular ones. Ptolemy’s error was in trying to squeeze planetary motions into a “perfect” circular mold. Once this change to the actual physical orbits was made, then the appropriate equations, such as Kepler’s, e.g.

n(t – T) = E – e sin E

where n is the mean motion (in degrees per day or per second), t the referenced time, T the time of perihelion passage (e.g. closest point to the Sun), e is the eccentricity and E is the eccentric anomaly.

This can then be used in conjunction with others to arrive at the orbital elements for all the planets. These include: the eccentricity of the orbit, e (e.g. how elliptical it is or the deviation from circularity), the semi-major axis, a, or the mean distance to the Sun, the inclination (i) of the orbit – or the tilt of its plane with respect to the reference plane, and others.

As for using  "different views from Earth" this will almost always be tricky because all parties would first need to agree on the same instruments, and methods to make such observations.

Second, it is likely much subjectivity would enter. For example, how would one "absolutely" determine that Mr. A's measurement of a planet's velocity at aphelion (as well as the perihelion velocity) is the same as Mr B's

These differences would be critical in showing the angular momentum (L = mvR)  at those orbital points are different, and hence imply elliptical orbits - which means geocentric views are inapplicable for the reasons stated. However, if Mr. B's methods and instruments yield little or no difference he could well argue that the orbit is circular and hence no specialized treatments are needed. So a geocentric view might then be accepted.

In the end, the very fact celestial mechanics works, i.e. in getting spacecraft to land on Mars or the Moon, ought to provide all the absolute means, by which I mean "fool proof", one needs

Hope this helps.  


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Philip Stahl


I have more than forty years of experience in Astronomy, specifically solar and space physics. My specialties include the physics of solar flares, sunspots, including their effects on Earth and statistics pertaining to sunspot morphology and flare geo-effectiveness.


Astronomy: Worked at university observatory in college, doing astrographic measurements. Developed first ever astronomy curriculum for secondary schools in Caribbean. Gave workshops in astrophysics and astronomical measurements at Harry Bayley Observatory, Barbados. M.Phil. degree in Physics/Solar Physics and more than twenty years as researcher with discovery of SID flares. Developed of first ever consistent magnetic arcade model for solar flares incorporating energy dissipation and accumulation. Develop first ever loop solar flare model using double layers and incorporating cavity resonators.

American Astronomical Society (Solar Physics and Dynamical Astronomy divisions), American Mathematical Society, American Geophysical Union.

Solar Physics (journal), The Journal of the Royal Astronomical Society of Canada, The Proceedings of the Meudon Solar Flare Workshop (1986), The Proceedings of the Caribbean Physics Conference (1985). Books: 'Selected Analyses in Solar Flare Plasma Dynamics', 'Physics Notes for Advanced Level'. 'Astronomy and Astrophysics: Notes, Problems and Solutions'.

B.A. Astronomy, M. Phil. Physics

Awards and Honors
American Astronomical Society Studentship Award (1984), Barbados Government Award for Solar Research (1980), Barbados Astronomical Society Award for Service as Journal Editor (1977-91)

Past/Present Clients
Caribbean Examinations Council, Barbados Astronomical Society, Trinidad & Tobago Astronomical Society.

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