>
> idea of a point of reference in astronomy is a necessarily trivial
> thing. When making a model of the universe we can say that the stars,
> the planets, and the earth all revolve around the sun, in a
> Heliocentric model. We could also convert this model to any other
> model with another point of reference, although it would be far more
> complex to say everything revolved around the earth. Is anyone
> familiar with the math involved in these calculations, and might point
> me to a book?
>
> I believe that there is other life out there, on other planets. My
> theory is that the sun is the only star, and the other stars are just
> bright and distant planets with life on them, the same as earth. I
> think life can burn up and turn to light, and when it travels off of
> one planet the photosenthetic life on another planet will catch it and
> trap it on the new planet. But this is crazy, yes? :)
>
>
http://en.wikipedia.org/wiki/Heliocentrism
>
> The realization that the heliocentric view was also not true in a
> strict sense was achieved in steps. That the Sun was not the center of
> the universe, but one of innumerable stars, was strongly advocated by
> the mystic Giordano Bruno; Galileo made the same point, but said very
> little on the matter, perhaps not wishing to incur the church's wrath.
> Over the course of the 18th and 19th centuries, the status of the Sun
> as merely one star among many became increasingly obvious. By the 20th
> century, even before the discovery that there are many galaxies, it
> was no longer an issue.
>
> Even if the discussion is limited to the solar system, the sun is not
> at the geometric center of any planet's orbit, but rather at one focus
> of the elliptical orbit. Furthermore, to the extent that a planet's
> mass cannot be neglected in comparison to the Sun's mass, the center
> of gravity of the solar system is displaced slightly away from the
> center of the Sun. (The masses of the planets, mostly Jupiter, amount
> to 0.14%% of that of the Sun.) Therefore a hypothetical astronomer on
> an extrasolar planet would observe a "wobble".
>
> Giving up the whole concept of being "at rest" is related to the
> principle of relativity. While, assuming an unbounded universe, it was
> clear there is no privileged position in space, until postulation of
> the special theory of relativity by Albert Einstein, at least the
> existence of a privileged class of inertial systems absolutely at rest
> was assumed, in particular in the form of the hypothesis of the
> luminiferous aether. Some forms of Mach's principle consider the frame
> at rest with respect to the masses in the universe to have special
> properties.
>
> Modern use of geocentric and heliocentric
>
> In modern calculations, the origin and orientation of a coordinate
> system often have to be selected. For practical reasons, systems with
> their origin in the mass, solar mass or in the center of mass of solar
> system are frequently selected. The adjectives may be used in this
> context. However, such selection of coordinates has no philosophical
> or physical implications.
>
> Fred Hoyle wrote:
>
> The relation of the two pictures [geocentricity and
> heliocentricity] is reduced to a mere coordinate transformation and it
> is the main tenet of the Einstein's theory that any two ways of
> looking at the world which are related to each other by a coordinate
> transformation are entirely equivalent from a physical point of view.
> (Hoyle, 1973, p. 78)