Transmutation Circles

[drgenestarwind]

It's explained quite well that all alchemic reactions require transmutation circles, whether they be drawn from in the dirt, on clothing/skin, blood, or chalk, and in the case of Izumi and Edward, connecting their arms to form a circle is good enough. and manga spoiler...
trying to turn Amestris itself into a transmutation circle with the tunnel would even seem to work
we see various alchemists making up their own circles for their own purposes, in lab 5 Ed makes a seven point circle, the symbol on Al's arm and Ed's Jacket is for human transmutations. it's never explained why different circles are needed, it's just assumed that each alchemist does their best with their own knowledge.
refering back to the manga spoiler what if the whole earth were made into a transmutation circle, would the change from euclidian geometry to spherical geometry have a profound impact on the capabilities of alchemy. is something that size prohibitive or ultra powerful?

[mooseegg1982]

Spoilers:
I thought that the symbol on Ed's jacket was part of a transmutation circle that could destroy homonculi. Atleast in the anime.

[Tom Servo]

what if the whole earth were made into a transmutation circle, would the change from euclidian geometry to spherical geometry have a profound impact on the capabilities of alchemy. is something that size prohibitive or ultra powerful?
Haven't seen or read F.M.A. so I dunno how the mechanics of circles work in the show.

The Earth is surrounded by a circle of stars whose Greek name is zodiac, this is part of the sphere of stars whose Greek name is stathera asteria. A circle drawn around an operator along with other paraphernalia seeks to create the same conditions that surround the Earth.

In other words the Earth is already surrounded by a circle, you're coming at it backwards.