A Beraita is cited in Berachot 30a as follows:
ת"ר סומא ומי שאינו יכול לכוין את הרוחות יכוין לבו כנגד אביו שבשמים שנא' והתפללו אל ה' היה עומד בח"ל יכוין את לבו כנגד ארץ ישראל שנא' והתפללו אליך דרך ארצם היה עומד בארץ ישראל יכוין את לבו כנגד ירושלים שנאמר והתפללו אל ה' דרך העיר אשר בחרת היה עומד בירושלים יכוין את לבו כנגד בית המקדש שנאמר והתפללו אל הבית הזה היה עומד בבית המקדש יכוין את לבו כנגד בית קדשי הקדשים שנאמר והתפללו אל המקום הזה היה עומד בבית קדשי הקדשים יכוין את לבו כנגד בית הכפורת היה עומד אחורי בית הכפורת יראה עצמו כאילו לפני הכפורת נמצא עומד במזרח מחזיר פניו למערב במערב מחזיר פניו למזרח בדרום מחזיר פניו לצפון בצפון מחזיר פניו לדרום נמצאו כל ישראל מכוונין את לבם למקום אחד א"ר אבין ואיתימא ר' אבינא מאי קראה כמגדל דויד צוארך בנוי לתלפיות תל שכל פיות פונים בו
Our Rabbis taught: A blind man or one who cannot tell the cardinal points should direct his heart towards his Father in Heaven, as it says, And they pray unto the Lord. If one is standing outside Palestine, he should turn mentally towards Eretz Israel, as it says, And pray unto Thee towards their land. If he stands in Eretz Israel he should turn mentally towards Jerusalem, as it says, And they pray unto the Lord toward the city which Thou hast chosen. If he is standing in Jerusalem he should turn mentally towards the Sanctuary, as it says, If they pray toward this house. If he is standing in the Sanctuary, he should turn mentally towards the Holy of Holies, as it says, If they pray toward this place. If he was standing in the Holy of Holies he should turn mentally towards the mercy-seat. If he was standing behind the mercy-seat he should imagine himself to be in front of the mercy-seat. Consequently, if he is in the east he should turn his face to the west; if in the west he should turn his face to the east; if in the south he should turn his face to the north; if in the north he should turn his face to the south. In this way all Israel will be turning their hearts towards one place. R. Abin — or as some say R. Abina — said: What text confirms this? — Thy neck is like the tower of David builded with turrets [talpioth], the elevation [tel] towards which all mouths (piyyoth) turn.
Given a spherical Earth, if I am situated to the west of Israel I will be facing Israel whether I face east or west, as you can see below:
This leaves me with several options:
The author of this Beraita was not aware that the Earth was spherical, and therefore assumed that in order to face Israel from any given point in the world, there was only one specific direction that you could face.
The author of the Beraita was aware that the Earth is spherical, and the point being conveyed is that (even though you can be facing Israel even if you face a different way) you have to face Israel in the most direct way, i.e. whichever way is closer.
The Beraita is not fully precise, and indeed the terms "east" and "west" (and "north" and "south") don't mean much when the Earth is spherical, and you can in fact face Israel in whichever way you want as long as you are actually facing it.
The differences in these options can result in different halachic conclusions. The second option in particular, if taken to the extreme, would mean that someone would have to determine the precise point in the Pacific Ocean where the shorter direction changes.
This Beraita is codified by all the major codes, yet I did not find any of them, or the standard commentaries thereon, discuss this aspect. Rambam's formulation in Hilchot Tefilah 5:3 may avoid the whole issue, as he leaves out the end of the Beraita which discusses the actual directions:
נכח המקדש כיצד היה עומד בחוצה לארץ מחזיר פניו נכח ארץ ישראל ומתפלל היה עומד בארץ מכוין את פניו כנגד ירושלים היה עומד בירושלים מכוין פניו כנגד המקדש היה עומד במקדש מכוין פניו כנגד בית קדש הקדשים סומא ומי שלא יכול לכוין את הרוחות והמהלך בספינה יכוין את לבו כנגד השכינה ויתפלל
Facing the Temple: What is implied?
A person standing in the Diaspora should face Eretz Yisrael and pray.
One standing in Eretz Yisrael should face Jerusalem.
One standing in Jerusalem should face the Temple.
One standing in the Temple should face the Holy of Holies.
A blind person, one who is unable to determine direction, or one travelling in a boat should direct his heart towards the Divine Presence and pray.
This could be taken to mean that you can face any direction as long as it is towards Israel, since he doesn't mention any specific direction that must be faced.
So, to conclude, which (if any) of my three options above are correct?
Is this issue addressed in Rabbinic Literature?
Are any of my geographical assumptions incorrect?