Lyric discussion by FightingLee 

Cover art for One Tree Hill lyrics by U2

I'll see you again when the stars fall from the sky And the moon has turned red over One Tree Hill

this has strong reference to Revelations concerning the end of the 6000 year period and the second coming of Christ. At the time of his return it is said that the stars will fall from the sky and the moon turn red . . . events such as these will rush in the millenium or last thousand year reign of christ. At this time the first resurection will occur wear all those that have been deemed righteous will rise. This is in revelations and in ezekial of the old testemant. Anywho . . .

It sounds as if Bono is saying that he will see his friend again at the time that christ reigns and the dead are resurected. Clearly he says it so much more poetic though . . .