I am not seen before the starlight,
yet, next to the moon, I stand.
Wait next to the power I might,
And here I am the last at hand,
Once, in mid-air you did find me,
between the ninth and thirteenth, see?
And soon you find me just behind me,
right after this, I sure will be.

Kenny has it right.  The solution is "a comma":

     I am not seen before the starlight [,]
(the comma appears after "starlight")
     yet, next to the moon[,] I stand.
(the comma stands next to "moon")
     Wait next to the power I might[,]
(the comma waits next to "might", a synonym for "power")
     And here I[']m the last at hand[,]
(the comma is the last character of this line, after "hand")
     Once, in mid-air you did find me,
(the comma in mid-air is the apostrophe in "I'm"...) 
     between the ninth and thirteenth, see?
(... between the 9^th letter, I, and 13^th letter, M, of the alphabet.
I have assumed that "I am" was once "I'm", but was probably
edited before this riddle was posted)
     And soon you find me just behind me,
(the comma follows behind the word "me")
     right after this, I sure will be.
(the comma follows right after the word "this")

Posted by Mindrod on 2006-02-19 18:48:23