interesting detritus

Today's interesting fact of the day:

In spanish, the word la mañana means both "tomorrow" and "morning". zibblsnrt informs me that the same is true in German. So this got me curious, and I wondered if the 'mor' part of both words suggests a similiarity in English that isn't obviously apperant, and so I checked etymology, and got this for "tomorrow":

[Middle English to morow, from Old English t morgenne, in the morning : t, at, on; see to + morgenne, dative of morgen, morning.]

Now, I'm trying to figure out how this nifty little tidbit happened. How did we come to associate 'tomorrow' so strongly with 'morning'?

[Edit #1: Huh, another linguistical oddity. jillcaligirl informs me that, in all the romance languages and Germanic, the words for 'three' and 'mother' are very similiar. I don't see that one as easily. Hmmm.]

[Edit #2: Oh. Jill informs me it's like this. All the words for 'three' are very similiar. All the words for 'mother' are similiar. zibblsnrt adds father to that list. I misunderstood my sister. Ah, fun with linguistics.]