Psalm 90 begins (ESV):
A prayer of Moses, the man of God.
Translations seem mostly to agree about this, although I’m not sure if that’s the only way to translate it.* This has traditionally been understood to reflect Mosaic authorship. From this article at bible.org by Bob Deffinbaugh:
Those who believe in Moses’ authorship of the psalm almost universally agree that Moses wrote this during the 40 years of Israel’s wilderness wanderings.
He disagrees with this view:
I believe Moses wrote it during his 40 years exile from Egypt while tending the flocks of his father-in-law.
He acknowledges, however, that many scholars believe it to have been written much later, by someone other than Moses.
What evidence is available to help us decide whether this psalm was written by Moses? If it was, is it possible to know what period of his life this reflects?
*I imagine the options for למשה (lamed + Moses) in 90:1 would be similar to לשלמה (lamed + Solomon) in Song 1:1 that I asked about in another question, but I’m not sure about that.