The "Gayatri" Mantra is actually a misnomer. Perhaps it should be called the Savitri Mantra, that is sung, or chanted, in the Gayatri metre. But irrespective of the name that we use to refer to it, it is fact that it is the most significant string of characters that is central to the Hindu way of life. From Kashmir to Kanyakumari, from Kamaksha to Kathiawar, this is one set of words that are universally recognised and held dear by the Hindu population or at least the scholarly and priestly class.
It is of course a different matter that this string of characters is almost impossible to translate into English or even any other Indian language. The syntax, the sequence of nouns and verbs, incredibly archaic ... and yet for those who can feel its throb in the echoes of the heart it is quite clear and lucid ... but of course inexpressible in a language other than the native Sanskrit.
I found this translation, which is first literal and then allegoric, to be the closest to what it perhaps means.