The verb diaugazō describes light penetrating through and illuminating — the dia- prefix suggesting light shining completely through. It appears in 2 Peter 1:19 in the promise that the day will dawn and the morning star will rise in believers' hearts as they attend to the prophetic word.
Peter's use of diaugazō for the dawning of the day paints a breathtaking eschatological picture: the darkness of this age is being pierced by the sure prophetic word, and the full dawn — the return of Christ, the Morning Star — is coming. This encourages patient, attentive engagement with Scripture as the light that guides us through the 'dark place' of this age until the light bursts through completely.