The Solemnity of the Transfiguration of the Lord
is today. There is information on it here.

The day will come at length, when our Lord and Saviour will unveil that Sacred Countenance to the whole world, which no sinner ever yet could see and live. Then will the world be forced to look upon Him, whom they pierced with their unrepented wickednesses; "all faces will gather blackness." [Joel ii. 6.] Then they will discern, what they do not now believe, the utter deformity of sin; while the Saints of the Lord, who seemed on earth to bear but the countenance of common men, will wake up one by one after His likeness, and be fearful to look upon. And then will be fulfilled the promise pledged to the Church on the Mount of Transfiguration.

Venerable John Henry Newman, C.O., Parochial and Plain Sermons