Have any prominent theologians written on what the ascension looked like?
Dr John Gill, Particular Baptist, commented that although it is not noted in either testament, Jesus' ascension must have been accompanied by "a shout, with the voice of the archangel & with the Trump of God" (1 Thess. 1:16) because He is said to return "in like manner" (Acts 1:11). I have misplaced the source for this if anyone wishes to add the source please do. Similarly, Augustine of Hippo stated that He must return on a cloud as that is how He departed. I personally dont find either inference to be cogent but these were eminent theolgians.
What we are informed about as to the appearance of the Ascension is that it occurred in a deliberately secluded location, Bethany (Luke 24: 50) having walked over the summit of the Mount of Olives a further 1 1/2 miles and 600 feet lower to Bethany, which was completely out of sight of Jerusalem. Further he was accompanied only by His closest 11 disciples (Judas being dead & Matthias not yet chosen) & only whilst He was disappearing was their wonderment & reverie interrupted by the "two men in white" (Acts 1:10,11) whom some commentators believe to be Heaven's witnesses, Moses & Elijah (cf. Rev.11:3; Zech.4:14; Matt.17:3;Luke 24:4)
Hence we may glean something of what the Ascension looked like. As with Christ's Post Resurrection/Pre-Ascension ministry it was a very private affair without fanfare & restricted solely to believers. And we are informed that Jesus will return or "shall so come in like manner" (Acts 1:11).