Revelation 16:8

And the fourth angel poured out his vial upon the sun - Toward the sun, or so as to reach the sun. The effect was as if it had been poured upon the sun, giving it an intense heat, and thus inflicting a severe judgment upon people. This corresponds also with the fourth trumpet Revelation 8:12, where it is said, that the “third part of the sun was smitten, and the third part of the moon, and the third part of the stars.” For the general meaning of this symbol see the notes on that place. The idea is, that a scene of calamity and woe would occur as if the sun should be made to pour forth such intense heat that people would be “scorched.” It cannot be supposed that the sun would be literally made hotter, or that the exact nature of these calamities would be that people would be consumed by its rays.

And power was given unto him - To the sun. The meaning is, that a calamity would follow as if such an increased power should be given to its rays.

To scorch men with fire - Literally, “And it was given him to scorch men with fire” - that is, with heat so great that it seemed to be fire. The Greek word - καυματίσαι kaumatisai - meaning “to burn, to scorch” - is used in the New Testament only in Matthew 13:6; Mark 4:6; Revelation 16:8, in all which places it is rendered “scorch” and “scorched.” Compare, however, the use of the word καῦμα kauma, in Revelation 7:16; Revelation 16:9; καῦσις kausis, in Hebrews 6:8; καυσόω kausoō, in 1 Peter 3:10, 1 Peter 3:12; and καύσων kausōn, in Matthew 20:12; Luke 12:55; James 1:11. The notion of intense or consuming heat is implied in all the forms of the word; and the reference here is to some calamity that would be well represented by such an increased heat of the sun.