Is the sun the Lake of Fire?

The Lake of Fire cannot be the sun, because the Lake of Fire will exist after the sun and the rest of the Universe has been destroyed:

Rev. 20:11 Then I saw a great white throne and Him who sat upon it, from whose presence earth and heaven fled away, and no place was found for them.
Rev. 20:12 And I saw the dead, the great and the small, standing before the throne, and books were opened; and another book was opened, which is the book of life; and the dead were judged from the things which were written in the books, according to their deeds.
Rev. 20:13 And the sea gave up the dead which were in it, and death and Hades gave up the dead which were in them; and they were judged, every one of them according to their deeds.
Rev. 20:14 Then death and Hades were thrown into the lake of fire. This is the second death, the lake of fire.
Rev. 20:15 And if anyone’s name was not found written in the book of life, he was thrown into the lake of fire.

Notice the heavens and earth (meaning all the universe) are gone in v.11, yet the Lake of Fire still exists following their departure (in vs.14-15). For more information on the Lake of Fire, please listen to our Revelation Bible study online. You may also find the following article helpful: Where is the physical location of the Lake of Fire?