If you’re reading a religious history blog–which you obviously are–you’ve probably heard of the hollow earth theory–but have you heard of the hollow sun theory? The theory, though he never gave it a name that I’m aware of, was developed by Latter-day Saint Esaias Edwards (1812-1897). Edwards converted to the Church of Jesus Christ of Latter-day Saints in Missouri after becoming convinced that the Church most closely resembled the biblical church and after the miraculous healing of his wife by a Mormon elder. He shortly after moved to Nauvoo and eventually on to the Great Basin. His diary recounts his desire to start a family cooperative community called “Edwardsville” where he would bring together the members of his family, most of whom had not converted to Mormonism, and where he would not only greatly improve all of their lives materially but would be enabled by the inspiration of God to teach them more about science, astronomy, and religion than any other person could.
In his diaries Edwards lets his speculations on the location of the celestial world on the sun run wild. It is a fascinating read. Basically, he suggests that the sun is the habitation of celestial worlds. The sun is hollow-what we see is the “outer curtain,” which gives light and warmth to all the planets. The dark solar spots, which many had heard of at the time, were openings that would allow sanctified planets to pass through the curtain. All planets are created at a great distance from the sun but are drawn nearer to it as they progress in righteousness. When they are perfected such worlds and their inhabitants are fireproof and can dwell in everlasting burnings.
A vestige of this idea–that of the sun being literally, not only symbolically, the celestial kingdom–persisted in some strains of Mormon thought. In a letter Joseph Fielding Smith wrote to his missionary son, he expressed his belief that the sun was actually the heavenly habitation:
It is my judgment and belief that the sun is a celestial body. It has previously passed through its death and had its resurrection, just as it is decreed that this earth shall do. No man ever saw the face of the sun, so far as I know, for it is surrounded by a cloud. This cloud is what the astronomers see. It is very apparent during an eclipse, but the sun is veiled so that we cannot see its surface. Moreover, I believe that it is inhabited. Why not? If we ever have the privilege of dwelling on a celestial earth–and this earth will become such–we will have to endure “everlasting burnings.” 
 The hollow earth theory has taken many forms over time, many purporting that the lost ten tribes are located within the earth somewheres, getting there, I suppose, through a tunnel in the north country. A variation on the theme, and one of the most elaborately developed, was that by Cyrus Teed, leader of the Koreshan community, who stated that the earth is hollow and we are living on the inside.
 Edwards’s diary is housed in BYU Special Collection, and a scanned copy is located in the Trails of Hope database, available thru the library catalogue.
The idea that the earth will become a sun is also found in some strains of theosophy.
 JFS to Milton Smith, July 18,, 1948, qtd. in Joseph Fielding Smith Jr. and John J. Stewart, The Life of Joseph Fielding Smith(SLC: Deseret Book, 1972), 295.