Sundial (weapon)

Sundial was the codename for one of two massive nuclear bombs planned for testing by the University of California Radiation Laboratory's Livermore Branch, part of a classified American weapons project in the early 1950s. The Hungarian-American physicist Edward Teller announced it in 1954 to the Atomic Energy Commission's Man Advisory Committee, describing a design intended to yield 10 gigatons of TNT. Had it been built and detonated, Sundial would have produced a fireball up to 50 kilometers across, ignited everything within 400 kilometers instantly, and triggered an earthquake of roughly magnitude 9, with the explosion expected to bring on an apocalyptic nuclear winter. The weapon was never built.