A new belt beyond Kuiper's: A belt of focal spheres between 550 and 17,000Â AU for SETI and science

► Gravitational lenses of the Sun and planets. ► Minimal focal distance of such gravitational lenses of the Sun and planets. ► FOCAL space missions to 550 AU and beyond. ► Kraus gain vs. Drake gain for the gravitational lenses of the Sun and planets.