A Dyson sphere is a hypothetical megastructure an advanced civilization might build around a star to capture much of its energy, proposed by Freeman Dyson in 1960. A full shell is likely unstable, so most concepts envision a swarm of orbiting collectors. Such a structure would dim and redden its star in a distinctive way, which briefly made Dyson swarms a candidate explanation for the strange dimming of Tabby's Star before dust proved the better fit.