Which of these stars is the largest?

The story behind the answer

UY Scuti is widely cited as the largest star by radius among these options. It’s an enormous red supergiant/hypergiant in the constellation Scutum, often estimated to be roughly 1,700 times the Sun’s radius—big enough that, placed at the center of our Solar System, its outer layers would reach past Jupiter and approach Saturn. That outscales Betelgeuse and the other contenders like VY Canis Majoris and RW Cephei.

Measuring such stars is tricky because their bloated, dusty atmospheres and pulsations blur their edges, but UY Scuti typically tops the list in star-size catalogs. Memory tip: “UY = Ultra-Yuge Scuti.” This helps recall that among famous red supergiants, UY Scuti is the one that’s truly colossal.