UY Scuti is a red supergiant star in the Scutum constellation. It is one of the largest known stars by radius at 1,708 ± 192 solar radii, corresponding to the diameter of 2,375,828,000 kilometers. If placed at the center of the Solar System, UY Scuti can engulf all the planets all the way to Jupiter, filling more than halfway through Saturn’s orbit. It has a volume approximately 5 billion times that of the Sun.
It is one of the extreme luminous supergiant stars and a semiregular variable star with a period of about 740 days. The star is almost totally obscured by dust and gas, with very high mass loss due to low density and high luminosity, similar to the smaller red hypergiant star VY Canis Majoris. Due to this its true size is still debated and may have a diameter smaller than the current estimate.