VY Canis Majoris

(VY CMa) is a red hypergiant star, located in the Canis Major constellation. It is one of the largest and brightest known stars. At the time it was the greatest known star, but then other larger stars were discovered. Currently the biggest star known is UY Scuti

There are two different opinions regarding VY CMa. One of them is that the star is a huge and luminous red hypergiant, which initially has been assumed with a radius between 1800 and 2200 solar rays — in which case its surface would extend, if it were located in the place of the sun, beyond the orbit of Saturn — , existing estimates of its diameter that consider it even bigger, with a radius of 19 astronomical units, which is equivalent to 3000 solar rays, well above the maximum radius that according to the models can have a red supergiant star. The other is that the star is a normal supergiant, with an estimated radius of 600 solar rays.

Comparison between the sizes of the sun and VY Canis Majoris.
The latest measurements suggest that your radio is 1420 ± 120 times that of the sun (i.e., similar to other red hypergiants such as Mu Cephei or V354 Cephei and within what the theories of stellar evolution predict). Its luminosity (assuming a radius of 1420 times that of the sun) is approximately 300 000 times higher than that of our star.