It's a red hypergiant, one of the largest known stars in the universe. While it's not the brightest star we can see from Earth, it emits an enormous amount of light energy, making it the most luminous known star.

Here's why:

* Size: VY Canis Majoris is vastly larger than our Sun, with a radius estimated to be 1,800 times greater.

* Temperature: Despite being a red star, it's still extremely hot, with a surface temperature around 3,000 degrees Celsius.

* Luminosity: This combination of size and temperature leads to an incredibly high luminosity, thousands of times greater than our Sun.

It's important to note that measuring the luminosity of distant stars is a challenging task. While VY Canis Majoris is considered the most luminous known star, it's possible that even brighter stars exist that we haven't yet discovered.