VY Canis Majoris is a hyper giant star, one of the larger known stars. If this star was placed where our Sun was, it would extend out past Jupiter. The star is loosing mass due to its low surface gravity and extreme stellar wind, and is surrounded by a envelope caused by the mass loss. Due to its extreme size and mass, for a star, it will have a short lifetime and probably will go supernova within 100,000 years.
Annotated image follows.