Betelgeuse is a huge star as can be seen from this graphic from Astronomy Picture of the Day for 1/2/20.

It is so huge it can be imaged from Earth-based telescopes.

Between January and December last year the appearance of the star changed and it also became dimmer. Whether this is a prelude to its imminently going supernova (as it will one day) is a matter for discussion.

Photos from Astronomy Picture of the Day for 17/2/20