Star with a comet's tail

This is really (geeky) cool ... but apparently a NASA telescope just spotted a comet-like tail on the star Mira, a star that has been studied for about 400 years. The article has a very cool picture, but what I'm having trouble wrapping my mind around is the concept that "in fact, material blowing off Mira is forming a wake 13 light-years long, or about 20,000 times the average distance of Pluto from the sun." 13 light-years long? My mind just can't grasp that at all ... wow! I know, I'm a big nerd.