Yeah, for those of you who did in fact not only believe this bullstuff, but at the same time think that if a star did go supernova it'd be bright enough to be like a second sun?
Here, let's think of it like a third grade science experiment, shall we?
Say lightyears don't really matter and that light could travel instantaneously but still within the guide of regular space, meaning we could see the light the same time of it's emission but it's still the same distance.
So now lets think that I have a flashlight. You're standing on the other side of a dark field at night and trying to read a book. I offer to give you some help with that, but I don't actually move, I just turn on the light. Sure, you can see it, but that doesn't mean you'll be able to read your book.
Betelgeuse, in that "no lightyears" situation is like my flashlight. Assuming it didn't take years to get to earth, if it exploded tomorrow and we could see it the same time it exploded, it'd be noticeable, but it would not look anything like a second sun.
Now, admittedly I'm no scientist, but really this should just be common sense. And for an added bonus, let's quote an actual scientist:
The supernova would hit somewhere around the brightness of a crescent moon.
The story would be much more accurate if it said "second moon."
