First of all, I have no idea how this rumour started, but a number of people signaled this already; the rumour sounded something like this:

I was talking to my son last week (he works on Mauna Kea), and he mentioned some new observations (that will no doubt get published eventually) of “Beetlejuice”; it’s no longer round. This is a huge star, and when it goes, it will be at least as bright as that 1054 supernova…except that this one is 520 light years away, not 6,300

Yep, it's this big

Betelgeuse is about 100.000 times bigger than the sun, and “just” 600 light years away, so if it would have gone supernova, it would have been a big deal; although it probably wouldn’t hurt us, it would be an astronomical bonanza like no other ever seen in our history.

I don’t know where this rumour first popped out, but by the I read it, it sounded really vague and not quite trustworthy; sounded like something somebody heard from somebody who sort of heard it. It’s also not true, at least according to the man who runs the observatory on Mauna Kea. According to him:

Betelgeuse will go supernova within the next 100,000 years, so the odds against it doing so in the next year are 100,000-to-1. We have no information about “recent” observations of Betelgeuse collapsing. It’s actually quite unlikely that Betelgeuse would have been targeted for observation in the last month or so, as it’s not unfavorably close to the Sun and therefore difficult to observe.