I shouldn't be surprised. It seems every month or two a new theory about how the Earth will perish in December of 2012 is invented or revived.
What is surprising, however, is how widespread it has become; with several reputable news outlets such as CNN and Time, sourcing a story at the The Huffington Post, lending credence to this garbage particular theory. [Update: Since writing this post I can no longer find the Time and CNN articles. I assume someone clued them in to their error. The Huffington Post article was still live at last check though.]
The theory in question pertains to the eminent supernova that is the star Betelgeuse. You read that correctly, the star will, at some point, go supernova. But will it be in 2012?
The roughly 20 solar mass red giant is near the end of its life, meaning that it will eventually explode in a brilliant release of energy. The problem is, that we really no no clue when it will go supernova. Could be tomorrow. Could be tens of thousands of years from now. Any claim to have knowledge to the contrary is ridiculous.
So, could it happen in 2012? Sure. Will it? Statistically, not likely.
But, what if it did? If you believe the reports floating around in the internet, the exploding star will appear as a second Sun in the day time, and illuminate the night. And, worse yet, the sheer energy from the blast will have devastating effects on the Earth, particularly our atmosphere!
While an exact distance to Betelgeuse is difficult to assess (late stage red giants have tenuous outer envelopes, thwarting traditional attempts to measure distance accurately), our best estimate is that it is about 600 light-years from Earth. This is actually quite close in galactic terms (our Sun is about 8 light-minutes from Earth), so I am not totally shocked how the blogosphere has crescendoed to near panic levels over this.
But instead of panicking, let's do a little back-of-the-envelope calculation. Typically Type II supernova (a supernova resulting from the collapse of a massive star) of this size have a peak luminosity (integrated over all wavelengths) approaching about 1 billion times the power of our Sun. Quite impressive. It sounds like a lot of energy is being generated very quickly and it is. So why am I not worried?
Because the apparent luminosity (effectively the amount of energy that arrives at Earth per second) falls off with the square of the distance. In Laymen's terms, if our Sun were ten times further away from us, its apparent luminosity would be 100 times less.
So given the 600 light-year distance to Betelgeuse (about 40 million times further away from us than our Sun), the apparent peak luminosity of the supernova explosion will be roughly 0.00006% of our Sun's apparent luminosity. Clearly that is such a small percentage that the additional flux will have zero effect on our planet.
What is perhaps more interesting is the optical peak brightness (how it will appear to the naked eye). It should appear noticeably brighter than Venus on a clear night, perhaps significantly so. (I've seen reports that would indicate the brightness might rival that of the full moon, but I am somewhat skeptical of this; the numbers just don't seem to add up in my estimation.) Short story is that it will be noticeable even to those without scientific training.
Reports that are claiming that we will experience a "second sun" for several weeks in 2012 have been grossly misinformed. It may be bright enough to be visible during daylight hours, similar to the way the moon can be seen under certain conditions during the day. But two Suns? Afraid not.
Ultimately, we are not doomed when betelgeuse decides to go supernova, whenever that may be. But it will be pretty spectacular though. To actually watch the event unfold and monitor the aftermath of such a nearby source will be a huge boon for astronomy. I, for one, hope it happens sooner than later. I'd love to be around for it!
Image Credit: NASA, ESA