Scarier than an asteroid hitting the Earth!
Whether it's this time or the next or the next, it's inevitable. One of those things that probably won't happen, but if it does will be catastrophic.
With population increases and overcrowding, poverty and unsanitary living conditions, the risk goes up.
Some of the same people that scream about asteroids hitting the Earth and want all kinds of preventative measures about that seem to take a blase attitude toward this much more real threat.
But, no one has ever accused any of 'em of being bright.
Arf