The sun getting bright is different than a meteorite impact. The latter has a Poisson distribution; a big one could hit next year, and the one following that in 10, but it also could be many thousands of years before the next big hit.<p>On the other hand, if our understanding of astrophysics is even remotely correct, the sun will not get too bright for the first 100,000 years. So, it makes perfect sense to not worry about the sun now, as it will not happen soon.<p>As to the limit: the Dutch design their sea defences for “once in a 10,000 year” events and their river defences for “once in 1,250 year” events (<a href="http:&#x2F;&#x2F;www.larouchepub.com&#x2F;eiw&#x2F;public&#x2F;2005&#x2F;2005_30-39&#x2F;2005-39&#x2F;pdf&#x2F;43-47_38_ecodutch.pdf" rel="nofollow">http:&#x2F;&#x2F;www.larouchepub.com&#x2F;eiw&#x2F;public&#x2F;2005&#x2F;2005_30-39&#x2F;2005-3...</a>, <a href="http:&#x2F;&#x2F;blog.longnow.org&#x2F;02011&#x2F;03&#x2F;09&#x2F;the-10000-year-storm&#x2F;" rel="nofollow">http:&#x2F;&#x2F;blog.longnow.org&#x2F;02011&#x2F;03&#x2F;09&#x2F;the-10000-year-storm&#x2F;</a>)<p>I also expect some governments have spent time thinking of what to do in case of impending “once in 500 million years” events (probably lumped together with all smaller ‘end of life on earth’ events. The big question here will be: (when) do you tell the public?)