In my book Magicians of the Gods I examine the paradigm-shifting evidence for a cosmic impact 12,800 years ago, followed by further cataclysmic impacts 11,600 years ago. The argument, strongly supported by a number of leading astronomers and astrophysicists, is that both these groups of impacts originated from the same source — a fragmented giant comet that entered our inner solar system around 20,000 years ago on an earth-crossing orbit. Like other comets (e.g. Shoemaker Levy 9) it broke up into multiple fragments, some very large some much smaller. Several of these fragments were responsible for the first cataclysm of 12,800 years ago, and several more were responsible for the second cataclysm 11,600 years ago.
The astronomers whose work I review in Magicians of the Gods, are convinced that multiple large and deadly fragments of the same original giant comet are STILL circulating in the Taurid meteor stream, the path of which the Earth crosses twice a year (June/July and Oct/Nov), and pose a clear and present danger to the future of human civilization and perhaps even to all life on our planet. There is no need for gloom and doom. This is a problem that we already have the technology to solve. NASA is in denial, or deliberately concealing what it knows, but the hints keep coming that we are heading for something big. See here for example: http://www.space.com/34070-earth-vulnerable-to-major-asteroid-strike.html. And here: http://www.independent.co.uk/news/science/earth-could-be-at-risk-of-meteor-impacts-and-we-might-wrongly-have-assumed-we-are-in-a-safe-era-a6702501.html. And again here: http://www.space.com/33576-asteroid-defense.html
Then there is this observation of a recently observed increase of the rate of cratering on the Moon. The moon is 384,000 kms distant from us, but the Taurid meteor stream is 30 million kilometers wide. What happens on the moon is therefore an indicator of what can happen here unless we act responsibly, and with foresight, to do something about it: http://www.space.com/34372-new-moon-craters-appearing-faster-than-thought.html
Fortunately some are thinking of doing something about it. I’m not sure we need a “space nation” when we haven’t even scratched the surface of the huge and heartbreaking problems caused by mindless jingoistic nationalism here on Earth, but their ideas about doing something about potential cosmic impacts definitely resonate: http://www.telegraph.co.uk/science/2016/10/12/scientists-propose-space-nation-named-asgardia-and-cosmic-shield/
The linked interview was recorded last year, just before the release of the hardback of Magicians of the Gods: https://www.youtube.com/watch?v=TWmaiexDRGs. The paperback, revised and extended, is now out and available in the UK: https://www.amazon.co.uk/exec/obidos/ASIN/1444779702/theofficialgra0b. More editions of Magicians here: https://grahamhancock.com/magicians/