Comet Research Group

Charlie

The Force is Strong With This One
I watched the podcast of Joe Rogan with just Randall Carlson today. It was pretty interesting. The data he presents for a past cataclysmic event and the ensuing floods that occurred is pretty fascinating.
 

mkrnhr

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Moderator
FOTCM Member
Following the discovery of the Hiawatha Crater in Greenland (and the North Dead Sea impact) this year, comes a very surprising presentation by a long time opponent to Napier, Clube et al.:

Was Tunguska a Beta Taurid? 2019 Observational Campaigns can Test Hypothesis

Hydrocode models of the 1908 Tunguska airburst have provided reasonable explanations for most of the phenomena associated with that event, from the shape of the treefall pattern to bright nights over Europe (Boslough & Crawford, 1997; 2008). Similar models are used for the damage component of probabilistic risk assessment and cost/benefit analysis for planetary defense. Nevertheless, there is still an enormous range in model-based estimates of the size of the Tunguska impactor and explosive yield, from as low as 3 to as high as 20 megatons. This range of possible sizes, combined with the NEO population estimate, leaves us with one unsatisfying conclusion: the Tunguska event was an extreme outlier. The probability of an impact of that magnitude having happened only 110 years ago is extremely low.The frequency of the smallest and largest possible Tunguska-like events should be on the order of once every thousand and ten thousand years, respectively.
One way out of this dilemma is to question a built-in assumption in our probability estimates that small NEOs are effectively distributed randomly. Whereas the most sensational claims of “coherent catastrophism” lack merit, it is reasonable to speculate that the Taurid complex has significant concentrations of Tunguska-sized fragments that are too small to be observed unless in the vicinity of the Earth. Large fireballs--some associated with meter-class impactors--were observed during the November 2015 Taurid swarm return (Spurny et al., 2017). Several small asteroids, such as 2015 TX24, have orbits that are nearly identical to the 2015 Taurid fireballs (Olech et al., 2016; 2017). When the Earth intersects this stream, the impact probability is elevated. If the Tunguska object was a member of a Beta Taurid stream (Kresák, 1978) then the last week in June 2019 will be the next occasion with a high probability for Tunguska-like collisions or near-misses (Asher & Clube, 1993; Asher & Izumi, 1998). Because the Beta Taurids approach from the sunward side, we propose a survey designed to observe such objects after they have passed into the night sky in late June. Fortunately, the Moon will be new on July 3 and will not interfere significantly with such observations. Moreover, the possibility of enhanced daylight fireballs and significant airbursts should be anticipated during that time.
In the Washington Post they "report":
“While we are not predicting another Tunguska airburst, an enhanced population of small NEOs [near-Earth objects] in the Beta Taurids would increase the probability of another such event on or near next year’s Tunguska anniversary,” they concluded.
Well, that will get them some funds.

All in all, it's getting more and more mainstream apparently.
 

mkrnhr

SuperModerator
Moderator
FOTCM Member
Shortly after the discovery of the Hiawatha crater in Greenland, another possible crater is discovered nearby:

For now,
Although the newly found impact craters in northwest Greenland are only 114 miles apart, they do not appear to have been formed at the same time. From the same radar data and ice cores that had been collected nearby, MacGregor and his colleagues determined that the ice in the area was at least 79,000 years old. The layers of ice were smooth, suggesting the ice hadn’t been strongly disturbed during that time. This meant that either the impact happened more than 79,000 years ago or — if it took place more recently — any impact-disturbed ice had long ago flowed out of the area and been replaced by ice from farther inland.
but at the same time:

"This does not rule out the possibility that the two new Greenland craters were made in a single event, such as the impact of a well separated binary asteroid, but we cannot make a case for it either," said William Bottke, a planetary scientist with the Southwest Research Institute in Boulder, Colorado, and co-author of both MacGregor’s paper and the new lunar impact record study.
The original paper is best accessed here: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2018GL078126
 
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