Face-off: PBS moderates on-line debate between proponents and detractors of Younger Dryas cosmic impact

George, great post! I read parts of one totally delightful essay and plan to read more. Would it be possible to invite rebuttals for selected individual entries?? Here is why: Unfortunately, I have become totally prejudiced against certain well-known individuals who actually have my very high esteem, except that I find it difficult not to smell their prejudice. If a rebuttal is available, then reading the original opinion becomes more palatable. This is similar to putting tabasco sauce on slightly gamy meat,

My G*d what a pack of retards. There was no "Clovis People" in the sense of a unified ethnic group. "Clovis" was a point technology rapidly adopted by many different peoples. A very good example of cultural diffusion, in fact.

What is bizarre is that data from the Moon is used to estimate Earth impact rates, while Earth impact data is conveniently not gathered, ignored, or suppressed. Even for the geologically recent past where we have large craters, what hit is not known. Earth-Moon is a 2 body system. We don't know if the Earth and Moon were impacted at the same rate, or if the Moon took some of the hits for Earth, or if the Earth took some of the hits for the Moon. I'd go with option 3, based on the way Jupiter takes cometary impacts. I could go on about the spectral sensors and analysis of data sets for other planets, but instead just let me state that in my opinion NASA's Ed Weiler needs to be "relieved", as this is the only way that any NASA co-ordination on this hazard with other federal agencies will be possible.

Ed, interesting comments there all of it. Would you suggest that the Shoemaker-Levy/9 was an accidental discovery that happened to be a first but that there were many other Jupiter cometary impacts like it at earlier times that escaped human notice simply because we didn't have a space telescope and fewer/ smaller/ or no Earth-based ground telescopes in pre-Galileo times? My guess, after reading your comment, is that Chinese and European naked-eye observers might have missed dozens of comet impacts on Jupiter while observing the night skies in those early days.

Ed - Good and very informed comments, as usual. Weiler must be a real prat. Hermann - Your guesses about S-L/9 are good ones, IMHO. My first impression is that they simply weren't looking before. We don't have any telescope trained on Jupiter, as a matter of course, do we? And if a lesser number of fragments had hit in a shorter amount of time, it seems they could have fallen in between the cracks (literally in between those windows of observation). I am addressing recent times, of course. In older times, a billion large impacts could have taken place in historical times, and no one would ever have known.

BTW, I can't get the NOVA links to work.