Wednesday, September 5, 2007

Dinosaur Extinction Culprit Found: Baptistina

New Scientist has reported that David Nesvorny and his colleagues from the Southwest Research Institute have apparently found the asteroid that pummeled earth nearly 65 million years ago according to some estimates. This asteroid has been labeled the dinosaur killer.

Here is a quote from the article:
Nesvorny's team has calculated that a 10-kilometre asteroid, one of roughly 300 chunks of the original 170-kilometre 'mother rock', would have collided with the Earth. Other fragments of this asteroid may have hit Venus, they suggest, and could have been responsible for the formation of Tycho, the youngest prominent crater on the Moon.

You can read more here or read the SRI paper here (which shows it as being released tomorrow: the 6th).

Some questions:
-What are your thoughts about some of the facts and figures being surrounded by qualifiers such as "may have", "could have", "suggests"?
-How could one construct a model to show that this group of rocks is what is left of the one rock that struck the earth somewhere 65 million years ago and wiped out life as it was known back then?
-How could one even trust dating methods to go back so far?


B Nettles said...

Actually, the dating methods used these days are very sophisticated, consistent, and self-checking. And they aren't using Carbon-14 for this. They depend one the ratios of several different isotopes, both stable and radioactive, and have demonstrated consistent results independent of the origin of the rocks. They don't depend on hypothetical starting ratios because there are 2 ratios involved. That's the self-checking part. In developing these methods, the scientists are trying to eliminate as much "guessing" as possible. They do depend on consistent decay rates of the radioactive nuclides, but no one has ever demonstrated that the nuclear decay rate of a particular nuclide (a single type of nucleus) varies, and there is no a priori reason to expect it to. In fact, the decay rates are more stable than the earth's motion around the sun, or it's rotation on the axis. It's not a question of whether the method is trustworthy. The question is, what does a number that big mean?

j razz said...

b nettles,

Did you look at the link concerning trusting dates? The book has some polarized reviews; are you familiar with the author?

j razz