More Evidence Supports Massive Asteroid Strike 84
InnerPeace Volunteers writes "From a BBC Sci/Tech article: The idea is that a giant asteroid about 10 kilometres wide, travelling at 90,000 km/hour slammed into the Earth at the southern margin of North America. This was a case of global devastation rather than North American catastrophe. The asteroid devastated pretty much everything."
Yellow journalism (Score:2, Informative)
So they say they found a bunch of bones that suggest "major disturbances in climate that led to the death of most trees and flowering plants." Why does that sort of stuff always lead toward an asteroid that there is no _direct_ evidence of?
This is what I call yellow journalism. It is there opinions and beliefs that are reported and taken as truth.
News flash: It's good for you health to eat saturated fatty foods. The large fat globules travel through the blood vessels and break up smaller globs stuck to the insides of vessels.
BTW: What does this have to do with nerd news? Are there some archeological nerds out there that go to /. for their news?
Re:Yellow journalism (Score:2, Informative)
Re:Yellow journalism (Score:2, Informative)
Crater Size Calculator (Score:3, Informative)
http://www.lpl.arizona.edu/tekton/crater.html
Which let's you calculate the estimated diameter of the crater a body of a given size, given density, given speed and given impact angle will make on different targets. (Or reverse that and estimate the diameter of a body that creates a crater of a given size).
Accoring to this a 10km body with the density 3t/m, speed of 25km/sec (=90000 km/h) will create a crater with a diameter of ~216km when it hits Earth in an area of "compent rock or saturated soil" (target density 3t/m).
Re:Yellow journalism (Score:3, Informative)
I call this direct evidence. Your mileage may vary.
Re:What you say? (Score:4, Informative)
This actually was a big thing a few years ago. Thus you have goodies like the Sky and Telescope Impact Hazards website [skypub.com], along with this nifty cosmic impact calulator [umd.edu].
To be fair, there is this article about a scientist that thinks mass extinctions are a myth [spacedaily.com]. ( I am skeptical of this.
And not that a ten mile wide asteroid would make a mess, but that an asteroid needed to wipe out and actually destroy the earth would likely be much much large, maybe 1,000 miles across or more.
10 miles across is like a bug on the windshield. Note that humans are living on the outside of the windshield.
So it sounds like you get to have fun researching impact craters on google, etc.
Re:"Suddenly disappeared..." (Score:2, Informative)
The hypothesis that birds are dinosaurs was actually proposed early in the 1800's. The reaction of lots of scientists was the usual "That's an intriguing idea; where's your evidence?" It took more than a century for people to stumble onto convincing evidence. Most of the best evidence has been found in the last 30 years or so. Birds don't fossilize too well. Also, it seems that most of the few good bird fossils are in China, and political problems prevented much serious paleontological work there for a long time.
Also, it wasn't just frogs and salamanders that survived. Several species of mammals managed to hang on until things got better. This included a small tree-shrew-like proto-primate.
Re:gulf of mexico (Score:2, Informative)
Of course, in many scientific circles, "fossil" is routinely used to refer to any distinct objects or materials found in rocks. The term doesn't just mean remains of once-living organisms. Thus one reads of bits of "fossil gases" entrapped in cracks or bubbles in rocks or ice; these are used to learn about ancient atmospheric conditions. Sedimentary strata contain "fossil rock" as tiny inclusions. And so on.
But still, 4.5 billion years ago, the Earth didn't have much in the way of solid crust, and most of that has long-since been subducted and melted. So we may never have many details from back then. This makes it a bit difficult to find data for or against the "colliding planets" hypothesis. The best argument so far isn't fossil at all. It comes from physicists' attempts to explain how a pair of planets so closely matched as the Earth and its moon can end up in the orbits that we see today. Orbital mechanics seem to preclude this, except as the outcome of a grazing collision between two planet-sized objects.
As a separate subject, though, geologists do say that even if this collision happened, it probably has little if anything to do with the formation of the Pacific Ocean. From what has been learned of plate tectonics in the past decades, it seems that oceans and continents have come and gone many times. The presence of such a large, circular ocean at this time is somewhat of an accident, and wasn't really true at several times in the past billion years.
Gotta go