

Dinosaur-killing space rock 'was a comet' - momchenr
http://www.bbc.co.uk/news/science-environment-21709229

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Lost_BiomedE
"...the team suggests that frequently quoted iridium values are incorrect.
Using a comparison with another extraterrestrial element deposited in the
impact - osmium - they were able to deduce that the collision deposited less
debris than has previously been supposed...The recalculated iridium value
suggests a smaller body hit the Earth."

I don't know if this instance is the case, but I have noticed a few instances
where false knowledge is repeated for years. The ones that I have noticed have
been due to researchers being lazy or too rushed to look at the primary
source. It always makes me wonder what else we have not yet corrected. The
viscosity incident that Feynman mentioned, while different, also freaks me
out. See:
[http://en.wikipedia.org/wiki/Oil_drop_experiment#Millikan.27...](http://en.wikipedia.org/wiki/Oil_drop_experiment#Millikan.27s_experiment_as_an_example_of_psychological_effects_in_scientific_methodology)

Example: A cup of green tea is often said to contain 125-250mg of egcg. While
this is true for a gram of sencha or matcha, where the whole leaf is ingested,
a hot water brewed tea provides more than an order of magnitude less. Sencha
and matcha were measured by ethanol extract, simulating leaf ingestion. But
for about a decade now, the original source is not cited but other papers
claiming water brew to contain >100mg. If you follow the trail all the way
back to the original source, you can see that one person misread the paper and
started this false knowledge. It is something I think about a lot when
validating my own references.

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pstuart
Don't forget to drink your 8 cups of water each day....

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pavel_lishin
It's great for washing down spinach.

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swombat
_But other researchers were more cautious about the results._

Well, I'm glad the headline made that clear.

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teeja
Really. This has gotten to be a serious problem with science-reporting lately.
Headlines suggest deterministic certainty, article itself says, for example,
"probably a speeding comet, US scientists say." (Not even "some US scientists"
or "hypothesize".)

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guard-of-terra
As far as I know, while astronomers are fairly sure that it was a giant space
rock that killed dinosaurs, biologists/paleontologists are more wary.

Some of big dinosaur findings are well after the iridium anomaly - meaning
some dinosaurs managed to survive the impact.

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ImprovedSilence
Indeed. I don't have any sources off hand, but I believe the extinction lasted
tens of thousands of years. And was only partially set off/caused by the
impact. There have also been other mass extinction events, each lasting long
periods of time on the "lifetime" scale, but are still just "relatively short
periods of time" on a geologic scale.

[edit] here's some good reading for you:

<http://en.wikipedia.org/wiki/Extinction_event>

and the event discussed in the article:

[http://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_ex...](http://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event#Alternative_hypotheses)

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youngerdryas
More likely is it was a binary

[http://www.newscientist.com/article/dn23126-dinosaurkilling-...](http://www.newscientist.com/article/dn23126-dinosaurkilling-
asteroid-was-a-twin-terror.html)

15% of near earth objects are binaries, a fact that is not widely known.

Edit: asteroids --> objects

