
Dinosaur-Killing Asteroid Could Have Caused 2 Years of Darkness - okket
http://astrobiology.com/2017/08/dinosaur-killing-asteroid-could-have-caused-2-years-of-darkness.html
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excalibur
> While the scientists think the new study gives a robust picture of how large
> injections of soot into the atmosphere can affect the climate, they also
> caution that the study has limitations.

> For example, the simulations were run in a model of modern-day Earth, not a
> model representing what Earth looked like during the Cretaceous Period, when
> the continents were in slightly different locations. The atmosphere 66
> million years ago also contained somewhat different concentrations of gases,
> including higher levels of carbon dioxide.

> Additionally, the simulations did not try to account for volcanic eruptions
> or sulfur released from the Earth's crust at the site of the asteroid
> impact, which would have resulted in an increase in light-reflecting sulfate
> aerosols in the atmosphere.

Additionally, the "world-class computer model" in which the simulations were
run may or may not have been a Minecraft server.

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sogen
How can they publish something so wrong?

Also: Get off my server

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SapphireSun
Before decrying how wrong it is, try estimating how much those effects matter.

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roceasta
I think our present space technology research focus should be on these
asteroids. Both how to deflect them (peacefully) and how to mine them for rare
metals.

If I read this table correctly it seems that only eight days ago a fairly
chunky rock passed within 60,000 miles of us:

[https://cneos.jpl.nasa.gov/ca/](https://cneos.jpl.nasa.gov/ca/)

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credit_guy
Really cool link, thank you. I think you are referring to the 2017 QP1
asteroid that was closest to us on 14-Aug. the distance was about a sixth of
the distance to the moon, or 38k miles. The speed was 24km/s and the diameter
37-83 meters. Just for fun I ran the Impact Earth calculator to see what would
happed if such an asteroid hit Earth. Assuming the worst case scenario (iron
meteorite, max diameter, perpendicular hit) the explosion would be equivalent
to about 200 MT TNT, and the crater would have a 2 mile diameter and 2000 foot
depth.

Edit: changed mph to km/s

[https://www.purdue.edu/impactearth/](https://www.purdue.edu/impactearth/)

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imaginenore
> _The speed was 24mph_

No way. It was 24 km/second.

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credit_guy
Good catch, thanks.

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09bjb
Graham Hancock dedicates at least 10% of his most recent book "Fingerprints of
the Gods" to exploring the recent evidence for a cataclysmic meteor impact
that catalyzed the precipitous drop in global temperatures we observe 12900
years ago at the "Younger Dryas Boundary."
[https://en.wikipedia.org/wiki/Younger_Dryas#Impact_hypothesi...](https://en.wikipedia.org/wiki/Younger_Dryas#Impact_hypothesis)

He has some pretty out there theories but that section is pretty convincing.

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Retric
My understanding is the duration does not really line up with an impact event
also the starting periods don't seem to line up correctly. "In Western Europe
and Greenland, the Younger Dryas is a well-defined synchronous cool
period.[34] Cooling in the tropical North Atlantic may, however, have preceded
it by a few hundred years; South America shows a less well-defined initiation
but a sharp termination."

Which is what I find annoying about pet theories in books, you can make plenty
of things seem convincing by leaving out other evidence.

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QAPereo
Naively I would assume that if we really had experienced two years of
darkness, avian species would not be here now.

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blacksmith_tb
I do have to wonder how plants could have rebounded from two years without
being able to photosynthesize - you'd think lots of species wouldn't have
viable seeds kicking around at that point. Which would make for some massive
changes to the fossil record for plants. To say nothing of the animals that
depend on them...

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colordrops
Lots of seeds remain viable for more than 2 years.

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QAPereo
It would also have to remain viable in the sense that no animals starving in
the darkness will try to eatthem, or fungus or bacteria running wild. I think
you have to assume that are small burrowing ancestors ate pretty much every
seed they could get their tiny paws on. We know that quite a few different
organisms survived, and while some of them estivated or hibernated most of
them presumably we had to live and eat in a roughly normal way.

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rangibaby
Fungi and bacteria don't like the cold. There would be a lot more food to eat
for survivors (chickens) as things that they competed with for food (T rex)
died off.

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julienchastang
"A world without photosynthesis", "photosynthesis would still have been
impossible for an entire year"

Clearly, photosynthesis did survive in some capacity. No? Life did not re-
evolve photosynthesis in the last 66 million years.

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Xeoncross
Seeds can germinate after much longer than a year:
[https://en.wikipedia.org/wiki/Oldest_viable_seed](https://en.wikipedia.org/wiki/Oldest_viable_seed)

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blacksmith_tb
"Some seeds can live for a long time before germination, while others can only
survive for a short period after dispersal before they die."[1]

I wasn't suggesting all seeds would fail to germinate after two years, just
that some would, and that change would be noticeable in the fossil record.

1:
[https://en.wikipedia.org/wiki/Seed#Germination](https://en.wikipedia.org/wiki/Seed#Germination)

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Xeoncross
Old seeds had much higher germination rate according to the linked wikipedia
article. In addition, cold storage increases the life of seeds. I doubt you
would see much of anything in the fossil record.

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Pica_soO
Fascinating is the feedback loop recovering after the impact. So basically,
all that is needed to bring the sood from the atmosphere down is a long enough
cooling window, binding ice to the dirt.

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brianbreslin
This may be a dumb question, but were all the dinosaurs reptilian and avian?
Were there no mammalian dinosaurs pre-66M years ago? like rodents?

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thanksforcoming
Disclaimer: this is proving hard from me to explain via text without the use
of visualization.

Mammals did not evolve from dinosaurs. Mammals are synapsids, a branch of
tetrapods. Dinosaurs come from a different branch of tetrapods entirely,
called sauropsids. (There is a third branch of tetrapods, amphibia.)

Sauropsida is a really diverse branch containing both extinct and extant
species. Look at the tree at the bottom of the page here [0]. A fork of
interest is Sauria, which splits into lepidosauromorphs (including modern
lizards & snakes) and archosauromorphs. Archosauromorphs have many branches as
well (one of note being turtles), with one that traces far enough to get to
archosaurs [1]. Modern crocodiles come from a branch of archosaurs. Dinosauria
are another branch of archosaurs, and birds are descendants of dinosauria.
They are the only extant species of dinosauria.

The confusion comes because many of these animals co-existed at the same time,
some become extinct, others evolved and change and form new branches (but
still belong to the parent group). The word 'Dinosaur' itself is also
misapplied by the public - it's not all of the animals that lived 65+ million
years ago. It's a very specific group of related animals and all of their
descendants.

TLDR: Mammals didn't evolve from dinosaurs, but from a different branch
further up the chain that dinosaurs also belong to. Those mammalian ancestors
did co-exist with dinosaurs. Like mammals, modern reptiles didn't evolve from
dinosaurs, but from ancestors that co-existed with dinosaurs. Reptiles and
dinosaurs are more closely related than mammals and dinosaurs. Birds did
evolve from dinosaurs, and are the only living dinosaurs today.

[0]
[https://en.wikipedia.org/wiki/Sauropsida](https://en.wikipedia.org/wiki/Sauropsida)
[1]
[https://en.wikipedia.org/wiki/Archosaur](https://en.wikipedia.org/wiki/Archosaur)

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brianbreslin
Thank you for the thoughtful answer.

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mrfusion
I'd be curious how any animals survived.

