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1.媒體來源:
bbc

2.記者署名:
Jonathan Amos

3.完整新聞標題:
Dinosaur asteroid's trajectory was 'perfect storm'

4.新聞連結:
https://www.bbc.com/news/science-environment-52795929

5.完整新聞內文:
Prof Collins is part of an international team that's been studying the
anatomy of the crater associated with the calamitous asteroid strike.

Today, this 200km-wide structure is positioned under Mexico's Yucatan
Peninsula, with its best preserved central portions sitting just offshore of
the port of Chicxulub.

It's hard to grasp the scale of the forces that produced it.

The impactor, thought to be about 12km in diameter, punched an instantaneous
hole in the crust that was probably some 30km deep. As fluidised rocks at the
base of this bowl rebounded, they created in just a few minutes a mountain
that was higher than Everest. This didn't last, however, and it fell back, to
leave a prominent inner ring of hills, or peaks.

What's interesting from Prof Collins' perspective is the asymmetry that was
frozen into the Chicxulub structure.

For example, if you look at the centres of the crater, of its peak ring and
of the uplifted rock that underlies the crust in Earth's mantle - these
points do not map directly on top of each other. They're actually aligned in
a northeast-southwest direction, with the crater centre in between the
centres of mantle uplift and peak-ring formation.

This is a vital clue in determining not only the direction from which the
asteroid arrived but the angle at which it hit the planet.

The Imperial researcher ran a number of simulations on the UK Science and
Technology Facilities Council (STFC) DiRAC High Performance Computing
Facility. The only way he can reproduce the geometry is by having the
asteroid come in from the northeast and strike the Earth at an angle of
roughly 60 degrees.

Prof Collins said: "If you run the model at different impact angles, at 30
degrees and at 45 degrees, say, you can't match the observations - you get
centres of mantle uplift and of the peak ring on the downrange side of the
crater centre. And for a straight overhead impact, at 90 degrees, the centres
are all on top of each other. So, that's doesn't match the observations,
either."

Imperial colleague and co-author Prof Joanna Morgan added: "Knowing the
direction of impact means we now know which part of the target site was
subjected to the greatest shock pressures.

"The sulphur-bearing and carbon-bearing sedimentary rocks actually thicken as
you go from east to west, and to the south. So this result means we're
degassing more of those sediments than we would if you just took an average
value for their thickness."

And Prof Sean Gulick from the University of Texas at Austin, US, told BBC
News: "This new modelling provides a clear answer to the angle of the impact
and the direction of the impact that largely settles a long-standing debate
on what was downrange of the impact.

"Also critical is that a 60-degree angle is in the range of the worst options
for injecting large volumes of vaporised and ejected sulphur-rich rocks into
the atmosphere.

"Thus these results are critical for understanding potential 'kill
mechanisms'," the co-author explained.

Gulick and Morgan led the expedition that drilled into the Chicxulub Crater
in 2016 to recover some of its rocks for an analysis. A follow-up,
high-resolution seismic survey is due to take place late this summer that
will provide an enhanced 3D view of the structure.


Scientists now think a 12km-wide object struck Earth 66 million years ago

The crater it produced is about 200km wide and is buried mostly offshore

On land, it is covered by limestone, but its rim is traced by an arc of
sinkholes

Experts drilled into the crater to study its rocks and reconstruct the event

They say the impact was more than capable of driving a mass extinction


6.備註:

最近倫敦帝國大學的研究顯示

當初砸死的恐龍的隕石異常完美

完美的大小 完美的軌道 完美的角度 完美的落地點

目前正在研究將來是否會有類似災難發生


也就是說恐龍應該是雖亡猶榮了!?

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