something I don't get about asteroid and meteor impacts

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If what paleontologists believe is true about the extinction of the dinosaurs, a 6 mile wide rocky body struck the earth at the Yucatan Peninsula in south east Mexico.

I guess I'm not completely grasping how a meteor so small in comparison to a planet could cause such devastation. I mean, it's like a grain of sand hitting a basketball.

That rock was going at 60,000 mph. Review the formula for kinetic energy.

The impact produced the energy equivalent of over a billion 50 megaton H-bombs. The effect was to heat the atmosphere and kick a lot of particulate debris into the stratosphere.

The effect of the darkness produced by dust and debris in the atmosphere for ten years was the death of plant life which live by sun light photosynthesis. When the plants died, most of the animals died.

ruveyn

Of course, ruveyn is correct. I asked a similar question about the notion that the volume of water behind Three Gorges dam in China would cause the planet's axis to wobble. The true scale and proportion or difficult to understand intuitively, but scientists can calculate this stuff to a gnat's whisker.

if the earth was without atmosphere, say like mercury, then the collision would not have meant much to earth. i have been to the crater in northern arizona and it is really fascinating. the circular debris field of giant boulders confirms it was an et body. anyone in the southwest should see this. to the earth-----a tiny pimple.

a rock 100km in diameter going 100,000km........think of the literally trillions of tons of rock and fine dust. trapped in the atmosphere for a long time. no sun. sorry about parroting ruevyn.

there are other theories, the worst spouted by creationists.

...At an extremely high speed. It's not just the size that determines how devestating the impact is; it's the amount of energy transferred. Compare it to a bullet. If you throw a bullet at someone, then they won't be hurt very badly. But if you shoot that person with the same bullet from a gun, it can kill them.

kinetic energy is equal to 0.5 times mass (kilos) times the velocity (meters per second) times velocity.

KE = 0.5 mvv

So if v is high then KE can be very large.

As well as kicking up a lot of dust, a large nuclear bomb will inject a lot of nitrogen oxides into the ozone layer. I suspect that the heat of the fireball of a big rock hitting the earth would also create NOx and the heat of the impact would inject this into the upper atomsphere. Where I imagine that the reduction of the ozone concentration would make the UV level at sea level go up a lot. This would tend to kill off those plants which managed to survive the "nuclear winter". I am not sure how long the ozone layer would take to recover from a large dose of NOx.

I know this is kind of off-topic, but how many users are there on this forum with Mutt logos for their avatars?

thanks folks! That explains it much better

Along similar lines, small particles of space debris could be very dangerous to the ISS or the shuttle while in orbit, because of their respective speeds.

The biggest problem with accepting the Yucatan Chicxulub crater as the primary cause of the mass extinction at that time is why were amphibians and crocodilians able to survive when they have been show to be highly sensitive to minute changes in environment. Climate changes or disease are dismissed when they been shown to have a bigger influence on evolution than random castastrophes.

why having a time machine would be.....oh, so handy.

i'm fairly out of touch with reality, but , if mutt in this context means dog....well, i am a dog sort-of, my veterinarians tell me i was raised by wolves. sad.......but true.

Mutt is a terminal-based email client. I have it on my Linux box, and its icon in my applications menu is the same as your avatar.

Maybe the amphibs were tougher 65,000,000 years ago.

ruveyn

Keep in mind also the massive fires that the impact would have started across the proto-North-American continent, during an era when Earth's atmosphere had more free oxygen than it does today...

Crocodilians are not dinosaurs - they are reptiles which descended from dinosaurs. Some life forms were able to adapt in time - the therapods, for instance, would seem to be ancestor to modern birds, the feathers being an evolutionary adaptation to changing temperatures. Further, water living seems to cushion environmental effects on evolution (cf sharks and coelecanths).

Amphibians- the ability to breathe underwater might explain part of that. Water retains heat better than air. Also being able to live in the air and underwater made sure it had a food supply.

As for Crocodiles- They eat just about anything and being cold blooded needed less food to survive

amphibians breathe air. They spend part of their life cycle in the water and the other part in or near the water but they don't breathe water.