(I would like to see the source, too, because I’ve never heard this theory.)

Again, I’m not saying it’s incorrect, I’d just love to read the source because I can’t comprehend how that would happen. Are you sure the atmosphere didn’t get trapped or converted into some other material on the planet, and that’s what happened to it? For example, plants stored a bunch of carbon, and dinosaurs ate the plants and the carbon got trapped underground, becoming oil. If we humans weren’t pumping the stuff up and burning it the carbon would have been lost to the ages. Could the oxygen and nitrogen in the air at the time of the dinosaurs have been ignited in this asteroid strike, and end up being stored at the bottom of the sea, or something?

I just don’t see how you get half the atmosphere to jettison into space without a relatively huge object hitting the planet. One that is 20% or more Earth masses.

-fritz-

Why do I have to keep approving your comments?

*I accidentally typed “Frotz” first, which was weird for an Infocom fan.

To be honest, I can’t remember the sources off the top of my head. A couple of them were things I learned in lecutres in college way back in the 20th century when it was fairly cutting edge, the rest I’ve picked up here and there. I’ll see what I can dig up by way of specific references, though.

As to loosing a lot of our atmosphere, here’s a vastly oversimplified example: You’ve got a bucket of water filled to the brim. You hurl a brick in to it. Lots of water sloshes out, and when things settle down, the bucket is less full than it was before. Our atmosphere is down here at the bottom of our gravity well along with us. If there’s a big enough impact, however, it can ‘splash’ substantial portions of the atmosphere high enough that it essentially escapes the gravity well and dissapates in the vaccuum of space. Presumably, atmosphere that is tossed out with insufficient velocity to escape the gravity well would eventually fall back to the earth.

To be honest, I don’t pretend to understand how one asteroid could do that, but one interesting possiblity that probably accounts for some of it is that you’ve got a global shockwave spreading out from the point of impact and eventually converging on the point exaclty opposite the point of impact. So the air there would be increasingly super-compressed, and may well have geysered off in to space, some of it, anyway. I expect the results of a planet-wide firestorm would probably up the energy level, too, but I don’t know any of that for sure.

I totally agree that it was the denser atmosphere that allowed for massive, jumbo-sized animals and huge insects lacking lungs. I’ve wondered about that m’self.

Stats. from Channel 8, CBS affiliate:

Las Vegas Climate Data: July 1, 2009
Average High: 104°
Record High: 114° (1933)
Average Low: 67°
Record Low: 57° (1916)
Average Precip: 0.004″
Record Precip: 0.18″ (1932)

It bothers me that we do not, in general, do a better job of teaching Science and Economics to our kids. No matter what career a kid eventually matriculates to an understanding of economics and science will always be helpful. I don’t think I ever had a teacher that was much good at teaching Economics, and I’ve taken a lot of Economics courses. Most non-Economics teachers I’ve had were woefully, tragically ignorant of the subject when it overlapped into their disciplines. I heard the head of all the public schools in New York City on television shouting about the evils of capitalism in an amazingly ignorant and uninformed way.

Garbage in, garbage out.

I was fine with that because I just liked being able to figure things out. I didn’t need to see how anything was relevant to get interested in a topic.

What I think I would do if I were to teach a physics class now, though, is to use Mythbusters and real-world examples of the concepts I’d want to teach.

Forget perfectly elastic collisions, no air resistance, spherical billiard balls and ideal springs. For example, show a tape of a skydiver plummeting to earth, have the students time his free-fall and come up with his speed when he pulls the ripcord. Yes, mention air resistance, but don’t set up problems that just can’t happen in the real world.