Dan's Wild Wild Science Journal

NASA image

(Reminder that this blog is now part of the AGU Blogosphere at http://blogs.agu.org/wildwildscience/ Check them out!)

I’ve often wondered about something. Suppose a 1000 meter wide space rock  were to hit Nashville TN. Would I survive here in Huntsville in North Alabama?

It would depend on many factors of course. Nashville is about 165 km to my north. That’s a BIG factor.   The size of the asteroid, and the angle of impact, are others.

Let’s say that it hit at a 60 degree angle and was a rather dense mix of rock with some ice. The ground in Nashville is made up of sedimentary rock, so that will also be a factor.

What’s the answer?

Do I survive? Probably not.

The scenario I am about to give you is based on IMPACT EARTH. It’s a program put together by scientists at Purdue University and Imperial College in London. They have recently updated the physics and you can check it out yourself online here.

So what would I experience at a distance of 165 kilometers?

The rock would begin to break up at about 70 km above the surface. I assumed an initial speed of 25 km /second. It would be slowed only very slightly by our atmosphere and hit the surface traveling 24.7 km/ second. The fragments of the asteroid would hit the ground over a relatively small area. An ellipse of around 1000 meters to 1500 meters.

The crater formed would be 16 km wide! That is over 10 miles for metrically challenged Americans.

At the time of impact everything down to 4 km would be vaporized. The vaporized earth and buildings would fill the crater back in and it would only be around 700 meters deep at the end. Downtown Nashville would be gone before anyone there knew it. They might have a couple of seconds warning at most.

The blast in Nashville would produce the same energy as nearly 6,000 15 megaton hydrogen bombs detonated at once.

Let’s assume I’m outside walking the dog in Big Spring Park in the middle of  Huntsville. The flash in the sky as the rock hit the atmosphere would last only 2-4 seconds. It would be silent. No noise. The impact fireball would look 16 times larger than the sun.

If it’s sunny, walk outside and look up at the sun. Close your eyes and feel the warmth. The heat from the blast 165 km away would feel 27 times hotter than that. The heat would be instantaneous.

The Tunguska event in Siberia was from a much smaller space rock than we are talking about here. It leveled the forest for 200 miles around the impact.

I would suffer third degree burns and trees and grass around me will catch on fire. If I were inside when it hit, the burns would be less severe. Most of the city would still be alive.

It would still be quiet.

As I looked around in pain from the burns, I would see fires everywhere. People would be rushing outside to see what was happening.

33 seconds after the impact, Huntsville would feel an earthquake of magnitude 7.9.  Most well built buildings would not collapse but many people will be injured by falling objects. It would probably knock me off my feet in Big Spring Park.

The fireball in the northern sky would be huge but about 2 minutes later a black cloud would soon be visible. This black cloud would be made of gravel sized rocks and very fine dust. The ejecta cloud arrives in Huntsville 3 minutes after the impact. It’s now very dark with fires burning as the ground shakes.

Hell would rain down for 5 more minutes. It’s not over though.

What winds over 300 km/hr (200 mph) will do to a home. This image is from the aftermath of an EF3 tornado in Oklahoma. Courtesy NOAA/NWS

Eight minutes after the impact an explosion so loud it will cause excruciating ear pain will be heard. Almost immediately, a blast of wind will hit the city. Winds will increase briefly to over 90 meters per second. That’s over 200 mph.

Even strong buildings will likely collapse. Anyone outside will literally be blown away. Frame houses that were on fire seconds before will be blown away.

How about those who are further south? The winds in Birmingham would only reach hurricane force. The thermal blast would not cause burns. Heavy damage from the 7.9 magnitude quake would be likely.

Astronomers think that objects like I described hit Earth twice every million years. Objects big enough to destroy a large city hit Earth every 3 centuries on average. The Tunguska event in Siberia in 1908 was one of these.

The rock that wiped out the dinosaurs was 10 km wide. Those type events are thought to happen only once every 300 million years or so.

Just something to think about…

Dan

sources:

Impact Earth Calculator- http://www.purdue.edu/impactearth

http://impact.ese.ic.ac.uk/ImpactEffects/effects.pdf

http://www.gps.caltech.edu/~sue/TJA_LindhurstLabWebsite/ListPublications/Papers_pdf/Seismo_1747.pdf

Image form the Climate Prediction Center NOAA. Click to make BIG.

The strong and developing La Nina means that a decent long range forecast of the winter is possible. La Nina, and it’s cousin El Nino, tend to produce predictable weather patterns over the winter months.

Something to keep in mind. The forecast is for the average of the winter months. An above average temperature does not rule out some brief severe cold outbreaks. A drier than normal winter does not mean a certain region will not get a big snow storm.

Image from NOAA.

That said, here is what we can say with the La Nina. The South and Southeast USA will likely be warmer and drier than normal. The Tennessee and Ohio Valleys may see some heavy rains and floods.

Here in North Alabama we could go either way. We are right on the line. 65% of the time we have a milder than normal winter with a La Nina.

La Nina’s tend to bring cold and snowy winters to the NW corner of North America. If you live in Vancouver BC, watch out! It might be a winter to remember!

Kentucky and Ohio look likely to be cool but quite wet.

You can check out the maps but remember this is an average for the winter months!

I was on a conference call with some climate experts yesterday when someone mentioned this graph from NOAA. Every decade from the 1950′s through 2000-2010 was warmer than the decade before it.

Every decade since 1950 has been warmer than the one before it. Click image for higher resolution.

NOAA also has released the September temperature anomalies. Even with the strong La Nina of cool waters in the Pacific, it was the 8th warmest on record. January through September is now tied for the warmest year on record as well.

Red dots are warmer than normal and blue dots are cooler than normal. The string of blue in the Pacific is the strong La Nina developing.

If someone tells you this is being caused by the sun, you can reply that the sun has been unusually quiet this year. It only recently began to get active as the next solar cycle starts.

The graph of the decadal temperatures smooths out the natural cycles like El Nino and the Pacific Decadal Oscillation. It also smooths out the slight rise and fall in the global temperatures from the solar cycle.

Oh, there is this:

It’s called the Keeling Curve in honor of Charles Keeling who started the carbon dioxide measurements at Mauna Loa. The reason 97.5%* of climate scientists are sure the planet is warming, and that it’s the greenhouse gases that are doing it is simply this.

Every other realistic possibility has been ruled out. Yes, there are natural cycles but the greenhouse gases will warm the Earth no matter

As Neil DeGrasse Tyson says: The laws of physics are real. Everything else is just politics.

* That number is based on peer reviewed science

The Royal Society was once presided over by Isaac Newton himself. It’s the world’s oldest science institution.

They have just released a very good summary of what is now known about climate science and climate change.

Well worth a read.

Speaking of science, this blog will soon be part of a new project by the American Geophysical Union. The AGU has over 50,000 members worldwide and is one of the largest science organizations on the planet.

The AGU will soon be hosting a collection of earth and space science blogs. I was honored to be asked to join in!

This means you will soon see a different look here! Even better, you will be able to quickly read the thoughts of other people who are as fascinated about the world around us as I am!

More soon,

Dan

Unlike the UK, where a TV and Radio license  fee pays for the BBC’s slew of excellent educational programming, we have only NPR and PBS here in America. I’ve frequently compared NPR to the BBC with no money. That really about covers it….except.

NPR is still fabulous.

If you see Wonders of The Solar System on in your area, then make plans to watch it. This BBC program is full of fabulous science. (image from the BBC)

In an era where scientific ignorance seems to be at it’s peak, we have very few excellent programs on Science available. Yes, NOVA and NATURE are great. Hopefully the BBC series Wonders of The Solar System by Astronomer Brian Cox will make it here soon as well.

Some of the programming I’ve seen on the History channel and Discovery are absolute junk. Especially the 2012 stuff. In reality there is a slew of junk science programs on backwater cable. Trust me, if it’s about UFO’s, aliens from space helping to build the pyramids, or Nostradamus, then you are being sold a bag of fertilizer.

Discovery does get a kudo from me, and that is for Astronomer Phil Plait’s Bad Universe. Science is, and can be shown to be, rabidly interesting and Phil Plait makes it so.

Before you think that nobody takes those programs seriously, let me tell you something. I was getting a danish in the Albany airport, when the girl behind the counter found out I was a meteorologist. Guess what she asked me?

What is the dew point? Will it rain tomorrow? What does 40% chance of rain (answered here) really mean?

Nope.

The actual Question: “Is the world really going to end in 2012???”

My answer: “Trust me, it’s not.” I wanted to add “you should cancel cable.”

Consider, that hundreds of thousands of gullible folks are buying bracelets that harness magic fields that do not exist. Add in the school boards who are trying to ban science books based on solid  science because they are politically unpopular, and you know we truly have a problem.

American students rank with 3rd world countries now in math and science. I’m not exaggerating. A Canadian high school graduate has more science and math knowledge than many college seniors in America.

Now, comes news that Science Friday on NPR has lost some of it’s funding. I rate that program the best regular science program on radio (U.S. at least). Good solid science that is fascinating and timely.

It turns out that if you make a donation this year to the program they have grant that will match it two to one! The word that their funding might be in trouble has already gotten them an outpouring of support. You can find out more about how you can help here. You can listen to today’s (Friday Oct 8th 2010) program here.

Trust me, they will get a donation from me!

So will my local NPR station that carries the program.