Friday, July 23, 2010

Geological Movie Review of Armageddon - Part 2

Geological Movie Review of Amageddon - Overview

- Meteor Shower -


- Shuttle Impact -
0:03:19 - The first scene, following the background info, starts off with a space shuttle and a satellite being pummeled by tiny meteors ranging in size from golf balls to, I would say about television sets. In real life, could this really happen? That a meteor shower could take out a shuttle and a satellite?

First we must describe a meteor shower. A meteor shower is typically produced when the Earth passes through the tail of a comet. The millions of tiny particles in the comet's tail fly into the atmosphere producing the effect seen on the ground (CNN.com). Since these objects are moving at tremendous rates of speed (up to 30,000 mph) even grain sizes meteor could produce devastating damage were it to hit a satellite or a shuttle (Space.com). Most meteor showers are predictable though, since we know when we will pass through a comet's tail. Knowing that, we can prevent such damage from occurring. But if a meteor shower was to hit the shuttle and a satellite, then yes it could take out the shuttle, especially with baseball sizes meteors.

But this meteor shower did not originate from the tail of a comet, the meteors were part of an asteroid. I did say that meteor showers were typically produced by comet debris but it is possible, and has happened in the past, that larger meteors were pieces broken off of asteroids and even planets (Space.com). So if another object were to hit an asteroid, it could be possible that the debris caused by the impact would stray into the Earth's orbit. And since these are broken chunks of asteroid, it is also possible that they could be significantly larger than the comet produced meteors. So far, everything about this meteor shower is possible. The main question now is, is it possible that noone would detect this before it could happen? I will get into that in a little bit.

Now in the movie, when the meteors hit the shuttle they produced a similar fire trail effect as is visible on Earth when they are traveling through the atmosphere. How high up does this fire trail effect originate and would it occur around the shuttle? When meteors travel into the atmosphere they start to burn at an altitude of 80 miles down through 50 miles (SpaceWeather). Geosynchronous satellites, satellites that remain in a fixed location above the Earth, must remain in orbit about 22,000 miles above the Earth's surface while some satellites do orbit down to an altitude of 435 miles, but these are mainly polar satellites with a small coverage area (UCAR.edu). So even if the shuttle crew was working on the lowest possible satellite up in space the meteors still would not produce the fire trail associated with shooting stars. So this visual aspect is used just for a "wow" effect and is not based on any real science.

- Meteor Landfall -

0:06:51 - When the meteors reach the inner atmosphere they proceed to destroy New York City. Now since we have already determined that the size of the meteors are possible due to an asteroid impact, we now focus on the amount of damage that was caused.

The amount of damage caused in space and the amount of damage caused on the Earth's surface is dramatically different because the speed of a meteor within the atmosphere is cut down due to friction. When they enter the atmosphere, meteors produce an effect called ram pressure where they compact the atmosphere in front of them producing a fire trail that burns them up as they descend. Even though the meteors are slowed down they still can hit the Earth with tremendous force, so the amount of damage produced in NYC in the movie would not be hard to imagine. In the movie, the meteors are slowed down not just by ram pressure but also by buildings, streets, and people which help reduce the amount of damage on the ground. This would explain why the impact sites do not resemble Meteor Crater. Also, most meteors up to and including baseball size burn up in the atmosphere before they hit the ground, explaining why the meteors from the shuttle accident did not cause the mass panic that the later meteors caused (Space.com). This means that following the shuttle accident there was at least one more wave of larger meteors.

The main thing about the meteor shower that does not seem possible to me is the fact that according to the movie, meteors were splashing down from Finland down to South Carolina with apparently the vast majority of them hitting NYC (pictured left). Since the 3 locations can be connected with a straight line we might be able to make this work. To explain how meteors would hit the Earth you have to imagine that essentially the source of the meteors are a fixed point in space since they are formed far away. This is similar to the perspective of train tracks merging towards the horizon, causing individual meteors to appear to strike across the sky in parallel lines (CBC).

So every meteor that travels across the sky should be parallel to one another. Not so in the movie. Starting off with the first meteor that touches down, this meteor shower is inconsistent. The first meteor in the movie drops straight down on the Godzilla guy, while almost every other meteor comes in at an angle to the buildings. And not all of them even come in at the same angle, which is rare that some meteors would be diverted one way while others are diverted another way. It is possible, though, that meteors can travel in different directions during the same meteor shower but they usually have a different origin (Astropix).

Now onto the fact that the meteors are hitting from South Carolina through NYC to Finland. Due to the curvature of the Earth I would not anticipate that this would be possible unless they formed a stream, or a string, hitting the Earth. If they were to form a stream with the upper part of the stream reaching down to South Carolina (SC) and the bottom part of the stream hitting Finland then this could be possible (Green Arrow). Unfortunately one of the views the showed the meteors coming in at an angle indicated they were angled North, up the Manhattan island (Yellow Arrow). So for both scenarios to be possible then the meteor shower had to have been a flat sheet with the entire length hitting the Earth at the same time. Again this would have been possible if you consider the meteors as a stream across the sky and the Earth traveling into their path. Unfortunately this is not possible because the main asteroid is part of the stream and if the Earth passed through the stream then the main asteroid would pass by after the Earth went through the asteroid stream, not be headed directly for us.

In conclusion for this section I would say that the intent for the meteor shower was probably the Green Arrow because that is at least plausible and that the problem with the meteor angles was just for dramatic effect. The fact that the meteors come in ever increasing size pulses seems improbable. They most likely would come in by way of a continuous stream with a mixture of different sizes based on their formation, but I will go into that in a little more detail below. And I'm not even going to mention the amount of meteors that hit NYC because there is nothing to compare it to, since they did not even show any of the other localities that were hit.

0:56:23 - This is the random Chinese strike about halfway through the movie. Back in 1998 this part about the warning system would have been correct, but luckily (?) the 2004 Sumatra tsunami happened and caused the update/production of the tsunami warning system where 11 minutes is actually the amount of warning time they can be prepared for. Still a little short notice but at least it is something for the surrounding regions to get away from the water.

1:59:50 - The asteroid that strikes Paris is actually the most accurate meteorite impact that I have found in the entire movie.

Tuesday, July 20, 2010

Geological Movie Review of Armageddon - Part 1

This article is an update of an article I wrote for my website. The links and grammar have been updated and I soon hope to have the entire article updated on the website but for now this is the only location.

Disclaimer

This is going to be a geological overview of the movie Armageddon. I am not going to focus on the plot, the acting, the directing or anything of the sort. This is purely a scientific critique on the movie and one from my own mind, so do not take that into effect on whether or not you are going to like this movie. In "science fiction" movies the role of the science advisors are often outranked by the director or other people in the movie and the science gets left out. This means that the bad science of the movie is often not a result of a bad advisor. So do not take my critique of the science as a direct shot at the advisor.

Most geological movies make an attempt at merging bad science and a poor plotline to make an overall pretty bad movie. The geology in this movie seemed mostly just a veil for an interesting storyline. Now I know most people had problems with this movie but I enjoyed it, although the science was "slightly" flawed. Now on to the geological review. I will also make time notes for what part of the movie that part of the commentary below is referring to.

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- Geological Critique -


- The Story Basis -


The story's premise is that an asteroid hit the Earth 65 million years ago causing the extinction of the dinosaurs and that it is going to happen again. The plotline revolves around what would our society do today faced with a similar situation. How could modern technology save us? Or could it?


- Millions of Years Ago -


- The Earth -

0:00:37 - The first sequence gives the background of the movie. The premise is that an asteroid hit the Earth 65 million years ago (mya) causing the extinction of the dinosaurs and that a similar even will happen again, perhaps causing our (the human race) extinction. When the intro begins, the first sentence starts describing that the view seen was the earth as it was 65 mya. According to the voiceover the planet was lush and fertile. Scientific information that we currently have indicates that this is true. So far, so good. The only problem is that the view shown is how the Earth looks today, not how it looked 65 mya. A significant amount time has passed
since that event took place and the continents were in different locations compared to where they are today.


The map to the right is an interpretation of what the geography would have looked like based on scientific research. A bit different then the map seen in the movie (Scotese.com). Mostly you can see the area around the Gulf of Mexico is not the perfect gulf that is envisioned in the movie and South America was not as close to the impact point as it is today. The dot indicates the location of the impact site and in the movie it is in the exact same location, the Yucatán Peninsula. So at least that was accurate.


- The Asteroid and the Impact -


0:01:04 - The asteroid in the movie is described as a piece of rock 6 miles wide. First off to interpret the movie asteroid, we need a few definitions of some extraterrestrial materials:


Asteroid - any of numerous small celestial bodies composed of rock and metal, 480 miles (775 km) to less than one mile (1.6 km) in diameter, that move around the sun (mainly between the orbits of Mars and Jupiter). Also called minor planet, planetoid. (dictionary.com)


Meteoroid - A solid body, moving in space, that is smaller than an asteroid and at least as large as a speck of dust. (dictionary.com)


Meteor - any of the small solid extraterrestrial bodies that hits the earth's atmosphere. (dictionary.com)


Meteorite - a mass of stone or metal that has reached the earth from outer space; a fallen meteoroid. (dictionary.com)


Comet - An object that enters the inner solar system, typically in a very elongated orbit around the sun. Comets are thought to consist chiefly of ammonia, methane, carbon dioxide, and water, or ice. (dictionary.com)

So based on the definitions, a 6 mile wide rock would in fact be an asteroid and it is not an unusual sight in the solar system. This is what actually is thought to have hit the Yucatán Peninsula 65 mya. So far, in general, the movie is pretty accurate.

The movie then goes on to state that the rock hit with the force of 10,000 nuclear weapons. To understand this you must understand that most objects in space are moving at a tremendous rate of speed compared with the Earth. When asteroids hit the Earth they are typically moving about 6 to 12 miles/sec, so even a small one will produce a big dent. The crater to the left, Meteor Crater in Arizona, was formed by a meteorite 150 feet across, or about 0.5% the size of the Yucatán asteroid. The explosive force produce during the Meteor Crater impact is considered to be about 2.5 megatons, or about 150 Hiroshima bombs, and produced a crater a mile wide (barringercrater.com).

The Chicxulub crater that was created from the Yucatan asteroid is 110 miles across and the estimates for the power resulting from the impact vary widely. They range from 100 million megatons (universetoday.com) up to a trillion megatons (oregonstate.edu). That is a very wide range of possibilities so one must take the high extreme with a grain of salt, since the majority of sources that I found quote the 100 million megatons, or somewhere within the ball park of that. So that is likely the best current estimate for the amount of power released during the impact.

The movie also compares the Yucatán impact to the explosion of 10,000 nuclear weapons. But when comparing them, do you compare it to the Hiroshima bomb or to the much larger modern day nuclear weapons? In comparison to the Hiroshima bomb, 10,000 nuclear explosions would be about 167 megatons. Far, far smaller than our current estimate of 100 million megatons.

Currently, most nuclear bombs that are made are less than 1 megaton, although a megaton bomb is easily possible (nukefix.org). So we will consider in the current day values that the Yucatán asteroid struck with a force of 100 million megatons. Still far less than the trillion megatons, but we will assume that is a wild card anyway. The largest nuclear weapon ever created was the Tsar Bomba (pictured right), which was designed to have a yield of about 100 megatons (nuclearweaponarchive.com). Using this bomb as a basis we would have an impact that would be about a million megatons (100 megatons times 10,000 nuclear weapons). Still, only 1% of the modern day estimate of 100 million megatons.

The range that we could produce with the movie statement shows that comparing something to a value such as nuclear weapon strength is a poor method of describing anything, since nuclear weapon strength is very variable. The most conservative measure of the asteroids impact strength of 100 million megatons seems the most accurate. By comparing this to 10,000 Tsar Bomba nuclear weapons, we would have our closest estimate to the size of the impact, which is still only 1% of the total actual strength. So, I feel that the directors were likely going for a much smaller impact strength when coming up with these number because otherwise they are not even close.


- Dust Cloud -

0:01:25 - When an asteroid this large strikes the Earth it is bound to send up a debris cloud far into the upper atmosphere (pictured left). When it is in the upper atmosphere, air currents quickly carry the dust cloud around the Earth, essentially
blanketing the Earth. According to the movie a trillion tons of rock and debris were sent into the atmosphere where it blocked out the sun for a 1,000 years. Although the amount of debris that an asteroid can produce is up for speculation, a trillion tons of debris compared to the size of the Earth in general is miniscule.

Now the blocking of the sun for a 1,000 years is probably a vast overestimate. Most estimates place the amount of time that the debris "blocked out the sun" as several weeks to months (webspinners.com). When debris is put into the atmosphere a majority of it is too heavy to remain air born so it falls out fairly quickly, whether it be within months or years. When the thick debris has fallen out the finer ash and dust particles can remain in the atmosphere for years or even decades (atmos-chem-phys.org), but the remaining finer dust would not block out the sun. So the over-estimate of 1,000 years is a tad dramatic.


What is interesting is that in the debris cloud is shown as a fire ball that envelops the Earth. Although not mentioned verbally, this is an important aspect into the science of an asteroid impact. After the impact, the debris that falls back to the surface would create a storm of rocky fireballs and the surface would be brought to a boiling temperature incinerating everything near the impact site (telegraph.co.uk). So the fact that there is a fireball wave that extends outward from the crater is accurate, how far it goes from the impact site is another matter.


The main problem is how far is the affected area. It is hard to tell in the movie but it appears that the fireball extends across at least a quarter of the Earth's surface. There are two types of fire clouds that emerge from the impact, a warm fireball and a hot fireball (diagram to the right). The warm fireball travels across the surface of the Earth for 100's of miles while the second fireball, the hot fireball travels further up in the atmosphere for 100's to possible 1,000s of miles. So could the fireball act like it did in the movie? It is possible. It mostly depends on how far it actually traveled. More than likely though, the movie overly exaggerated the dstance, but not by much I would say (plattsburgh.edu).


- Again? -


0:01:46 - "It has happened before, It will happen again." Definitely. Back early in Earth's history the planet was pummeled with meteors causing it to look similar to the moon. This is due mainly to the majority of debris left over from the formation of the solar system. Plate tectonics and active volcanism has a tendency to erase the evidence of the past so the Earth does not look as it did back then. Most of the asteroids and meteors that have hit the Earth since were from the partial formation of a planet between Mars and Jupiter, which got ripped apart by the gravity of Jupiter and is now just the asteroid belt. When the belt was fresh there was more debris to hit the Earth but since most of the rogue debris has crashed onto planets, there is not much left. Although there is a lot of asteroids still hanging out there and several chunks do pass close to Earth's orbit. It is only a matter of time until one of them hits us.

Wednesday, July 07, 2010

Science selling out?


So an interesting thing is happening over at ScienceBlogs today. It turns out that the overlords of ScienceBlogs have invited Pepsi in to contribute to their own blog. Granted this by scientists in the Pepsi family but it is far from impartial. Which is what science is supposed to be.


So it seems that many of the bloggers over there have taken a bit of a hiatus to see how things come out. The background of ScienceBlogs is that they invite blogging scientists to contribute on their site. And from the blogs I have seen over there it is some of the best content on the web (including Eruptions and Highly Allochthonous, among others). So it will be interesting to see how this turns out.


It is a shame that I don't have more time to blog now otherwise I could probably pick up more readers from the disenfranchised ScienceBlog readers (since I am not one of the privileged few to be invited). Oh well...