Geology in the Movies: The Chronicles of Riddick

Published 2008-03-21 by Chris

The 7th edition of The Accretionary Wedge geoblog carnival has the theme of “Geology/ists in the Movies”. I found the temptation to tackle a movie like The Core (a part of which I looked at in AW 5) truly palpable. Other geo-movie triumphs such as Volcano, Dante’s Peak or Journey to the Center of the Earth were also high on the list. But when I got down to it, I remembered a movie I saw during the second year of my BSc, a part of which struck a chord.

During The Chronicles of Riddick, the petroleum-inspired Vin Deisel’s sequel to Pitch Black, the story concentrates on a planet called Crematroia. So extreme are the conditions on this planet that I couldn’t pass up the opportunity to give it a once over with a geological eye.

To Vin’s credit, the movie is specific with its measurements including temperature, and the metric system seems to prevail (Vin’s character talks of grams and kilometres). The Crematoria field trip involves breaking the basic laws of physics. But if you can overlook that little problem and ignore heat dissipation as a naturally occurring phenomena there’s some alright, extreme geology to be had.

Figures

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Crematoria – The Conditions

The portrayed gravity and atmospheric conditions require Crematoria to be an Earth-sized planet. The extreme temperatures of 700°C (973 K) on the day side and  -300°C (-26 K, below absolute zero) on the dark side, would require an orbital distance from its star (assumed by me to be sun-like), closer than that of Mercury’s (0.30 – 0.47 AU). That’s a diurnal temperature variation of 1000 degrees with a change of 200 – 700 degrees observed to occur over several seconds. That’s a hell of a lot of energy loss during the short (~3 hour) night.

In the movie the planet’s surface is dark, black, volcanic-looking rock, which bears a striking resemblance to your common basalt. Andesite would be possible, but not common given the slim change of crustal stability and the lack of plate tectonics causing hydration-melting of subducted slabs (and generating andesitic melts).

With Vin Diesel and other characters running over the jagged surface without breathing gear, it’s also a planet I’ll presume to have ~1 atm of atmospheric pressure, which undoubtably contains Oxygen, Nitrogen and other terrestrial gases (how could they breathe otherwise? Magic!?)

The Physics

I’m not a thermal physicist, but from what I understand, dropping 1000 K over the course of a few hours seems rather unlikely, especially when the lowest temperature is below absolute zero (this is, of course, impossible). A temperature drop of that magnitude in a heat-retentive atmosphere like the Earth’s is simply not going to happen. Case-in-point, last night, here at 41° South, the temperature fell to 14°C from 22°C during the day. And that was from ~8 hours facing and radiating heat into the cold, dark abyss of space. But let’s just assume for the case of the geology (won’t somebody please think of the rocks?), that all of this atmospheric physics is given a pass and we instead take a look at the rocks on the surface.

The Good Geology

Magma lakes would definitely be a feature on the surface (Fig. 5). Some basaltic magmas have been measured at temperatures as low as 750°C (in lava lake of Kilauea, Hawai’i)[1]. That’s a little above the maximum temperature cited in the movie with 700°C being the temperautre at the top of the volcanic clouds, rather than the bottom of the columns. The thermometer seen in the movie (Fig. 1) has a maximum reading of 700, so the temperature on the actual surface could be anything. You’d also get radioactive heating on a planet of that size, as well as an accumulation of heat energy and conversion of kinetic energy from the planet-consuming pyroclastic flows seen erupting along the planet’s terminator (Fig. 3 & 7). With that kind of heat energy, it’s a surprise the surface of the planet isn’t a magma ocean, but then again, that’d ruin the action sequences.

Speaking of those pyroclastic flows, I was delighted to see ash falling on the movie’s protagonists as they scurry across the surface during the night (Fig. 2). That kind of extreme temperature change probably would cause explosive surface volcanism, especially if there’s water and other volatiles around (as you get with a terrestrial atmosphere). Millions of cubic kilometres of ash would have to fall during the impossibly cool night, which is odd,considering most of the cooled material seen is not covered in white ash.

And on the topic of pure metals, when a space ship is exposed to the direct heat of the star, its metal partially melts (Fig. 8). Pure Aluminium has a melting point of 660°C, Titanium melts at a more hardy 1668°C, so it’d probably be a good idea for the bounty hunters who own the ship to re-plate it at some point.

The Bad Geology

This is a hell-like planet. It puts the conditions thought to have been common during the Hadean or on Venus (average temperature of ~460°C) to shame. However, despite the erosive power of planet-wide explosive volcanism occurring every 3 hours, jagged rocky outcrops and cliffs appear on the surface (Fig. 3, 4 & 5). Given that the gentle pitter pattern of rain over a few million years will eventually erode the Himalayas flat as they did to their predecessors [2], high, columnar basalt cliffs and wild jagged features are not likely to survive the erosive power of a massive volcanic explosion every 3 hours.

Despite their best efforts (to reasonably good effect), and ignoring the physics problems, Crematroia would be flat and covered in metres-deep ash deposits in the places it wasn’t a magma ocean.

References

1. http://www.minsocam.org/MSA/collectors_corner/arc/tempmagmas.htm
2. http://www.sciencedaily.com/releases/2003/10/031006071157.htm

All images used in this article, including the splash image on the front page/archives are © 2004 Universal Pictures.

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