Krypton's core is made of uranium? (mathy types wanted)

[JulianPerez]

One of the more interesting and so-very fifties science fiction ideas that was introduced during the Weisenger years was the idea that the reason Krypton exploded was that Krypton's core was made of uranium - and as a result of a chain reaction, the core exploded, turning Krypton into a gigantic atomic bomb.

Most later sources were vague about the hows of Krypton's destruction under Schwartz's tenure (and let's not even mention the clueless Black Zero story Carlin and his bootlickers inflicted on us).

But this fact might be interesting to use to speculate on what sort of planet Krypton was like.

DISCLAIMER: I'm not a scientist by trade, just an amateur making guesses.

For one thing, it means that it's possible Krypton might not be as large as we believe; uranium is a very dense metal. It's density is about 19.1 g/cm3.  Water, in comparison, is 1.0 g/cm3.

The average density of the earth is 5.5 g/cm3, making it the densest planet in the solar system. It's interesting to note that the density of most metals found in a planet is on average, about more or less 8.0 g/cm3 and the density of rock is (more or less) 3.0 g/cm3. Taking that the earth is part rock and part iron, the average of the rock and metal divided together is 5.5, the density of the earth.

(The average density of Saturn is .7 g/cm3, less than 1.0 g/cm3 of water - meaning Saturn could float in water - if you had a big enough bathtub.)

Using that same way of figuring out planetary density, we get a Krypton, part uranium, part rock, that is 11.05 g/cm3 - nearly twice the density of earth. Using this - and Captain Kal's 35 G figure, what would the volume, diameter, and circumference of Krypton have to be?

What would be some of the problems of a planet with a uranium core? Well, obviously the radiation; it might be interesting to account for why life on Krypton was allowed to exist and evolve at all.

The second is the fact that without a magnetic element (like iron or nickel) to form the liquid core, the planet has no magnetic field to protect it from cosmic radiation. This does not necessarily mean that the planet has no magnetic field; some gas giants in our solar system have magnetic fields, but have no core as a result of the unusual properties of some gases. This may account for Superman's phrase in many Kandor stories that "encounter with Krypton's atmosphere reduces my powers."

(Incidentally, I only recently found out that uranium was actually pale and silvery. Interesting - in comics and movies and so on, Uranium is usually drawn as yellowish or copper-colored.)

[Super Monkey]

Actually Earth might be one of those planets as it turns out:

http://www.newscientist.com/article.ns?id=mg18725103.700

[dto]

Refined uranium is a pale silvery metal, but in its natural form when mined uranium oxide is yellow.  During the refining process, uranium concentrate is called "yellowcake" due to its color (70-90% uranium oxide).

[MatterEaterLad]

The idea of a core composed of Uranium is a little far fetched even if it is fun...probably present in small amounts throughout the universe's matter, it is simply uncommon...hugely dense, massive nucleus, and because of that mass why it can generate such energy (as Einstein suggested), a core of Uranium seems outside the realm of any normal planet's development...and its stability over any period of time...

[ShinDangaioh]

Any normal planet.  Krypton was not a normal planet.

Its origin is here on the site.  It was created by a group of beings that live inside Rao(The Kryptonian sun) to stablize the sun's energy.  Throw out any idea of natural planetary devlopment.  Krypton is not going to follow the rules of other planets

[MatterEaterLad]

Krypton is a more fun planet without convoluted and tortured attempts to make it scientific...and any attempts make it even more ludicrous...

They are comics after all...

[Brainiac44]

Hi,

Remember Superman the movie?  Krypton's gravity was shifting (from memory)...  If we looked through a few comics that have Superman's origin repeated, we'll find a few other reasons why Krypton has exploded.  Once we find out (for example) that a planet cannot explode no matter what sort of core, then Superman will have another origin.  The main thing is that "Krypton exploded" - am I bad or am I bad?

[Captain Kal]

Excellent thread topic per usual, Julian.

Quick comments since I don't have time for an indepth analysis at work right now ...

More massive planets are more likely to retain higher proportions of heavy elements.  Uranium certainly qualifies.

Natural uranium is mostly the U-238 isotope which is not fissionable so it's unlikely to be an instant nuclear bomb.  However, the small proportion of fissile U-235 in a planetary core made of the stuff plus the fact that the core is probably not pure uranium but a mixture of elements like our own might give us the equivalent of a planetary nuclear reactor that later ran out of control.  Perhaps the proportion of U-238 gradually transmuted to plutonium like in a breeder reactor and the mass became critical in Jor-El's time.

FYI, our own planetary core is rendered molten hot partly due to trapped heat from planetary formation billions of years ago but mostly due to heat of radioactive decay.

Our magnetic field is due to electric currents in the planetary molten core which would still be generated in a molten core largely made of uranium.  It is not mandatory for iron or nickel to be present to generate Earth's magnetic field just moving core currents.  For comparison, the sun is largely hydrogen and helium yet it has a magnetic field that dwarfs Earth's.  The sun certainly has those vast moving currents needed for a magnetic field.