# 'Anything on Earth that can't be found in the rest o' the solar system? **URL:** \ **Category:** Factual Questions\ **Created:** [June 9, 2003, 12:09am UTC](https://boards.straightdope.com/t/anything-on-earth-that-cant-be-found-in-the-rest-o-the-solar-system/180545 "2003-06-09T00:09:19Z")\ **Posts on this page:** 6\ **Page:** 4
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [June 10, 2003, 4:37pm UTC](https://boards.straightdope.com/t/anything-on-earth-that-cant-be-found-in-the-rest-o-the-solar-system/180545/61 "2003-06-10T16:37:44Z")
Yes, the Thrints didn’t even invent space travel themselves. Some poor bastard explorers visited Thrintun and were instantly enslaved. Of course, this doesn’t explain exactly how the Slavers evolved telepathic mind control in the first place, given that there were no species on Thrintun that their mind control could work on. Hey, maybe HUMANS have irresistable mind control powers over sentient beings that don’t work on other humans. The first time the Vulcans or Cardassians land on Earth, BLAM! ---
**Author:** ![Yossarian](https://avatars.discourse-cdn.com/v4/letter/y/9de0a6/32.png) [@Yossarian](https://boards.straightdope.com/u/Yossarian)\ **Post date:** [June 11, 2003, 2:19am UTC](https://boards.straightdope.com/t/anything-on-earth-that-cant-be-found-in-the-rest-o-the-solar-system/180545/62 "2003-06-11T02:19:20Z")
> [@](#): > > \*Originally posted by Podkayne \* > \*\* > But, fractional crystallization and fluid immiscibility must happen everywhere there’s magma, no? What would make Earth (and if my reasoning is correct, every differentiated planet) unique is the particular profile of temperature and pressure conditions present in the interior, right? > > How does Earth differ from Venus, then, which has a similar size and composition (but, obviously, radically different geological processes)? > \*\* Re: the first paragraph, not necessarily. That a magma exists simply demonstrates that the first differentiation process, _partial melting_ (which is sorta the opposite of fractional crystallization (FC), has taken place. Once a melt forms, it may not differentiate further. If you partially melt a peridotite you will create a basaltic magma. The basalt may evolve a bit more via FC processes, but not enough to significantly concentrate any of our rarer (“incompatible”) trace-elements. Liquid Immiscibility doesn’t even kick in until later, and only then if there is enough of some liquid (a carbonate, sulfate, or aqueous phase) in the first place! I’d have more to say, but I’m freshly back from a successful fishing trip and MUST shower after I go clean my bounty! Perhaps tomorrow, if the thread still exists… ---
**Author:** ![CelraySoda](https://avatars.discourse-cdn.com/v4/letter/c/e36b37/32.png) [@CelraySoda](https://boards.straightdope.com/u/CelraySoda)\ **Post date:** [June 11, 2003, 4:59am UTC](https://boards.straightdope.com/t/anything-on-earth-that-cant-be-found-in-the-rest-o-the-solar-system/180545/63 "2003-06-11T04:59:11Z")
I’m sure that there is a race of strong armed aliens more useful for manual labor than us humans…we are too fragile, need to sleep and we require too much food/water/necessities, etc. That’s why the Draks were better in Alien Mine. All humor aside…if I had to name one thing that would be a point of interest to an Alien race to steal from Earth would be our ocean food supply to restock (that is if they are carbon based and need proteins and fats). That’s the best I can come up with…what do you think? -M ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [June 11, 2003, 12:08pm UTC](https://boards.straightdope.com/t/anything-on-earth-that-cant-be-found-in-the-rest-o-the-solar-system/180545/64 "2003-06-11T12:08:15Z")
Jeepers, it would be very unlikely that the alien race would be able to eat earth food easily… they could have entirely different metabolisms, different proteins, amino acids and enzymes, and even more likely they might have salts and trace element requirements or sensitivities that are either not met by our fish and other biota, or even render our biota poisonous to them. * * * SF worldbuilding at [http://www.orionsarm.com/main.html](http://www.orionsarm.com/main.html) ---
**Author:** ![Podkayne](https://avatars.discourse-cdn.com/v4/letter/p/edb3f5/32.png) [@Podkayne](https://boards.straightdope.com/u/Podkayne)\ **Post date:** [June 11, 2003, 12:58pm UTC](https://boards.straightdope.com/t/anything-on-earth-that-cant-be-found-in-the-rest-o-the-solar-system/180545/65 "2003-06-11T12:58:54Z")
> [@](#): > > \*Originally posted by eburacum45 \* > \*\*Volatiles are separated by heat = distance from the Sun, that is well known, but- > Do you suppose that the entire solar system might have worked as a diferentiation machine? > Mercury is extraordinarily dense, for it’s size- do you think there could be more heavy elements in the innermost planets, which could mean that each world really has something different to offer to the alien or indeed the human prospector? > \*\* You do find a greater fraction of lighter elements incorporated in planets the farther out you go in the Solar System, but not _because_ the elements are lighter, per se. The farther you get from the Sun, the more volatile compounds can exist as solids, and if you’re going to build planets, you need solid compounds. Now, volatile compounds, in practice, are made of lighter elements. The less volatile comounds (the refractories), which are solid even at high temperatures, could therefore be found solid _anywhere_ in the presolar nebula, and are therefore found in _all_ the planets. The reason that Mercury is so dense is that it lacks the more volatile compounds. So if you had a giant machine that ground up planets and allowed you to extract all the elements, and you were looking for heavy elements, you’d wan’t to go to Mercury because it has less “junk” (lighter elements) mixed in. However, a perhaps more interesting question is, does Mercury have heavy elements available in a useful form at its surface? Which is what I think **Pantellerite** is getting at. ---
**Author:** ![Yossarian](https://avatars.discourse-cdn.com/v4/letter/y/9de0a6/32.png) [@Yossarian](https://boards.straightdope.com/u/Yossarian)\ **Post date:** [June 12, 2003, 1:56pm UTC](https://boards.straightdope.com/t/anything-on-earth-that-cant-be-found-in-the-rest-o-the-solar-system/180545/66 "2003-06-12T13:56:14Z")
Exactly, **Podkayne**. Everything in the solar system has basically the same bulk composition (plus or minus certain volatiles): that of a carbonaceous chondrite meteorite. (Yes, even the sun, if you subtract H + He, has a chondritic composition!) The difference is what has happened since the planets and planetesimals initially accreted from the solar nebula (whose non-volatile composition is represented by the CC meteorites). Most apparently differentiated at least some during the first billion years or so of the solar system, creating planetary cores of Fe + Ni and a basaltic crust–but that’s about as far as they went. Only on Earth have these differentation process continued (driven by the plate tectonics) and even more evolved igneous rocks formed–evolved igneous rocks that contain _economic_ concentrations of rare elements that are incompatible with all common mineral phases. So, as far as bulk composition is concerned, yes all the solar system pretty much has everything. However, as far as DISTRIBUTION of these elements is concerned, with the probable exception of Fe + Ni (since planets and protoasteroid planetesimals did form a core), everywhere else most of the rarer elements are still disseminated and only on Earth do we find rocks (e.g., granite, pegmatite, carbonatite) where they have been concentrated. [Previous page](https://boards.straightdope.com/t/anything-on-earth-that-cant-be-found-in-the-rest-o-the-solar-system/180545.md?page=3)