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The basis of known life on Earth is water, clear and simple. But what about forms of life on other worlds? Not every world in the universe is as hospitable as the Earth.

Suppose a planet had an average temperature slightly higher than the melting point of iron: 2,800° Fahrenheit (1,538° Celsius). On this world, there is roughly the same landmass-to-liquid ratio as Earth, except the liquid here is iron.

Ignoring the plausibility factor of life naturally appearing in such an environment, what would native flora and fauna look like? What adaptations might they have for existing in such an unearthly world?

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    $\begingroup$ What is the landmass made out of, then? $\endgroup$ – DaaaahWhoosh Jun 2 '15 at 15:11
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    $\begingroup$ @WhatRoughBeast And iron sinks in water. I'm not sure what your point is. $\endgroup$ – Frostfyre Jun 2 '15 at 17:21
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    $\begingroup$ And iron continents won't float on water. Tungsten continents won't float on iron, either. The question referred to "landmasses". $\endgroup$ – WhatRoughBeast Jun 2 '15 at 17:24
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    $\begingroup$ Yeah and rocks/earth doesn't float on water. The mantle will just have to be made up of something denser than iron or tungsten $\endgroup$ – Necessity Jun 2 '15 at 17:30
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    $\begingroup$ Mercury & liquid lead :) It would make for a very strange environment. Imagine a world around a post-supernova neutron star. Any survivors of the supernova would like be planets coalesced after the explosion. The environment would be metal rich in all metals, even post iron metals. It could make for some truly exotic alien worlds. $\endgroup$ – Jim2B Jun 2 '15 at 18:24
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Floating plants. Molten Iron is hot. When I think of all this molten iron and high temperature, it reminds me of hot air balloons.

Hot air rises. Consider a plant that bobs up and down on the heat generated by the surface of your world. It bobs because it opens and closes the bottom of itself. When it's up high, it fills itself with cold air. When it drops down, it releases this cold air around it so that the hot air underneath it will push it upwards. It will never touch the molten iron, but it's constantly provided with lift. It's likely to actually look a bit like an ball , or kind of like a spherical parachute (Actually, it's probably going to pulse like a lung too). It's able to take this lift, and stay safe from the molten iron, while being able to photosynthesize in the air.

Perhaps you want something bigger. What if these plants grew in clumps? Now you have cloud sized floating plants.

But what if we don't want to be in the air all the time? Is there any way it can survive on the land? Since we know the liquid is the melting point of iron, lets take the land to be of element x, with some melting point higher than iron. As noted in the comments of the question, the landmass is Tungsten. These plants would likely burn up instantly that close to the surface - unless they were made of something with a higher melting point, such as Carbon, or palladium. What if there were plants that self coated themselves with these elements? We're probably going to have to hand wave the internal cooling and nutrient transport systems, but lets say there's an element y in liquid form that doesn't boil at the planet's temperatures. They might be able to survive, although on a world described as such, photosynthesis is unlikely at the surface. Instead, they may turn to using geothermal energy..

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    $\begingroup$ Oceans of iron and clouds of plant? This planet is sounding more awesome every second. $\endgroup$ – DaaaahWhoosh Jun 2 '15 at 16:48
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The answer:
I don't know of any chemical system that can maintain the complexity necessary for life at the temperatures you cited (~1,600 C).

Alternatives:
However, a variety of scientists have considered what other chemical systems life might use to cope with different temperature regimes. This reference provides a list of those thoughts along with relevant temperature ranges and other notes of interest:

I reproduced a table from that site here: $$\begin{array}{c|c|} \text{Temp Range} & \text{Macromolecule in Solvent} \\ \hline \text{400° C to 500°? C} & \text{Fluorosilicones in Fluorosilicones} \\ \hline \text{113° C to 445° C } & \text{Fluorocarbons in molten Sulfur} \\ \hline \text{0° C to 100° C} & \text{Proteins in Water} \\ \hline \text{-77.7° C to -33.4° C} & \text{Proteins in Liquid Ammonia} \\ \hline \text{-183.6° C to -161.6° C} & \text{Lipids in Liquid Methane} \\ \hline \text{-253° C to -240° C} & \text{Lipids in Liquid Hydrogen} \\ \hline \end{array}$$

A matter of perspective:
To life evolved on a Methane world and using the lipid - liquid methane system, our (Earthly) life would look like a world of "molten rock" (aka water) and we would look like beings made of liquid rock.

To us, beings using the fluorosilicones in fluorosilicone chemical system would look like beings of molten rock too.

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  • $\begingroup$ I'm not entirely sure how this answers my question, since I mentioned ignoring the plausibility of life occurring. $\endgroup$ – Frostfyre Jun 2 '15 at 16:58
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    $\begingroup$ @Jim2B, it may not answer the OP's question, but the "A matter of perspective" part is golden. +1 and thanks. $\endgroup$ – Henry Taylor Jun 2 '15 at 17:29
  • $\begingroup$ I did comment on not knowing any plausible mechanism but the rest I provided as a basis for what forms the life might take. Completely different chemical systems would mean that "it's life Jim, but not as we know it!" It would be very very strange to us. $\endgroup$ – Jim2B Jun 2 '15 at 18:21
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    $\begingroup$ I think there's validity to this answer's approach. If there is no known physical way for life to exist at those temperatures, then the problem leaps away from what could work physically and enters the realm of what resonates with the readers. Sanderson's Laws begin to be more important than the natural laws. $\endgroup$ – Cort Ammon - Reinstate Monica Jun 2 '15 at 20:15
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Molten iron is probably far too hot for this to work (even computerized robotic beings would have their silicon brains melt), but perhaps if you restate the idea for a world of molten sulphur like Io in orbit around Jupiter. Sulphur melts at a much more modest 388.36 K ​(115.21 °C), so oceans of liquid sulphur could indeed exist on a world with the usual silicate mineral shell surrounding an iron core.

Sulphur is also an important ingredient in many biological systems, along with phosphates, so while a life form might not actually live in the sulphuric ocean, life forms might take advantage of the sulphur vapours or the constant rain of sulphur oxides in order to get the elemental sulphur needed to sustain biological processes. A moon like Io is also immersed in Jupiter's powerful magnetosphere, so the sulphur thrown into the atmosphere by volcanic eruptions (or sulphur vapours boiling out of the oceans) could become energized . Life might be powered by electrochemical reactions driven by the availability of ionized sulphur in the atmosphere, a weird sort of analogue to the sulphur driven creatures living by deep ocean thermal vents here on Earth.

Obviously, these creatures wold need some sort of "feeding" mechanism, perhaps feathery protrusions to collect charged sulphur ions to drive the electrical system, and a "ground" trailing behind or below to control or bleed off excessive charge. Electrical energy would be stored in the biological equivalent of a battery or capacitor. The ecosystem of such an electrical world would be very strange (predation wold consist of stealing or draining the charge from another creature). The creatures wold also have senses built around the massive electrical, magnetic and radiation fields of Jupiter (or the primary planet, if we are talking about an alien solar system), and live in an environment where "snow" is elemental sulphur condensing out of the atmosphere....

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For the planet to be that hot, 2800° fahrenheight, the planet would have to be rediculously close to the star that it is orbiting. A good example would be a 'hot jupiter'.

Due to its closeness to the star, the planet would be tidally locked, meaning that one half is allways facing the sun. This means that there is a drastic change in temperatures from one side of the planet to the other. While one side may be 1600° celsius, the other may only be 500° celsius. All of these properties create some crazy weather like winds that travels over the planets surface at thousands of miles per hour.

Though the weather on such a planet would be so harsh I doubt anything could live there, this puts the temperature of the dark side of the planet within the temperature range that life form of a Fluorosilicones chemical system (from jim2B answer) could "survive".

It is thought that on such planets that the auroras that only occur at the poles on earth would occur all over the planet, which would be an amazing sight. The clouds would be made up of things that seem ridicoulous to us like metal, silicate and rock. It possible that it could rain metal, glass and other things.

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  • $\begingroup$ The winds would appear to be an issue for the floating plants. Good points. $\endgroup$ – Josiah Mar 5 '16 at 23:03

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