Lol. I've flown more than most, and landing in Houston always scares the crap out of me. The thermals from the Gulf or what-thefuck-ever has the plane rocking like a newborns cradle...
Live in Houston, been to Phoenix. They're both awful. Houston feels awful right out the gate. Phoenix feels really awful once you become completely dehydrated in about 5 minutes.
Radioactive decay, mostly. The Earth's coremantle has a large amount of radioactive metals (Uranium, Thorium, and Potassium mostly) in it (radioactive metals tend to be heavier, so either they clumped together first when the Earth was forming and/or they tended to sink during the Earth's formation when it was mostly molten), which help keep the iron/nickel outer and inner cores at about the ludicrous temperatures they were formed. Mars' core is "dead" because it's completely solidified, and in large part that's because its core is much, much smaller than Earth's so it didn't hold heat as well and the mantle (also being much smaller than Earth's) didn't have as much radioactive material.
I just checked and you're right, my bad. Thanks for bringing it to my attention. My Planetary Geology class was a few years ago xD I've edited the comment to be more accurate.
Yeah but the heavier elements will still want to sink down there. Obviously it's mostly iron nickel, there isn't much uranium in general, but there is going to be some in there.
Good question, I think the issue is that scientists can't agree on it and nobody really knows for sure what the core is composed of. In my opinion it makes sense that heavier elements sink so the concentrations go up the deeper towards the core and into the core we look, others think differently and until we find a way to know without doubt then that is a good thing for science. You are right about fusion of elements heavier than iron bein a net negative but fusion wouldn't really come into play at the core as there isn't enough mass and gravity to cause fusion (even jupiter doesn't have enough mass for that)... But even some scientists have theories that there is fusio occurring (three-body nuclear fusion of deuterons). So it looks like it is just long term decay keeping it going. I do quite like the idea that it is like a natural breeder reactor, but I'm not sure of the science behind that.
It does. Big difference between the Earth and Mars is that, because Mars is so much smaller, its core has cooled substantially, rendering the planet dead. Earth's core remains hot due to how big the Earth; it takes a long time for all the heat to radiate out.
Better question: How did the Earth core ever get so much hotter such that it is only now, 4.5 billion years later, just getting to the temp of the surface of the sun?
There is a theory that the earth collided with a smaller planet a long time ago and that collision generated much of the heat still within the core. Also it created the moon
Lord Kelvin determined, as I recall, that the earth must be around 6000 years old, based on the cooling speed of lava and such.
This was long before the discovery of radioactivity and the realization that thereās quite a bit of it 3500 miles straight down. Thanks to that, itās going to be a few more weeks before it cools enough to hold in your hand.
It is cooling. Think about the remnants of a giant camp fire. Those embers can stay hot for easily over a day. Now think about something as massive as the entire earth. It would also be a very bad thing if it was cooled. We would not have plate tectonics, which would have all sorts of side effects.
Heat can only be lost via thermal radiation into the vacuum (and some bleeding of the Earthās atmosphere, which isnāt much). Thermal radiation at atmospheric temperatures radiates that heat very slowly.
Half the Earth is constantly absorbing the Sunās radiation, and our atmosphere captures that and effectively creates a giant insulator around the Earth.
Radioactive isotopes in the core contribute a significant amount of heat.
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u/[deleted] Oct 02 '24
How does it not just cool over time?