Eli5: How does the core of the Earth (or any planets) not cool and still give off tons of heat energy? Where is this energy coming from?
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But they do cool. It just happens over billions of years. The heat the planets have come from their creation among the superhot stars and they are gradually losing it.
The do cool off though – we no longer have Komatiities being formed which can only occur under hotter inner planetary conditions like those of the earlier earth which was still hot from planetary accretion as well as more radioactive elements within the early mantle.
As time as gone on, many of these radioactive elements have depleted but there are still many others which keep the inner planet hot. But it’s certainly cooler than it once was.
The core of the Earth (or any other planet) is still hot because of the energy generated by the process of radioactive decay. This process involves unstable atoms breaking down and releasing energy in the form of heat.
But they do cool. It just happens over billions of years. The heat the planets have come from their creation among the superhot stars and they are gradually losing it.
As rest said, they cool off. Smaller planets cool off faster (still 100s of millions to billions of years).
That happened to Mars: core cooled, because of that magnetic field dissipated (no circling core to generate it), and that exposed surface of the planet to the Solar wind. It is assumed that is how Mars was stripped of water. Solar wind blew off atmosphere (no magnetic field to protect it), lowered pressure, water evaporated and subsequently was blown off as well.
It is stipulated that hot circling core and magnetic field due to that might be important for sustainability of the life on the planets. So smaller planets might not be good places long term as they cool off faster.
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I had also read that the pull of gravity by the moon and sun cyclically deforms the earth, creating internal friction that also contributes to added heating. Somebody more knowledgeable on the topic can expand on this.
The do cool off though – we no longer have Komatiities being formed which can only occur under hotter inner planetary conditions like those of the earlier earth which was still hot from planetary accretion as well as more radioactive elements within the early mantle.
As time as gone on, many of these radioactive elements have depleted but there are still many others which keep the inner planet hot. But it’s certainly cooler than it once was.
The core of the Earth (or any other planet) is still hot because of the energy generated by the process of radioactive decay. This process involves unstable atoms breaking down and releasing energy in the form of heat.
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