Earth's core remains incredibly hot due to a combination of factors: the lingering heat from its formation, the ongoing decay of radioactive elements within it, and the heat generated by the solidification of the liquid outer core.
Sources of Earth's Core Heat
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Leftover Heat from Planetary Formation: The Earth formed from the accretion of dust and gas approximately 4.5 billion years ago. This process released immense gravitational energy, converting it into heat. This initial heat is slowly dissipating but continues to contribute to the core's high temperature. As stated by multiple sources, this initial heat is a major contributing factor. (See references from
reddit.com,scientificamerican.com,quora.com, andearthobservatory.sg) -
Radioactive Decay: Radioactive elements, such as uranium, thorium, and potassium, are present within the Earth's core. Their radioactive decay releases heat continuously, acting as an internal heat source. This is highlighted in many of the references including
physics.stackexchange.com,reddit.com, andpsu.edu. -
Latent Heat of Solidification: The liquid outer core is gradually solidifying near its boundary with the solid inner core. This process releases latent heat, further contributing to the core's high temperature. This is mentioned in resources like
psu.edu.
The Inner and Outer Core
It's important to note that Earth possesses both a liquid outer core and a solid inner core. The immense pressure within the inner core prevents it from melting despite its high temperature. (See theconversation.com) The liquid outer core, composed largely of molten iron, is the source of Earth's magnetic field. (See scientificamerican.com)
Conclusion
The Earth's core remains hot due to a combination of residual heat from its formation, ongoing radioactive decay, and the latent heat released during the solidification of the outer core. These processes act in concert to maintain the core's high temperature over billions of years.
