> You can measure and verify that the Sun can't be keeping the Earth this warm, if it was just down to the Sun this place would be uninhabitable. This is somew

> You can measure and verify that the Sun can't be keeping the Earth this warm, if it was just down to the Sun this place would be uninhabitable. This is somewhat misleading because the Sun is pretty much the sole energy source for keeping the surface of the Earth warm: > Despite its geological significance, this heat energy coming from Earth's interior is actually only 0.03% of Earth's total energy budget at the surface, which is dominated by 173,000 TW of incoming solar radiation. [1] The problem posed by Kelvin was the the interior of the Earth was too warm, which may affect long-term habitability because plate tectonics plays a role in regulating the atmosphere's CO2 levels (or so I've heard), but of course nobody at Kelvin's time knew that. Kelvin wasn't asking "Why isn't the Earth a dead planet?" [1] https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget