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## Main Question or Discussion Point

In the 19th century Lord Kelvin made the first numerical calculation of the age of the earth not based on the Bible.From his initial guess that the earth started as a molten rock and that today the temperature of the interior increases at a certain rate as you approach the center, he got an age of about 100 million years.(Part of the reason for his error was that he had no way of knowing that radioactive decay was an additional source of heat)

I want to ask a simpler question; How would you calculate the surface temperature of a 10,000

mile solid sphere of a very hot rock initially at 5000 degrees K in the vacuum of space. Assume it is of uniform density and a perfect black body.Also assume no atmosphere and the sun is 10 billion miles away and contributes nothing. What is its surface temperature after one million years or 10 million years.

I want to ask a simpler question; How would you calculate the surface temperature of a 10,000

mile solid sphere of a very hot rock initially at 5000 degrees K in the vacuum of space. Assume it is of uniform density and a perfect black body.Also assume no atmosphere and the sun is 10 billion miles away and contributes nothing. What is its surface temperature after one million years or 10 million years.