Without the sun, would the tempeture of the earth be absolute zero?
Well, there geothermal heat generated by radioactive decay at Earth’s core, and Isaac Asimov’s The Measure of the Universe says the universe’s average temperature is 3[sup]o[/sup] Kelvin, so… no.
No, you’d get some tiny amounts of energy in the form of radioactive decay, residual geothermal heat from the formation of the Earth, unbelievably tiny amounts from starlight, and friction and impact energy from meteorite impacts. Absolute zero is an idea that has never (to my knowledge, anyway) been observed, even in the laboratory.
Heat from the core would make it a bit warmer than 2.7°K, the temperature of the cosmic microwave background radiation.
No