How do you know the exact temperature if we never been there?

Scientists determine the temperature of distant places, such as other planets or celestial bodies, using various methods, including remote sensing and mathematical modeling. Instruments like spectrometers analyze the light emitted or reflected by these bodies, allowing researchers to infer temperature based on the characteristics of that light. Additionally, computer simulations can model atmospheric conditions and heat transfer processes, providing estimates even for locations we haven't physically visited.