Based on the textbook definition of temperature, space is hot, at least here in the Solar System. The molecules in space are individually moving very fast, which means that each one has a lot of energy, and temperature is usually defined as the average kinetic energy of the molecules in a substance. But there are so few molecules in space that even though each one has a lot of energy, the total amount of heat energy is small, which means it doesn’t warm things up very much. It may be warm in theory, but it feels cold in practice.
