W hy Is Outer Space Cold? Author; ROGELIO PEREZ CASADIEGO Why is the outer space cold? If it is assumed to be mostly empty and temperature is a characteristic of the energy level of matter. All vacuum due to its lack of substance is a thermal insulator, but it is well known that in outer space astronauts when protected by the shade of our planet may experience temperatures of -180°C, but when they are facing the radiation of the sun the temperature they can withstand is 120°C. Of course this is possible thanks to space suits, now for thermal conduction a substance is necessary, by which the outer space should not be cold if this vacuum, Then we wonder what substance fills the outer space by originating its cold? Since the entire space of the universe is very cold, which has approximate temperatures from -180°C to almost 0 k. to answer this question we must know that the universe in its beginning was quite the opposite, this was very hot, due to the ion soup of the great plasma that fi