| WHAT ARE THE COLDEST AND THE HOTTEST OBJECTS IN THE UNIVERSE? |
Absolute zero, the temperature at which thermal energy is theoretically zero and which is therefore generally considered the coldest possible temperature, is -273.15°C Celsius (or 0°K on the absolute Kelvin scale). The cosmic microwave background radiation which uniformly permeates all of space has a temperature of 2.725°K, or around -270°C.
Within the Solar System, the average temperature on Pluto is around -235°C, on Neptune around -220°C, on Uranus -210°C, on Saturn -184°C and on Jupiter -153°C. The temperature on Mars varies between about -87°C and -5°C, with an average of around -46°C. The lowest natural temperature on Earth (recorded at Vostok, Antarctica in 1983) is -89°C; the highest surface temperature on Earth (recorded at Al 'Aziziyah, Libya in 1922) is 58°C; the mean overall temperature on Earth is 14°C.
Water at standard pressure on Earth freezes at 0°C, and boils at 100°C. Lead melts at around 328°C, iron at 1,535°C, titanium at 1,668°C, and carbon in the range of 3,550°C to 3,675°C depending on the type. The temperature of an incandescent light bulb is round 2,200°C. A lightning bolt can reach 28,000°C. The temperature in a working fusion reactor is around 100 million °C. The highest man-made temperature, about 2 billion °C, was generated by the so-called Z-Machine at the Sandia National Laboratories in Albuquerque, New Mexico.
Continuing through the Solar System, the mean daytime temperature on the Moon is 107°C, while the mean nighttime temperature is -153°C. The temperature on Venus is a relatively uniform 462°C. The surface temperature on Mercury varies between 466°C on the sunward side and -184°C on the other side. The surface of the Sun has a temperature of about 5,700°C, and the core of the Sun about 15 million °C (although the temperature in the Sun’s corona can rise to over 2 million °C).
Red dwarf and red giant stars typically have surface temperatures in the range of 2,500°C to 3,500°C. Blue supergiant and hypergiant stars have surface temperatures ranging anywhere from 3,500°C to 35,000°C. The explosion of a supernova can generate temperatures in excess of 100 billion °C. The Planck Temperature is the temperature of the universe at 1 Planck Time after the Big Bang, and is considered the de facto maximum possible temperature. It has been calculated to be approximately 1.4 × 1032°C (140,000,000,000,000,000,000,000,000,000,000°C).