Researchers speculate that the permanently shadowed craters on the Moon may be the coldest places in the Solar System, with temperatures reaching -248.15 degrees Celsius.
The universe is extremely cold. The temperature of outer space is -270.45 degrees Celsius, just slightly above absolute zero (-273.15 degrees Celsius), the point at which molecular motion ceases. However, this temperature is not uniform throughout the Solar System. For instance, some “empty” regions of space are much colder than the planets, moons, or asteroids because they lack any materials to absorb energy from the Sun. Excluding these “empty” spaces, the coldest place in the Solar System could be quite close to Earth, according to Live Science.
Lunar craters. (Photo: Science News)
In 2009, NASA’s Lunar Reconnaissance Orbiter, an automated spacecraft designed to help scientists better understand conditions on the Moon, provided data revealing that the permanently shadowed craters at the Moon’s south pole could be the coldest places in the Solar System. This hypothesis was later supported by researcher Patrick O’Brien and his advisor Shane Byrne, a planetary scientist at the University of Arizona.
According to O’Brien and Byrne, a crater is considered shadowed if it is obscured not only from direct sunlight but also from secondary heat sources, such as sunlight reflected from nearby illuminated surfaces or thermal radiation from warmer areas. These craters also have rims high enough that sunlight never reaches the crater floor, making them extremely cold. The research by O’Brien and Byrne indicates that permanently shadowed regions that have not been illuminated by the Sun for billions of years have estimated temperatures around -248.15 degrees Celsius, or even colder. “I am quite certain that this is the coldest temperature in the inner Solar System (from Mercury to Mars) and also colder than the estimated average surface temperature of Pluto.“ Ian Crawford, a professor of planetary science and astrobiology at Birkbeck, University of London, stated.
The average surface temperature of Pluto is -232.75 degrees Celsius. However, the shadowed craters on the Moon may not be as cold as the Oort Cloud, a shell of icy debris located beyond the orbit of Neptune. The difference depends on whether or not we include the Oort Cloud within the Solar System.
The Oort Cloud was once thought to be the “most distant region of the Solar System”, but it is also considered “outside” the system. This ambiguity means it is sometimes viewed as part of the Solar System, while many consider it the boundary between the Solar System and interstellar space. According to Northwestern University in Illinois, temperatures in the Oort Cloud can drop to -268.5 degrees Celsius, which is significantly colder than the Moon. However, if we do not include the Oort Cloud in the system, the coldest place in the Solar System is likely on the Moon.
On Earth, even the coldest temperatures recorded in Antarctica are much warmer than the lunar craters or the Oort Cloud. The coldest temperature ever recorded on land was on July 21, 1983, at the Vostok Station in Antarctica (-89.2 degrees Celsius), according to the World Meteorological Organization.
However, scientists can create even colder temperatures naturally on Earth compared to the lunar craters or the Oort Cloud. Last year, a research team from Germany broke the record for the coldest temperature ever achieved in a laboratory at -273.15 degrees Celsius by dropping gas from a 120-meter-high tower.
