A new study has re-examined the claim that the COVID-19 lockdown affected temperatures on the Moon, finding that they may have dropped a little at the Moon surface prior to the pandemic.
COVID-19 wrought – and continues to wreak – havoc on the Earth. According to a study in 2024, its effects were not limited to our planet; the surface of the Moon may have been indirectly affected by the resulting lockdown.
At the beginning of the COVID-19 pandemic, before vaccines were developed, lockdowns were used by various governments around the world in an attempt to stop or slow the spread of the disease. At one point, at the beginning of April 2020, around half the world’s population had been ordered to stay at home, or were under some sort of curfew.
This massive change to human life patterns had an immediate effect on wildlife and, of course, our CO2 emissions. Now, thanks to a team investigating lunar nighttime surface temperatures, we know that it may have affected the Moon too.
The Moon is tidally locked to Earth, meaning that its rotation speed around its own axis matches the time it takes to orbit around the Earth, and so the near side always faces Earth. The team chose six sites on the surface of the near side, selected to be as flat as possible to limit local effects on temperature as much as possible. Analyzing the Diviner Reduced Data Record from NASA’s PDS Geosciences Node over six years, they found an anomaly.
“Lunar night-time surface temperatures of six different sites on the Moon’s nearside were analysed during the period 2017–2023. Results showed an anomalous dip in the lunar night-time surface temperatures for all the sites during April–May 2020, the strict COVID-19 global lockdown period, when compared to the values of the same period during the previous and subsequent years,” the team explained in their study, published in 2024.
“Since the terrestrial radiation has also showed a significant reduction during that time, the anomalous decrease observed in lunar surface temperatures is attributed to the COVID-19 global lockdown effect. [The] Moon has possibly experienced the effect of COVID-19 lockdown, visualized as an anomalous decrease in lunar night-time surface temperatures during that period.”
Overall, the lunar night temperature difference was around 8-10 Kelvin. The team compared the temperature differences to sunspot activity that could have contributed to such a dip, but found no correlation.
The reason for the dip, according to the team, is the amount of radiation received from the Earth. During the lunar night on the near side, the Moon receives its radiation as it is reflected off the surface of the Earth. As human activities changed, and fewer pollutants were put into our atmosphere, this had a knock-on effect, with less radiation reflected toward the Moon. And so, COVID-19 lockdowns appeared to have, inadvertently, briefly made the surface of the Moon colder.
However, a new analysis by researchers at the Missouri University of Science and Technology (Missouri S&T) and the University of West Indies (UWI) in St. Augustine, Trinidad and Tobago, has challenged this conclusion.
“When one of my colleagues first showed me this article written by the other researchers, we both wondered – could this be real?” Dr William Schonberg, a Missouri S&T professor of civil engineering who has researched space-related topics for almost four decades, said in a statement.
“The idea that our activity, or lack of activity, on Earth would have significant influence on the temperatures of the Moon – which is almost 240,000 miles [386,243 kilometers] from us – didn’t seem likely, but we decided to keep an open mind and conduct additional research.”
The new team used the same data from the original study, performing their own analysis of it, as well as further statistical analysis, and data on the temperature of the top of the Earth’s atmosphere. Unlike the first team, they found that the dip in temperature preceded the 2020 lockdowns, with dips in 2018 and 2019.
“Our analysis, while it shows the temperature reduction during the months of the lockdown, also reveals that the downward trend in temperatures began as far back as 2019, and that other similar trends in the temperature data appear in roughly two-year cycles,” the new team writes in their study.
“Considering the study by Mazhar et al (2021), which concluded that there is no effect at the top of the atmosphere from the global lockdown during COVID-19, and the insights by Prof. Schulze-Makuch, we conclude that the reduced nighttime temperatures on the lunar surface cannot be unequivocally attributed reduced anthropogenic activities during the global lockdown due to COVID-19.”
So far, little research has gone into how activity on Earth can affect the temperature of the Moon, with studies, perhaps understandably, focusing on the reverse. The team does not rule out the possibility of Earth affecting the Moon’s temperature, but states that it is a “bit of a stretch” to suggest attribute dips in temperature to the COVID-19 lockdowns.
“During the Moon’s nighttime, there is a small possibility that heat and radiation from Earth might have a very small effect on the lunar surface temperatures,” Schonberg added. “But this influence would probably be so minimal that it would be difficult to measure or even notice.”
The study is published in Monthly Notices of the Royal Astronomical Society: Letters.
