"The difference between Chang'e 4's reading and the Apollo missions' is "probably due to the difference in lunar soil composition between the two sides of the moon. We still need more careful analysis," Zhang He, executive director of the Chang'e 4 probe project, told Xinhua.
In other words, something about the lunar dirt where Chang'e 4 sits is probably causing the soil to retain less heat overnight than the Apollo landing sites did. But researchers still aren't sure what that something is."
I suppose the explanation may be that the Earth heats the "light side" of the Moon with infrared radiation emitted towards the Moon. But maybe I am wrong and the power of infrared radiation emitted there is too weak.
From some time I have been doing experiments indicating the possibility of cooling the Earth by the Moon. My hypothesis is that cold infrared radiation cools a surface of Earth. I have made already experiments with ice which suggest that infrared radiation was able to cool. I have bought a thermographic camera and tested which surfaces reflect cold infrared radiation. The camera could measure temperature in a range -40 to +330 degree of Celsjus.
January 19th 2019 during night I measured temperature of the Moon and sky without clouds. Temperature of air was -5°C.. Temperature of the Moon was - 39°C.
""The tunnels offer a perfect radiation shield and a very benign thermal environment," says Robinson. "Once you get down to 2 meters under the surface of the Moon, the temperature remains fairly constant, probably around -30 to -40 degrees C."
I checked temperature of sky without clouds. It was -43°C