If the earth did not have an atmosphere, temperature extremes between day and night would

If the Earth lacked an atmosphere, temperature extremes between day and night would increase significantly. The atmosphere acts as a protective blanket that regulates surface temperature through the greenhouse effect and heat distribution. During the day, the atmosphere absorbs and scatters incoming solar radiation, preventing the surface from becoming excessively hot. At night, it traps outgoing longwave radiation (terrestrial radiation), preventing heat from escaping rapidly into space. Without this mechanism, the Earth would experience intense heating during the day and extreme cooling at night, similar to the Moon or Mercury. For instance, on bodies like the Moon or thin-atmosphere planets, temperatures can drop as low as -180°C (-290°F) at night because there is no atmosphere to hold in the heat [t3]. Consequently, the diurnal temperature range—the difference between the daily maximum and minimum—would expand drastically [t4][t6].

Sources

1. [1] https://science.nasa.gov/solar-system/temperatures-across-our-solar-system/