Why is the actual mean temperature of the moon so much lower than the effective temperature? NASA lists the effective temperature of the moon at 270.6 kelvin. The mean temperature of the moon at the equator is 220 kelvin. With no atmospheric effects, why is the surface temperature so much lower than the effective temperature predicts? Rephrasing for clarity: What factor is NOT part of the effective temperature formula that so dramatically affects the actual temperature of the moon? Normally one would say atmospheric effects, but the moon effectively has no atmosphere - certainly not enough of one to cause this big of a discrepancy.