Eli5: If millions of years ago a day had only 22 hours, does science count those years differently, or is the standard always 24 hours? Aren’t we then missing a few years which we need to add up?

Question

Eli5: If millions of years ago a day had only 22 hours, does science count those years differently, or is the standard always 24 hours? Aren’t we then missing a few years which we need to add up?

In: 7

Answer 1

The Earth would have had ~398 days per year. The reason that days have gotten longer is that the presence of the moon has slowed the rotation of the Earth relative to its own axis. That does not affect the rotation of the Earth around the sun, which is what determines the length of a year.