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 length of the day hasn’t always been the same. The length of the *year* has. A year isn’t defined by “how many days it takes to get back to the same point in the orbit,” it’s defined by “how *long* it takes to get back to the same point in the orbit.” The year 1,000,000,000 BCE was the same length as the year 2022 CE.

We’re also not counting years back then with any degree of accuracy. We have no idea “exactly when” the asteroid hit Chicxulub, all we can do is estimate it.