Surprisingly, I've found explanations that it's due to variation in the year and day. Remember, the year is based on the physical phenomena of goin'round the su

Surprisingly, I've found explanations that it's due to variation in the year and day. Remember, the year is based on the physical phenomena of goin'round the sun, and so we have the issue of theory meeting practice, where our ideal of a year fails to model the truly complex dynamics of the actual earth's orbit. There are errors being introduced due to the moon slowing our spin, other planets distorting our orbit, and other such subtle and difficult-to-account-for cumulative errors from ideal steady-state. So even of the second was defined as slightly longer, we'd still have to issue corrective leap seconds. I meant to look into this particular thing more closely last time I read about leap seconds here, so I'm glad for the reminder. If anyone has actual details and references about these effects, I'd be much obliged.