According to Jewish tradition, up until the time of Hezekiah each month was a perfect 30 day span and each year was 360 days exactly and it was not until Hezekiah's days that the earth's rotation changed to give us the calendar we have today.

Archaeologists have discovered that all over the world, there are nothing but 360 day calendars in use up to about the 8th century BC.  The earliest calendars using something other than a 360-day year are dated no earlier than the 7th-8th century BC.

I've often wondered if it'll change again before/when the false messiah comes in the last days since prophecy talks about a 30-day month in connection with the anti-moshiach. The Bible does tell us that in the end times there will be signs in the skies.  Maybe a change back to the earth's original orbit would be such a sign.  Planet X may even be what will put the earth's rotation back to its original orbit.

Right now the length of the year is slowly shrinking.  The earliest measurements were 365.2422 days and now it's under 365.242.  So maybe if we just wait long enough it'll go back to that orbit anyway without any intervention!

Shalom,

Joe