Something Deep Inside Earth Keeps Messing With the Length of Our Days

For practical purposes, we say that one day—the time it takes for Earth to rotate once on its axis—equates to 24 hours. In reality, different factors across different timescales influence how quickly our planet turns, which scientists have yet to fully understand.

But new findings, published today in Nature, may finally solve at least one of these outstanding mysteries, namely how Earth’s rotation changes every couple of decades. According to the study, the multidecadal changes in Earth’s behavior come from…