By definition, today is the time it takes for the Earth to complete a full rotation on itself. Even if our planet is generally stationary, its motion remains influenced by a large number of factors. Differences associated with tides, influence of the moon, atmosphere, etc.can accelerate or slow down its rotation.

So in 2020, Earth seemed to want to make time pass faster (and we understand that). It actually lasted several days shorter than average. Rest assured, however, this doesn’t count in minutes: the shortest day was July 19, 2020, with 1.4602ms less than normal. A nuance however could be important.

In fact, our traditional timescale – Coordinated Universal Time (UTC) – does not take this shift into account. It is based on atomic clocks and remains stable, despite differences in the Earth’s rotation. Cumulatively, however, these small differences could cause a gap between UTC and the reality of our planet, which may be enough to disrupt some scientific instruments.