Today marks the shortest day of the year, as the Earth’s rotation speed around its axis continues to accelerate, causing a slight reduction in the normal day’s length.
According to BBC Science Focus, although daytime is typically longer during the summer months, the Earth’s rotation cycle will finish approximately 1.3 milliseconds earlier than usual on this specific day. Normally, our planet completes a full rotation on its axis in exactly 24 hours—or 86,400 seconds—yet minor fluctuations in this timing frequently occur.
The International Earth Rotation and Reference Systems Service (IERS), a scientific body dedicated to tracking such variations, continually measures the precise length of each day. In 2020, the IERS detected an acceleration in Earth’s rotational speed, and since then, this trend has gradually intensified.
Besides today, the IERS data has also indicated that two other days—July 22 and August 5—will also experience shorter-than-average durations. Significantly, August 5 coincides with the date when the Moon will reach its farthest point from Earth’s equator.
