The leap second is dead. Long live the leap hour?

The leap second — a periodic adjustment that keeps the relentless march of the world’s atomic clocks in sync with the planet’s naturally varying rotation — could be scrapped as soon as October. The world’s timekeeping authorities want to fast-track a change, already planned for 2035, because we’re facing the possibility of the first-ever negative leap second — meaning that clocks must skip, rather than gain, a second. The unprecedented event could cause chaos, say researchers — especially because the leap second is handled slightly differently across crucial infrastructure such as electrical grids and financial systems. Better, say timekeepers, would be a leap hour — which would mean adjustments only once in hundreds, or thousands, of years.

What time is it on the Moon?

Scientists are working to define the first official time for the Moon. This will help to coordinate lunar missions and allow creation of a lunar satellite navigation system. Defining lunar time will involve installing at least three master clocks that tick at the Moon’s natural pace, which is slightly faster than time on Earth because the Moon has weaker gravity. The clocks’ combined output could then be synchronised to Earth time.

Extreme numbers get new names

By the 2030s, the world will generate around a yottabyte of data per year — that’s 10²⁴ bytes, or the amount that would fit on DVDs stacked all the way to Mars. The data boom has prompted the governors of the metric system to agree on new prefixes to describe the outrageously big and small. The prefixes ronna and quetta represent 10²⁷ and 10³⁰, and ronto and quecto signify 10⁻²⁷ and 10⁻³⁰. Earth weighs around one ronnagram, and an electron’s mass is about one quectogram. Ronna and quetta might sound strange now, but so did giga and tera once, says metrologist Olivier Pellegrino. This is the first update to the prefix system since 1991, when zetta (10²¹), zepto (10⁻²¹), yotta (10²⁴) and yocto (10⁻²⁴) were added.

World votes to ditch leap seconds

Metrologists have agreed to stop adding ‘leap seconds’ to official clocks to keep them in sync with variations in Earth’s rotation. Leap seconds can disrupt systems based on precise timekeeping, because there’s no set way to integrate them (Google, for example, smears out the extra second in the 24 hours around midnight at coordinated universal time). To make matters worse, Earth’s rotation has sped up since 2020 — normally, over the long term, Earth’s rotation slows because of the pull of the Moon. So, for the first time, a leap second might need to be removed rather than added. The practice of adding leap seconds will be put on hold from 2035.