June 30th Gets a Leap Second Because Earth’s Rotation is Slowing Down

Specifically, June 30 will last 86,401 seconds and not 86,400, as is customary for run-of-the-mill days.

Washington DC, Jun 29: NASA has explained that June 30, 2015 will officially be a bit longer than usual because an extra second or “leap” second will be added.

Leap seconds are added by experts at NASA to make up for differences between two internationally-accepted time standards due to a gradual slowing down of the Earth’s rotation. Internet giants Reddit, LinkedIn, Gizmodo and Foursquare reportedly experienced glitches as their network clocks failed to read the extra second got added to the Coordinated Universal Time (UTC).

The UTC, also known as atomic time, is the duration of one second, based on the electromagnetic transitions in the atoms of Cesium, which are rather predictable. The cesium clock is accurate to one second in 1,400,000 years. The mean solar day is about 86,400.002 seconds long. That’s because a gravitational tug-of-war between the Earth and the moon is causing our planet’s rotation to slow down, making the days a wee bit longer as the years roll on. Although the difference of two milliseconds isn’t very huge but it happens every day and cumulatively it adds up to nearly a second in a year. That’s because, as we first learned back in January, we’re all being gifted a leap second on June 30th.

Normally the clock would tick from 23:59:59 to 00:00:00 the next day.

Previous leap seconds have created challenges for some computer systems and generated some calls to abandon them altogether.

NASA scientists further explained that it is not that predictable to add a leap second as everyone would think.

Like the last one, the ‘leap’ second that is going to be added to the UTC Tuesday may cause a few hiccups although the global IT giants have taken care of the glitch well in advance. That’s where leap seconds come in. Meanwhile, it’s learnt that Space Missions world over do not take up launchings on the day a ‘leap’ second is added to avoid the risk of malfunctioning of their computers.

Bernard says that for the average person, it’s barely noticeable, adding that over a lifetime, an individual may experience 60 leap seconds.

Scientists do not know exactly why fewer leap seconds have been needed lately. Because the observing stations are spread out across the globe, the signal from a quasar will take longer to reach some stations than others. This is because Earth’s rotation isn’t slowing at a constant rate.

NASA is developing a new system to more accurately measure the Earth’s rotation.

Despite proposals to abolish the leap second, no decision has been made by the worldwide Telecommunication Union, a specialized agency of the United Nations that addresses issues in information and communication technologies, explains Elizabeth Zubritsky of NASA’s Goddard Space Flight Center.



NASA Explains Why June 30 Will be 1 Second Longer


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