The Earth is slowing down. Not so much that we might perceive it, but it is. And it adds up.
So say scientists, according to NASA, and as a result, one second — a “leap second” — will be added to our clocks on Tuesday.
“Earth’s rotation is gradually slowing down a bit, so leap seconds are a way to account for that,” said Daniel MacMillan of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. He was quoted in a news release put out by NASA.
The planet’s rotation is supposed to be 86,400 seconds, but lately it’s been 86,400.002 seconds. That extra bit makes a difference, day after day after day.
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So the plan is to add a second, and it’s been done before. This leap second will be the fourth since 2000, and before that, they were added at an average rate of one per year going back to 1972, when they were implemented, NASA says.
It’s unclear what effect adding a second will have, although NASA says that “previous leap seconds have created challenges for some computer systems and generated some calls to abandon them altogether.”
NASA says a range of factors can alter the speed of the planet’s rotation, from gravity wars between the Earth, moon and sun, to tides, earthquakes, and even El Nino.
Leap seconds are added on Dec. 31 or June 30. This one will be added after 23:59:59 Coordinated Universal Time or UTC. UTC is four hours ahead of Eastern Daylight Time, so the occurrence is set for 8 p.m. Tuesday in Boston.
And this may be the last one, or among the last.
“Proposals have been made to abolish the leap second. No decision about this is expected until late 2015 at the earliest, by the International Telecommunication Union, a specialized agency of the United Nations that addresses issues in information and communication technologies,” NASA says.
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