BOULDER, Colo. — Most people know why, every four years, February has 29 days. The leap day is added to keep our calendars in line with the seasons, since it actually takes the Earth about 365.25 days to go around the sun.
But fewer people are familiar with the concept of leap seconds. Since 1972, 37 leap seconds have been added to the world’s atomic clocks in an effort to keep atomic time in sync with astronomical time. Without those leap seconds, the time on our clocks would continue to diverge from time as measured by the sun. Within a century or so, humans would no longer say it's noon when the sun is at its highest point in the sky.
Scientists at the National Institute of Standards and Technology in Boulder are in charge of adding the occasional leap seconds, but recently they were part of a global discussion about getting rid of leap seconds altogether.
NIST physicist Judah Levine said the problem is that leap seconds mess with computing systems that rely on extremely accurate timekeeping.
“There’s an interruption in the clocks when you have financial transactions, or commercial transactions and power grids, etc.,” Dr. Levine explained.
To solve that problem, Levine has proposed replacing the leap second with a leap minute. A leap minute wouldn’t be needed as frequently, perhaps only once a century. He’s also proposing we change the leap minute to a “time smear” which essentially means gradually adding the minute by slowing the clocks down. That way, computers wouldn’t get confused by the sudden time jump.
Levine said most scientists want to maintain the connection between atomic time and astronomical time, even if they’re only diverging slightly.
“When the sun is up, it's day time. When the sun is down, it’s night. And that means there’s an implicit everyday link between time and astronomy,” Levine said.
Levine doesn’t expect an answer to the problem anytime soon, but hopes nations can agree on something rather than leaving it for later generations to decide.
