The National Aeronautics and Space Administration mission will join timekeepers around the world to add a leap second to its clocks on Saturday night, it said in an official statement. The Solar Dynamics Observatory, which monitors the sun, will also add a leap second to its clock.

The leap second is being added to make sure that SDO is in sync with the Coordinated Universal Time, the statement said. The Earth’s rotation is gradually slowing down over time. Between 23:59:59 and 00:00:00, digital clocks will record the extra second as 23:59:60.

“We all have to use the same time to make sure our collision avoidance programs are accurate. So we all add a leap second to the end of 2016, delaying 2017 by one second,” said Dean Pesnell, the project scientist for SDO.

The International Earth Rotation and Reference Systems Service in Paris usually decided when leap seconds need to be added, reports SkyNews. The announcement is made six months in advance to allow financial systems and other applications relying on precise timing to programme their computers.

The leap second is being added for the 27th time on Saturday night since 1972.