Tonight's Leap Second Could Completely Screw Up the Internet, but It Probably Won't

Read: Predicting the Digital Apocalypse with Author Douglas Coupland

Every few years, a group of scientists tasked with keeping an eye on standard, universal time tack on a "leap second" to make up for the extremely gradual slowing of Earth's rotation and keep our clocks on track. Tuesday is one of those days. Though we won't notice that today lasts a little longer than normal, the leap second has a history of throwing off computer systems, stock markets, and online marketplaces that rely on a synchronized measure of time. The 2012 leap second crashed Reddit, Foursquare, and LinkedIn and delayed dozens of Qantas flights when their reservation system failed.

Tonight's leap second will be the first to go down during stock market trading hours since the markets went electronic. About $4.6 million is traded around the world every second, and exchanges across the globe are trying to find ways to avoid any glitches that could compromise an insane amount of cash transfers.

At 7:59:59 PM EST on Tuesday, clocks will not roll over to 8:00:00 as God and all natural law intended. Instead, for a single second, they will hit 7:59:60, before turning 8 PM, which may befuddle computers and send them spiraling toward some sort of technological apocalypse. Luckily, we can see this coming, so US exchanges are ending after-hours trading early and international markets are recalibrating their clocks before the leap second hits. Things will probably be OK.

If you are looking for a way to spend your extra 00:01, John Oliver's got you covered.