Owing to an incredibly small discrepancy between the atomic clock length of a year and the time it takes for the sun to orbit the earth, and the dogged insistence of scientists for being as close as possible to correct all the time, tomorrow is the most recent in a series of days where time goes a bit weird momentarily due to the addition of a leap second. This means 30th June 2012 will last for 86,401 seconds instead of the usual 86,400. Internet mathematician and pedant Matt Parker reports this as an 0.00116% increase on the usual number of seconds in a day.

The supplementary second will rear its head a second before midnight tomorrow, so if you watch the (right kind of) clock at that time you should be able to see, for an instant, 23:59.60 UTC (Coordinated Universal Time). Watch out for discussion of the momentous moment on Twitter, and keep your browser trained on the USA’s Time.gov for a glimpse of the irregular instant.

The last leap second was added on December 31st, 2008 and tomorrow’s juxtaposed jiffy will be the 25th such second to have been added since their introduction in 1971. There is much debate as to whether the adding of leap seconds should continue, as it causes problems for computers, due to it being difficult to predict exactly when a new leap second will be needed. While a decision was due to be made in January 2012, this has been postponed until 2015 when the World Radio Conference will decide on the issue. For more information about leap seconds, read this page written by Cambridge University’s Marcus Kuhn, or this Wikipedia article.

What do you plan on using/did you use your extra second for? Comments below.