Is Tonight the Longest Night in History?
For those of us residing in the Northern Hemisphere tonight marks the winter solstice, which also signals the longest night of the year. However, contrary to popular belief and multiple news sources, tonight will NOT be the longest night in history. Let me explain.
Scientists have found that the speed of the Earth’s axial rotation is slowing, albeit over a very long period of time, allowing the earth to go from having 6-hour days to 24-hour days. According to Joseph Stromberg, writing for Vox Media,
“The moon’s gravity pulls ocean water slightly toward and away from it, causing tides. But because of the alignment of the two bodies, the resulting bulge of water is slightly ahead of the spot on Earth that’s directly under the moon. As a result, the Earth encounters just a bit of friction from this bulge of water as it rotates, slowing it down slightly.
The phenomenon — called tidal acceleration — also allows the moon to drift slightly farther away from Earth over time. (It’s also what’s led the same face of the moon to always faces Earth as it rotates around us, and eventually, if things went on long enough, the same face of Earth would always face the moon as well, a phenomenon called tidal locking.)”
If this were a linear process, the length of the solstice night would increase by a fraction of a millisecond every year. But it doesn’t. A multitude of other geological factors, such as the melting of the polar ice caps and the movement of the Earth’s crust in relation to its core, make this a fluctuating process. In other words, the length of the annual solstice night does not necessarily get longer every year.
So, to keep up with the earth’s ever changing axial rotation speed, every few years official timekeepers add or subtract a leap second from the clock, the last of which was added on June 30th in 2012. Though there has been much confusion about the scheduling of said leap seconds for 2014, tonight will not become the longest night in history as there will be no leap seconds added to the clock on December 31st.
Image Copyright: Public Domain via Wiki Commons
The links in the referenced article have been redirected from Wikipedia.org to Princeton.edu. The current version of this article differs from the original posted this morning, as the information cited from the article published by Vox Media contained scientifically inaccurate information which has since been corrected. Although this fact sucks, writers are only human, so that’s that.