Today, you might already know, is the winter solstice. That means for people living in the Northern Hemisphere, it's the longest night of the year. However, as science blogger Colin Schultz points out, tonight will also be the longest night ever. At any location in the Northern Hemisphere, in other words, tonight's period of darkness will be slightly longer than any other, ever — at least, since the planet started spinning right around the time it was first formed some 4.5 billion years ago. The reason is that the rotation of the Earth is slowing over time. Every year, scientists...