Time to celebrate! It’s the shortest day of the year in the northern hemisphere, and the longest in the southern.  The first day of Winter here, and the first of Summer down south.  Although as a Canadian, Winter usually starts a lot earlier. Why do we have seasons? A common misconception is that the Earth is closer to the Sun in Summer, and further in Winter.  Well I can tell you the Earth reaches perihelion (its closest point to the Sun) on January 3rd, and it certainly isn’t a warm day in Canada, historically speaking. So the reason for the...