People were meeting for sunrise at Stonehenge this morning as today was the shortest day of the year in the northern Hemisphere. This is the Northern winter solstice.
Apparently the day was less that 8 hours long, although it was so cloudy and grey it might have been shorter for all I could tell.
Of course on the equator days and nights are pretty much of equal length and I presume the Southern Hemisphere had its longest day either yesterday or today. What will it be like in six months when it’s summer here again? Who knows.
When the sum rose this morning it was on the shortest day of the year. Now the days up here in the Northern Hemisphere will slowly start to lengthen again. At first at a minute or two a day, but gradually a few more minutes around spring time. Then as the Summer solstice approaches the number of minutes slows down. Finally after that the process goes into reverse and the days begin to wane again. So the great cycle of light and dark tumbles along North and South. Only on the equator are day and night lengths balanced out. The cause? Earth is tipped at an angle, so for six months of the year one half of the planet gets more light than the other (which also proves the Earth is a globe).
Sunlight streaming through the window Shines on Christmas cards and books, ornaments my sewing kit. As the sun rises it also travels south in the sky in winter. Then in the afternoon it appears to move downwards and West. So because of the way the earth is tipped on its axis the position on the sky moves in arcs that tip further south in the winter and further north in summer. So the sun appears overhead eventually.
If the Earth was rotating on a vertical axis at 90° to the plane of the solar system, then day length would stay the same all over the world. 12 hours day and 12 hours night. There would be no seasons. There would probably be no poles as all parts of the earth would receive the same amount of heat from the sun.
Instead the tip of the axis means that the day length changes over the years. So at the solstices the earth has turned to have its poles either closest or furthest apart from the sun. It’s also complicated by the earth travelling in an elliptical orbit round the sun. In the summer in the North of the world the sun is actually slightly further away from the earth than in the winter.
Anyway enough of celestial mechanics. Don’t get me started on the moon! Happy Boxing day. X
Mallaband-Brown 