I fixed it for you wrote for Slate on Friday Happy Winter Solstice Phil Plait axial tilt Christmas card Via the Bad Astronomer a nice overview of axial tilt and the solstice real reason for the season what causes the seasons Christmas card Slate.com what causes the seasons winter solstice axial tilt Slate.com Slate.com has a declination of zero degrees Via the Bad Astronomer Christmas card informative article winter solstice