1. Looking at the Northern Hemisphere, night is on the left and day is on the right.
2. Advancing to December, night on the left becomes longer and days become shorter.
3. It is the relative tilt of Earth, as it goes around the sun, that causes our seasons.
4. Fewer hours of sunshine result in our colder winter temperatures.
TAG: By December 21 Earth’s North Pole will be tilted 23.5 degrees away from the sun which decreases temperatures. When the Northern Hemisphere is tilted towards the sun temperatures can double.
This video is also playable via NASAviz (iPad App): “Follow the Line” Oct 31, 2013.