Setup and Support
Day and Night
Place the sun anywhere on the outermost ring. Now the sun is carried around as you turn the globe. Notice that the observer can see the sun when it is above the horizon plate but not when it is below.
Sun above the horizon = day;
Sun below horizon = night.
The globe makes one turn in a 24-hour day. The sun does not slide on the ring during a day, it is just carried around by the turning of the globe.
Directions on the Horizon Globe are established the same way as on Earth. The turning axis defines North and South. In the northern hemisphere North is the top end of the axis. If the observer faces south, the globe turns clockwise causing the sun to rise in the east and set in the west.
Seasons are illustrated by the Horizon Globe by moving the sun to different positions on the ecliptic ring. When the sun is closest to the North Pole it is summer.
When the sun moves from one point on the ecliptic ring to another, three changes take place:
1. The sun passes higher or lower over the observer at noon.
2. The sun rises and sets in different directions.
3. The sun is above the horizon for a different fraction of one turn of the globe.
Seasonal motion of the Sun
In order for the seasons to change throughout the year, the sun must slowly slide along the ecliptic. It slips back one degree per day, almost imperceptible, but it adds up to about 30 degrees per month, or 90 degrees every three months.