This page contains the answers to the questions embedded throughout the Tutorial on Earth/Sun Relations and Seasons.
The North Star, or Polaris
South. The subsolar point will not move north of the Tropic of Cancer. After the solstice, the Sun’s direct rays will move toward the south (though the southward movement is so slow it is not apparent for a few days; “solstice” means “Sun stands”: the Sun’s rays reach the Tropic, and appear to stop for a while before moving south again). The subsolar point will get to the equator three months later, and to the Tropic of Capricorn about 3 months after that.
12 hours. You can get at this in a couple of ways. One, the circle of illumination is a great circle, and so is the equator. Great circles always bisect each other, so if the equator cuts the circle of illumination in half, it must get 12 hours of light and 12 hours of dark. Or, you can just figure that there are 0 hours of daylight at the South Pole and 24 at the North Pole, so since the equator is halfway in between, it must get 12 hours of daylight.
The Sun at noon would be 66.5 degrees above the horizon at the equator. The Sun’s altitude at 23.5 degrees north is 90 degrees (directly overhead). The difference in latitude between the subsolar point (23.5 degrees north) and the equator (0 degrees) is 23.5, and 90-23.5=66.5.
The Sun at noon would be 23.5 degrees above the horizon. The Sun’s altitude at 23.5 degrees north is 90 degrees (directly overhead). The difference in latitude between the subsolar point (23.5 degrees north) and the North Pole (90 degrees north) is 66.5, and 90-66.5=23.5. At the North Pole on the June solstice, the Sun circles around all day 23.5 degrees above the horizon.
North
At the Tropic of Cancer. This will be the June solstice.
At the equator. This will be the equinox. For the Northern Hemisphere, it is the spring (vernal) equinox, since the subsolar point is moving north toward the Tropic of Cancer.
The Northern Hemisphere
23.5 degrees north
The Tropic of Cancer, the northern boundary of the tropics
12 hours; day length is always about 12 hours at the equator
24 hours; the Sun does not rise or set at the North Pole on the June solstice, it just circles around, 23.5 degrees above the horizon
0 hours; the South Pole has 24 hours of night on the June solstice, when the Sun does not rise above the horizon
The Antarctic Circle
The Arctic Circle
The Northern Hemisphere
66.5 degrees
Southward, toward the equator (reaching it in September), then to the Tropic of Capricorn (reaching it in December)
23.5 degrees south
The Tropic of Capricorn
12 hours; day length is always about 12 hours at the equator
0 hours; the North Pole has 24 hours of night on the December solstice, when the Sun does not rise above the horizon
24 hours; the Sun does not rise or set at the South Pole on the December solstice, it just circles around, 23.5 degrees above the horizon
The Arctic Circle
The Antarctic Circle
The Southern Hemisphere
66.5 degrees
Northward
0 degrees
The equator
12 hours
12 hours
90 degrees
Northward
The Northern Hemisphere
The Southern Hemisphere
Longer
Shorter
0 degrees
The equator
12 hours
12 hours
90 degrees
Southward
The Southern Hemisphere
The Northern Hemisphere
Shorter
Longer