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Answers to Tutorial Questions The North Star, or Polaris (use the "Back" button on your browser after each question to get back to the Tutorial)
South. The subsolar point will not move north of the Tropic of Cancer. After the Solstice, the sun's direct rays will move towards 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.
Twelve 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.
a) the sun at noon would be 66 1/2 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 equator (0 degrees) is 23.5. 90-23.5=66.5
b) the sun at noon would be 23 1/2 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. 90-66.5=23.5. At the North Pole on the summer 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 towards the Tropic of Cancer.
Northern Hemisphere
23 1/2 degrees north
Tropic of Cancer, the northern boundary of the Tropics
twelve; daylength is always about 12 hours at the Equator
24; the sun does not rise or set at the North Pole on this day, it just circles around, 23 1/2 degrees above the horizon
zero; the South Pole has 24 hours of night on the June Solstice, the sun does not rise above the horizon
Antarctic
Arctic
Northern
66 1/2 degrees
southward, toward the Equator (reaching it in September), then to the Tropic of Capricorn (reaching it in December
23 1/2 degrees south
Tropic of Capricorn
12
zero
24
Arctic
Antarctic
Southern
66 1/2 degrees
northward
0 degrees
Equator
12 hours
12 hours
90 degrees
northward
longer
shorter
0 degrees
Equator
12
12
90 degrees
southwards
Southern
shorter
longer
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