The sun is a sphere. It has a diameter of 32 miles and is located approximately 3000 miles above the surface of the earth.
Spotlight effect
The Sun's area of light is limited to a circular area of light upon the earth much like the light of a lighthouse is limited to a finite circular area around it. The rotating light on a lighthouse does not propagate infinitely into the distance. This means that only certain portions of the Earth are lightened at a time. It also describes how night and day arise on the Flat Earth. The apparent view of rising and setting are caused by perspective, just as a flock of birds overhead will descend into the horizon as it flies into the distance.
Rendered picture of the Sun in relation to the Earth
Not to scale: http://theflatearthsociety.org/forum/index.php?topic=1264.0
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Temperature Variations of sunlight
Magnification of the Sun at Sunset, or how the sun maintains its size throughout the day.
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