| 摘要 |
Teaching devices for illustrating the relationship between the earth and the sun should be informative and applicable anywhere on earth at any time of the year. The teaching device of the present invention includes a disc pivotally mounted on a baseplate for illustrating the earth's angular position relative to the sun throughout the year. The disc has a representation of the earth thereon with parallel lines of latitude and arcuate longitudinal time lines. The base plate includes a first set of indicia representing the days and months of a year, a second set of indicia representing the sun's rays, and a day/night line, which can be used when determining the time of sunrise at any location on earth.
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