A new manual of the elements of astronomy, descriptive and mathematical .. (1868)
Kiddle, Henry, 1824-1891 · New York, Ivison, Phinney, Blakeman & co.; Chicago, S.C. Griggs & co. · leaf 81
CONSTANT DAT AND NIGHT. Qttestions.—c. What is the limit of constant day and night? 76 DAT AND NIGHT … S.Pole POLAB CIRCLES. of more than 24 hours duration. Hence, the limit of constant day isthe small circle round each pole, 23£° from it. These two parallelsare called polar circles. 113. The polar circles are twosmall circles, parallel to the equa-tor or equinoctial, and 23^° fromthe poles. The one…
Astronomy
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