Electro astronomical atlas ... with explanatory notes, questions and answers (1874)
Spoor, J. W. (Joseph W.) · Albany, N.Y., Weed, Parsons and Company · leaf 30
of certain dark spots on itsdisc.Q. What is the axis of the Sun ?A. An imaginary line on which it revolves.Q. What is meant by the disc of a body ?A. The circular illuminated surface. 18 ELECTRO-ASTRONOMICAL ATLAS. Dark Spots on the Sun.Q. When and by whom were the dark spots onthe disc of the Sun… … Q. Do they always take the same direction overthe Suns disc? A. They do not. Sometimes they seem to moveacross it in straight lines ; at others, in curvedlines. Sometimes upward, as they cross fromeast to west; at others, they incline downward. Q. What causes these changes % A. They are owing to…
Astronomy
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