Olmsted, Denison, 1791-1859. [from old catalog] · New York, R. B. Collins · leaf 85
g an extent of 50,000 miles in diameter. They aresometimes even visible to the naked eye, when the sunis viewed through colored glass, or, when near the hori-zon, it is seen through light clouds or vapours. When itis recollected that 1 of the solar disk implies an extentof 400 miles, it is evident… … 105. Solar spots.—Are they constant or variable in numberand appearance ? How many are sometimes seen on the sunsdisk at once ? Are they usually large or small 1 How manymiles in diameter are the largest 1 Describe a spot. Whatchanges occur in the nucleus ? What is the umbra ? In whatpart of the…
Astronomy
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