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Question
How will you measure the diameter of the Moon using the parallax method?
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Solution
In order to determine the diameter of the moon, initially, a distance of the moon is calculated using the parallax method. Let D be the distance of the moon from the earth. Let d be the diameter of the moon. Let ∝ be the angular size of the angular diameter of the moon (ie) the angle subtended by d at the earth.
We have ∝ = `d/D`
d = ∝ D
The angle ∝ can be measured from the same location on the earth. When two diametrically opposite points of the moon are viewed through a telescope, the angle between the two directions gives the angular size or angular diameter. Since D is the known size or diameter d of the moon can be determined.
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