How many astronomical units (A.U.) make 1 parsec? Consider a sunlike star at a distance of 2 parsecs. When it is seen through
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answered 5 days ago by Mohit singh (24k points)
selected 5 days ago by Faiz Ahmad
(a) By definition of parsec
(b) At 1 A.U. distance, sun is (1/2°) in diameter. Therefore, at 1 parsec, star is (1/2/2 x 105) degree in diameter = 15 × 10-5 arcmin.
With 100 magnification, it should look 15 × 10-3 arcmin. However, due to atmospheric fluctuations, it will still look of about 1 arcmin. It can’t be magnified using telescope.
At 1 A.U. sun is seen as 1/2 degree in diameter, and mars will be seen as 1/1600 degree in diameter.
At 1/2 A.U, mars will be seen as 1/800 degree in diameter. With 100 magnification mars will be seen as 1/8 degree 60/8 = 7.5 = arcmin.
This is larger than resolution limit due to atmospheric fluctuations. Hence, it looks magnified.