Maybe someone can check my calculations please.
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Using
NASA Moon fact sheet
Moon distance from Earth (equator, km) 378,000 (NASA)
Apparent diameter (seconds of arc) 1896 (NASA)
Moon equator radius = 1738.1Km(NASA)
diameter= 2xradius = 17,381,000*2 = 34,762,000m
Apparent diameter (seconds of arc) 1896 = 1896/60 = 31.15 arc-minutes
I got this calculation from a Yahoo answers page.
A = angular size in arcminutes of an object (galaxy, nebula, etc.)
D = distance to object
S = linear size of object (in same units as D)
Then
S = A * D * 0.000291
This number, 0.000291, is the tangent of 1 arc-minute.
Plugging in our values...
S = 31.6 * 378,000,000m * 0.000291 = 34,759,368m diameter (near enough NASA's calc)
Using diameter from NASA above
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34762000/31.6 = 1,100,063m per arc-minute at the Moon equator
1100063/60 = 18,334m per arc-second = 18.3Km per arc-second at the equator
So, if I have got my calculation correct, it all depends on the effective resolution of the Earth-based telescope.
The
Palomar Observatory built in 1948 (1949 first light) has a 200 inch mirror.
Quote:
The reflective surface is adjusted in real-time, up to 2000 times a second, to correct for atmospheric distortions and refocus starlight into sharp images. PALM-3000 brings the optical power of the Hale Telescope closer to its diffraction limit by producing images typically 10–20 times sharper than seeing-limited instruments.
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Quote:
Astronomers measure the resolving power of a telescope in terms of degrees. Degrees are further divided into arcminutes and arcseconds.
1 degree = 60 arcminutes = 3600 arcseconds
The best telescopes on the ground can rarely see detail that is less than 1 arcsecond wide or differentiate between two stars that are less than 1 arcsecond apart in the sky.
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Quote:
Hubble can see detail down to less than 0.1 arcsecond across — more than 10 times clearer.
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From that page it says , the full moon is roughly 0.5 degrees or 1800 arcseconds across in a telescope view.
So, the theoretical Dawes limit is for
the Hale Telescope
116/508cm = 116/50800mm = 0.0023 arcseconds