>>>I'm certainly not an expert, but I don't know how they know what something that far aways is in the first place. All the pics of Pluto I ever saw is just a around white spot.
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>>>I saw a documentry of our solar system once and they said that the distance between the sun and Pluto would be like someone holding a regular 100 watts light bulb and another person holding a B-B pellet some 10 miles away.
>>>It blew my mind....:-)
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>>The distance Sun-Pluto is around 40 AU (40 Astronomical Units, i.e., 40 times the distance Sun-Earth). That means that for any hypothetical inhabitant or visitor of Pluto, the Sun would seem 1/1600 as bright as for an inhabitant on Earth. For a start, that means it's really cold over there, apart from being dark. Also, spacecraft can most likely no longer use solar energy, and must instead use nuclear reactors.
>
>Thus the sun would seem ~40Xs smaller from Pluto. That would be like us looking at a quarter from 100 meters away.

Yes, "smaller" referring to the apparent size, in degrees etc. From here, the Sun has an apparent diameter of about 30 minutes (1 degree = 60 minutes); from Pluto, it would be less than a minute. I think the Sun would seem more like a bright star (a very bright one, much brighter than Venus looks to us) than like what we think of as "The Sun".

While it is difficult (and risky) to look at the Sun directly, the Moon has about the same apparent diameter - just to give you an idea of the apparent diameter.

About the dime, yes, that works out - since the sine (or tangent - doesn't make much difference at small angles) of 1/80 degree is about 0.00022, at 100 meters it would require an object of about 2.2 cm. to look this size. Yes, it seems that would be the typical size of a coin - although I am not used to using dimes. The dime, according to Wikipedia, is slightly smaller - almost 1.8 cm.