C Y N T H I A

"Cynthia" is olny a poetical manner, that dates back to greek mythology, to call the Moon.

There is not need to be astronomers in order to know the Moon; all people know it.   But , wich is its apparent diameter?            

As ameteur astronomer, I have had many times occasion to speak about the Moon, also with profanes. Common people, generally, do not know much about the Moon: sometimes they ask if the other face is known; or how are its "seas". 

But all believe to know  what is its apparent diameter! Protagora’s guilt, that said, the man is measure of all the things (Ántropos métron tón pantón).

Moreover, to measure the diameter of the Moon is an easy job. Try yourself: isn’t it perhaps so large as a plate?

Sure, Sardinians measure it in an other way: for they it is large as a sardinian Bread.
And not amaze if someone says that the Moon is large as a coin! he has all the right to choose its unit of measure! Unit that for the carter is obviously the wheel of the coach, and for the golf-player the golf-ball, with its craters!

But there are also well thinking people, that know that the Moon must be measured… in meters!
A such one said once to me that, according to him, the Moon was large three meters; others say one meter, others 20 cm., other again one centimeter.

But the more amazing thing of the enquiry that has amused me so much, is to state as the measures indicated from the greatest part of the consulted persons - that have been exactly one hundred, random-chosen among people of good cultural level - coincided in the interval of 20-30 cm.

No much amazing for profane, perhaps, but more amazing for the scientist, is the fact that to nobody came in mind to think that the Moon coult be measured neither in plates, nor in coins, wheels or meters, but only in degrees, arcminutes and arcseconds, since it is about angular dimensions.