The First Moon Map, and Not By Galileo
sergio80 writes in with a timely piece of history in this the International Year of Astronomy, celebrating the 400th anniversary of the invention of the telescope. "Galileo Galilei is often credited with being the first person to look through a telescope and make drawings of the celestial objects he observed. While the Italian indeed was a pioneer in this realm, he was not the first..." That honor belongs to Thomas Harriot, an Englishman, who bought his first "Dutch trunke" (i.e. telescope) shortly after its invention in the Netherlands and made a sketch of the moon as seen through it in July of 1609.
"if you took your own photo of them, you would have the copyright to it"
Wrong (In the US).
In the US we don't give copyright for simply making a faithful reproduction of anything. You didn't add any new creative element by taking a photograph of a piece of paper. This is why Google does not hold a copyright on the scans of public domain works. (but they do limit their use based on Contracts/TOS, which is fine, you can sign away your rights in a contract)
For the court case which spells this out see: http://en.wikipedia.org/wiki/Bridgeman_Art_Library_v._Corel_Corp.
Now, in the UK, what you said is probably correct. They are, in my opinion, wrongly assigning copyright to people based on "sweat of the brow" work, not creativity.