Good Morning, I've got a doubt originated from a statement of Berkeley Physics Course, Vol.1 - Mechanics, pg. 107, where in a footnote we read, "The systems are called galaxies, that one which contains our own sun is known as the Galaxy. The Milky Way is part of our galaxy". I've always considered the Milky Way as our entire galaxy, and have never heard about "The Galaxy". Could you please explain me if that is either an old classification (the book is from the 1960's) or if I'm not well informed about the matter? Thank you! Cheers, Luke.