~ Neptune is a giant gas planet which is most likely made up of various "ices" and rock.
~ Neptune has been visited by only one spacecraft, Voyager 2 on Aug 25 1989. Almost everything we know about Neptune comes from this one visit.
~ Depending on how far along Pluto is in its orbit (path around the Sun), Neptune can be either the eighth or ninth planet. Pluto's orbit is kind of wacky, and it sometimes crosses in front of Neptune. When Pluto does this, Neptune is behind Pluto - hence, it is the ninth planet for a short time.
~ Neptune has 8 known moons; 7 small ones and a large moon called "Triton."