A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Select the first letter of the word from the list above to jump to appropriate section of the glossary. If the term you are looking for starts with a digit or symbol, choose the '#' link. - N - nebula Areas of celestial dust and gas, the birth places of new stars. A few are visible by naked eye. They may be seen because they are backlit by neighboring stars. Neolithic Late Stone Age, roughly 12,000-2000 years B.C.E. In many areas of the world, this time is associated with the development of agriculture. Records in stone referring to astronomical alignments have been dated to this time. Neptune Discovered in 1846, this is the eighth planet out from the Sun, and is one of the Jovian planets. Newgrange Located near the Boyne River, Ireland, it is a passage grave formed by a huge mound and accompanying stonework, built with astronomical significance. Constructed around 3200 B.C., it is the oldest known astronomically-oriented site in the world. North Star Definition. Back to Top