The first person to observe these structures was the Third Earl of Rosse, who sketched them after using the Leviathan of Parsontown.
The first person to observe these structures was the Third Earl of Rosse, who sketched them after using the Leviathan of Parsontown. Depending on how well-defined they are, they can be classified as "grand design" or "flocculent". Vera Rubin examined numerous HII regions in these objects to conclude that they must be held by dark matter to explain their rotation. Although not Saturn's rings, density wave theory can be invoked to explain their rotation. These objects may be found on the (*) tines, but not the base, of Hubble's tuning fork diagram. They are classified as "barred" if a strip of stars lines their center. For 10 points, name this type of galaxy of which the Milky Way is an example.
The first person to observe these structures was the Third Earl of Rosse, who sketched them after using the Leviathan of Parsontown.
spiral galaxies [prompt on galaxies]