Milky way structure

The spiral structure of the Milky Way was deduced using radio wave emissions of ionized hydrogen. This discovery identified our galaxy as having a spiral structure, similar to the Andromeda Galaxy.
William Wilson Morgan United States 1951
Milky way structure

The spiral structure of the Milky Way was deduced using radio wave emissions of ionized hydrogen. This discovery identified our galaxy as having a spiral structure, similar to the Andromeda Galaxy.