A hundred years ago, astronomer Edwin Hubble dramatically expanded the size of the known universe. At a meeting of the ...

Shapley argued that the spiral nebulae were small and in the Milky Way, while Curtis took a more radical position that they were independent galaxies, extremely large and distant. At the time ...

In the century since Hubble’s pioneering work, astronomers like me have learned that the universe is vast and contains trillions of galaxies. Nature of the nebulae In 1610, astronomer Galileo ...