Hubble revealed a universe of galaxies that existed beyond ours — but he couldn't have done it without a little help.

The Milky Way galaxy as seen from Earth. Image source: Yin/Adobe It’s a surprising discovery, the researchers say, because we previously believed that the halos of galaxies like the Milky Way ...

These “seeds” or stars were not full-fledged galaxies themselves, but instead the seeds that would later clump together to form our Milky Way galaxy, which would then grow as galaxies merged ...

In 1920, astronomers Harlow Shapley and Heber Curtis held a Great Debate. Shapley argued that the spiral nebulae were small and in the Milky Way, while Curtis took a more radical position that they ...