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 ...

Euclid telescope has located a rare hoop of light called an "Einstein ring" in a nearby elliptical galaxy. Though the galaxy has been on humans' radar for 140 years, its halo is new—and it has a lot ...

Henrietta Swan Leavitt, an astronomer ahead of her time, discovered the relationship between a star’s brightness and its fluctuation period. This breakthrough allowed Edwin Hubble to measure galaxy ...