Great Mysteries of Outer Space: Dark Energy and the Hubble Tension
Around 13.7 billion years ago, something collapsed. It fell outward into the nothingness that stretched in every direction, ...
One large Milky Way galaxy or many galaxies? 100 years ago, a young Edwin Hubble settled astronomy’s ‘Great Debate.’
In 1920, astronomers Harlow Shapley and Heber Curtis held a Great Debate. Shapley argued that the spiral nebulae were small ...