Determining the expansion rate of the universe, the "Hubble constant," shapes our understanding of the cosmos, its age, and its fate.

New images show the rapidly rotating pulsar of the "Guitar Nebula" shooting out a gigantic cosmic plume of plasma, X-rays and ...

Brian Greene (Cosmic String Theory) and Astrophysicist Ethan Siegel have collaborated on a National Geographic coffee-table ...

What happens when the most advanced space telescope faces competition from the ground? The Extremely Large Telescope, built ...