The desert city in southern Arizona is a sanctuary for stargazers—and now it's even easier for visitors to explore.

Though the planets are always “aligned,” seeing more than four in the sky is more uncommon. February’s lineup is a chance to ...

Scientists studying samples that NASA collected from the asteroid Bennu found a wide assortment of organic molecules that ...

Located less than 20 light years away, HD 20794d could potentially be one of the most Earth-like planets found so far, ...