Since astronomers first measured the size of an extrasolar planet 17 years ago, they have struggled to answer the question: how did the largest planets get to be so large?
Deep Space
Deep Space
News
Earth-based telescope unlocks secrets of brightest galaxy in the universe
The Atacama Large Millimeter/submillimeter Array (ALMA) has got a closer look at the most luminous structure in the cosmos
Solar System
Video: Evolution of the Moon
Learn the violent and turbulent history of our largest natural satellite in this video.