This weekend, six planets are set to share the sky in a rare “planet parade,” giving stargazers a short but magical window to ...

It was almost 100 years ago that Clyde W. Tombaugh discovered Pluto. That was the last planet found until 1992, when humans found another one. But this new planet wasn't in our solar system—it was ...

This artistic photo compilation compares the size of Planet Nine (right) to Earth (left). Dr. Konstantin Batygin, professor of Planetary Science at Caltech, made a joke that turned out to be true. In ...

All planets are made of gas, ice, rock and metal, and models of how planets form usually assume that these materials don't react chemically with each other. But what if some of them do? UCLA and ...

Gas giants are large planets mostly composed of helium and/or hydrogen. Although these planets have dense cores, they don't ...

It wasn’t all that many years ago that you could go to a major astronomy meeting and hear the latest news about galaxies and supernovas and quasars and the Big Bang — but nothing at all about planets ...

For decades, our solar system was thought to have nine planets, with Pluto considered the smallest and farthest. But in 2006, Pluto was officially reclassified as a dwarf planet by the International ...