The International Astronomical Union defines a planet as a celestial body that orbits the sun, is massive enough that gravity has forced it into a spherical shape, and has cleared away other objects ...

If the object really is Planet Nine, it would be larger than Neptune and exist 700 times further from the sun than Earth. When you purchase through links on our site, we may earn an affiliate ...

For almost a decade, astronomers have been searching for a ninth planet in the solar system. Recently, new evidence of another possible planet, dubbed Planet Y, was uncovered, and it could be around ...

A team of scientists at the Institute for Advanced Study School of Natural Sciences in Princeton, New Jersey, might have found a new dwarf planet, potentially leading to more evidence of a theoretical ...

The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper’s authors have dubbed ...

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Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. Our solar system ...

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 ...