The discovery of a tiny speck of stardust, the remnant of a long-gone star, could hold clues about our solar system’s birth, say UA scientists involved in the discovery. Found inside a meteorite ...

LONDON — 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 ...

Planet Y is the latest in a series of hypothetical solar system planets that scientists have proposed in recent years, all with slightly different characteristics but collectively believed to be ...