A fresh study of the Kuiper Belt’s structure has revived that far-out question, pointing to a possible Earth-sized ...

On August 24, 2006, our solar system lost a planet. It wasn't by cataclysmic destruction, but rather by the vote of the International Astronomical Union, which declared that Pluto, considered the ...

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 ...

Mike Brown is convinced that beyond Neptune, at the far reaches of our solar system, there's an unseen giant planet. "This is the 5th largest planet in our solar system, lurking out there, waiting to ...

For over a century, astronomers have wondered if there’s an extra planet in our Solar System that we haven’t been able to detect yet. It seems like we get another “Planet Nine” candidate — formerly ...

As telescopes have become more powerful, it’s turned out our solar system is not the only game in town: There are millions of ...

Carbon dioxide has been detected on a planet outside our solar system for the first time. The gas has been observed directly by the James Webb Space Telescope on four exoplanets, all belonging to the ...

A tiny meteorite is rewriting what scientists thought they knew about the origins of our solar system. New evidence found in shavings from a meteorite known as Northwest Africa 12264 — a 50-gram (1.8 ...

Every year, Earth follows a familiar pattern of seasonal changes: As summer rolls around in the Northern Hemisphere, winter creeps in in the Southern Hemisphere, and vice versa. But do other planets ...

Astronomers have discovered that aging stars may be devouring their closest giant planets as they swell into red giants.