Mercury is the smallest planet in our solar system. Explore its size, extreme temperatures, core structure, and comparison with Pluto.

By Will Dunham WASHINGTON, Feb 14 (Reuters) - Astronomers have observed a planetary system that challenges current planet formation theories, with a rocky planet that formed beyond the orbits of its ...

The biggest planet in the Solar System. And the smallest star in the known Universe. Today, they are on a collision course.

The system, observed using the European Space Agency's Cheops space telescope, consists of four planets — two rocky and two ...

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

If a gas giant planet is big enough to ignite deuterium fusion, it becomes a brown dwarf instead of a planet. But this definition is incomplete and does not tell us how gas giants form or what ...

Key takeawaysIf a gas giant planet is big enough to ignite deuterium fusion, it becomes a brown dwarf instead of a planet.

A distant star system with four super-sized gas giants has revealed a surprise. Thanks to JWST’s powerful vision, astronomers detected sulfur in their atmospheres — a chemical clue that they formed ...

Things Boomers learned in school that turned out to be wrong Baby Boomers sat through countless lessons that seemed ironclad at the time. Teachers confidently taught ...

Learn about HD 137010 b, a cold Earth‑sized planet candidate that sits near the outer edge of its star’s habitable zone.

Gas giants are enormous planets made primarily of hydrogen and helium. They may contain dense central cores, but unlike Earth, they do not have solid ...

Newly reprocessed radio observations are transforming the quiet reputations of nearby dwarf stars. What once looked like background hiss now resolves into violent, short‑lived outbursts that can dwarf ...