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

A mysterious object has caused a long-lasting and extreme dimming of a distant star, but is this object a 'failed star' brown dwarf, or an exceptionally massive super-Jupiter exoplanet?

Astronomers have discovered a planetary system that appears to flip one of astronomy's most reliable rules on its head.

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

Far beyond Neptune lies a vast and unsettling frontier filled with dwarf planets, ancient ice worlds, collapsing atmospheres, strange moons, and orbits that take thousands of years to complete. From ...

Discover the Kuiper Belt: a frozen ring of dwarf planets and trillions of icy bodies, currently being explored by NASA's New Horizons mission.

Is a “temporary second moon” really going to orbit the Earth? That’s the claim made in a number of viral social media posts that feature spectacular AI-generated visuals. Spoiler: contrary to these ...

As next-generation telescopes map this outer frontier, astronomers are bracing for discoveries that could reveal hidden planets, strange structures, and clues to the solar system’s chaotic youth.

Pluto and its largest moon Charon have a rare tidal locking relationship, constantly showing the same faces to each other.

Things are much bigger outside the solar system.

But unlike Jupiter, Venus does have phases, going from not illuminated at all (when it is between the Earth and the Sun) to ...