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 ...

Frigid water helped paint Mars red and may have shaped a vast coastline, two new studies into the planet’s history reveal. Scientists have detected a possible ancient beach in Mars’ northern ...

Six planets will align before dawn on June 3 in a planetary parade, but only two will be visible to the naked eye. Mercury, Jupiter, Uranus and Neptune will likely be obscured by the rising sun or ...

Pluto was reclassified as a dwarf planet in 2006, but new discoveries and fresh debate are reigniting calls to restore its planet status. Learn why Pluto lost its title, what scientists discovered ...

Forbes contributors publish independent expert analyses and insights. Leslie Katz covers the intersection of culture, science and tech. A yellowish-orange glow bathes Phainoterra, a planet of dramatic ...

“Mars, can you please clean up your Legos?” “Jupiter, finish your peas.” “Don’t pull the cat’s tail, Mercury!” ...

Unfortunately for science fiction fans, desert worlds outside our solar system are unlikely to host life, according to new research from the University of Washington. Scientists show that an ...

Astronomers spotted a potential Earth-size rocky world orbiting a white dwarf, suggesting a future in which our planet outlives its star. By Jonathan O’Callaghan In six billion years the sun will ...

The results of the planet’s first annual physical—a complete health check—are in, and they are alarming. We are deep into the yellow danger zone and moving rapidly towards the red high-risk zone, ...

Even at a glance, the planets in our solar system are wildly diverse. Huge and small, airless and densely packed with ...