Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously unknown world may be lurking in the outer reaches of the solar system. The ...

An exoplanetary system about 116 light-years from Earth could flip the script on how planets form, according to researchers who discovered it using telescopes from NASA and the European Space Agency, ...

Learn how Pluto nearly kept its planet status in a proposed 12-planet Solar System as its demotion marks its 20th anniversary. Eight days before Pluto lost its planetary status, it appeared ready to ...

Our definition of a planet has changed over the years — causing a bit of confusion. | Credit: wasan prunglampoo/Getty Images Over the past 250 years, the number of "planets" in our solar system has ...

Add Yahoo as a preferred source to see more of our stories on Google. An illustration of our solar system showing the planets far closer together than they are in reality in order to represent the all ...

James is a published author with multiple pop-history and science books to his name. He specializes in history, space, strange science, and anything out of the ordinary.View full profile James is a ...

Rocky planets like our Earth may be far more common than previously thought, according to new research published in the journal Science Advances. It suggests that when our solar system formed, a ...

Ancient iron meteorites reveal that some of the Solar System’s first solid bodies were built mostly from tiny heat-forged rock beads called chondrules, while water-rich dust was largely excluded. The ...

As an astrophysicist, my world revolves around the wonders of space and the mysteries of the universe. This means I can be a tough critic of science fiction books and films that explore these topics.

Over the past 250 years, the number of "planets" in our solar system has ranged from six to nine — and, briefly, even 11 — depending on what astronomers knew at the time and how they defined a planet.

Even at a glance, the planets in our solar system are wildly diverse. Huge and small, airless and densely packed with atmosphere, they have a wide range of characteristics distinguishing them. But if ...