There may be another world lurking between the orbital lines of our solar system. Astronomers in Japan have published their theory of an “Earth-like planet,” dubbed Planet Nine, that’s ...

"The solar system’s distant reaches exhibit a wealth of anomalous dynamical structure, hinting at the presence of a yet-undetected, massive trans-Neptunian body — Planet 9," the study abstract ...

Almost 20 years after Pluto was infamously downgraded from its status as a planet, scientists now believe they have discovered a new planet in our solar system.

The quest to find hidden worlds. Searching for planets lurking in the frigid edges of our solar system is not a new concept. The so-called Planet Nine, a world 10 times more massive than Earth, is ...

There have been questions about a mysterious ninth planet in our solar system for nearly a decade. Pluto was unseated as number nine in 2006. Now, a group of international researchers say they may ...

There have been questions about a mysterious ninth planet in our solar system for nearly a decade. Pluto was unseated as number nine in 2006.

From the slate gray of Mercury to the ruddy brown of Pluto, the worlds in our solar system are a veritable rainbow of colors. But what makes them all look so different?

While we have a precise (and probably accurate) age for the solar system, we do not have precise ages for each planet. Skip to content Introducing the all-new Astronomy.com Forum!

About 71% of our planet's surface is covered in water, according to the U.S. Geological Survey, and Earth's atmosphere protects the planet from solar radiation. Earth is the only planet not named ...

If you could go back 4.6 billion years, you would see a time before our solar system even existed. But space wouldn’t be empty—you would encounter a cloud of gas and dust in place of our sun ...