Feb. 18 marks the 95th anniversary of the discovery of our outermost planet-not-planet. Here's what to know about the short ...

On the 95th anniversary of its discovery, Pluto remains one of the most beloved and enigmatic worlds in our solar system, ...

Trans-Neptunian objects (TNOs) are icy bodies that vary widely in size, from large dwarf planets like Pluto and Eris—each ...

Saturn, Venus, Neptune, Uranus, Jupiter, Mars and Mercury will be visible in an uncommon planetary alignment this month.

Clyde Tombaugh discovered Pluto in 1930 at Lowell Observatory in Flagstaff. Here's how Pluto won - and lost - its planetary status.

“New Horizons shattered a major paradigm of planetary science,” says Alan Stern, the mission’s principal investigator. “Pluto ...

Astronomers use planetary alignment to describe the phenomenon when planets gather closely on one side of the Sun at the same ...

Planet demographics reveal a puzzling lack of worlds in a certain size range throughout the galaxy F or centuries our solar system was the only planetary system known to humans. We had no proof other ...

The planet Neptune wobbled in its orbit around the Sun. That could only mean one thing, astronomers said: There was a ninth planet out there, somewhere, lurking in the fringes of the solar system.

NASA has just made a groundbreaking discovery—a new planet beyond Neptune that wasn’t there before! This mysterious find ...

A new study examines how much material from the closest star system to Earth will end up in orbit around the Sun, and how ...

Scientists at NASA for the first time have been able to observe the make up of Pluto and other small and icy celestial bodies ...