"The data from the termination shock encounter will be a treasure trove for space physicists worldwide who are eager to ...

An amateur astronomer discovered Pluto 95 years ago today. The former planet will complete an orbit in another 153 years.

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

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

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

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

Today: On Feb. 18, 1930, Clyde Tombaugh discovered Pluto, at that time classified as the ninth planet.

Why is Pluto no longer a planet? Discover the real reason behind Pluto’s reclassification as a dwarf planet and the science that led to this change.

Pluto isn't alone—it's part of the Kuiper Belt with possibly hundreds of other planet-sized objects. Because Pluto hasn't ...

According to a recent YouGov poll, 35% of Americans think Pluto is not a planet. But they are all wrong—kind of. To get to ...

The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

Eris is three times more distant than Pluto. And its relationship to Pluto — a world demoted since 2006 from the solar system’s ninth planet to a lowly dwarf planet, in large part due to the ...