Why was Pluto reclassified as a dwarf planet? One might think that it’s purely a matter of size. Mercury, the smallest of the ...

A new model that incorporates data gathered by the JWST could help scientists understand the composition and mass of objects ...

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

“New Horizons shattered a major paradigm of planetary science,” says Alan Stern, the mission’s principal investigator. “Pluto turns out to have as much complexity as Mars or Earth, so much so that I ...

People's profound connection with the Solar System led them to feel a remarkable sense of sympathy for Pluto when it was demoted to a dwarf planet in 2006. But why was it reclassified, and why did ...

Forbes contributors publish independent expert analyses and insights. Jamie Carter is an award-winning reporter who covers the night sky.

A decades-old cosmic mystery may finally be solved. Scientists now suspect that the strange X-ray glow from a distant white ...

Today NASA said that the Dawn spacecraft has fallen out of contact with Earth, presumably because it’s run out of the thruster… Read More The once-mysterious bright spots shining on the surface of the ...

That's not just because it's too far away. In 2006, the International Astronomical Union (IAS) reclassified Pluto as a dwarf planet. That decision came several years after discovering the Kuiper ...

Arizona in 1930 and was considered our ninth planet until 2006. The International Astronomical Union reclassified Pluto as a dwarf planet because it does not clear its orbit of other debris.