Early observations of the planets revealed worlds far different from Earth, demonstrating that the universe was far more ...

A team of astronomers from Taiwan has uncovered promising evidence suggesting the existence of Planet 9, a hypothesized planet beyond Pluto in the far reaches of our Solar System. This new potential ...

Pluto was demoted from a planet to a dwarf planet in 2006. So why is its status still so controversial today? ... It must have enough mass to draw itself into a round shape.

Astronomers had found Planet X, now called Pluto (after the Roman god of the underworld). However, after analyzing the new planet’s orbit, astronomers declared Pluto had too little mass to ...

An impact early in Pluto’s history would have created a mass deficit, causing Sputnik Planitia to slowly migrate toward the dwarf planet’s north pole over time while the planet was still forming.

Because then, as you decrease the mass of the sun, the mass ratio of Pluto, whatever you want, to the sun becomes a huge number. Then things, even not very massive things start acting like planets.

We’ve learned that the most common mass/size combination for a planet is intermediate between Venus/Earth and Uranus/Neptune: ... The 8 planets of the Solar System are all in; Pluto is clearly out.

Group of scientists published 5-year study arguing the current definition of planet was rushed, and should include Pluto, along with 100 other celestial bodies.

A telescope has discovered a new world on the edge of the Milky Way – potentially confirming the ‘Planet X’ theory. Beyond ...

I f Pluto’s looking for someone — or something — to blame for being drummed out of the planetary corps back in 2006, it need look no further than Eris. The solar system’s ninth planet had ...

Then another “planet” was discovered. On March 28, 1802, German physician and astronomer Heinrich Olbers discovered Pallas; this was rapidly followed by Juno in 1804 and Vesta in 1807.