In 2006, the International Astronomical Union (IAU) voted on the definition of a planet. Famously, Pluto no longer met the criteria and was demoted to a dwarf planet. Things have been a bit of a mess ...

For many people, the definition of a planet was only made clear in 2006, when the spunky world Pluto was demoted from a planet to a dwarf planet. Now, a team of astronomers is pushing for “planet” ...

On January 5, 2005, astronomers at NASA discovered Eris, the second-largest dwarf planet in the solar system. Eris is just slightly smaller than Pluto, and it orbits the sun about three times farther ...

Will Pluto have the last laugh? A group of NASA scientists hopes so. A group of members of the New Horizons mission to Pluto are making the case to redefine what constitutes as a planet to be more ...

Pluto, once considered the ninth planet, was reclassified as a dwarf planet in 2006 because it shares its orbital path with other objects. Despite its demotion, this distant world continues to ...

Mercury is sparing us from any retrograde drama over the coming month, but October still has some retrograde energy in store. Jupiter retrograde begins on Oct. 9, and then two days later, Pluto ...

Decades-old pictures of Pluto’s heart are breaking the Internet again. University of Oxford's Dr Carly Howett explains the science behind the New Horizons mission and that famous 5-billion-kilometre ...