As astronomers continue discovering unusual worlds beyond our solar system, many say the question that divided scientists in ...

On the 20th anniversary of Pluto’s infamous demotion, Mike “Pluto Killer” Brown explains why any reversal of that decision would be driven more by nostalgia than science ...

Pluto is no longer a planet, but why did it lose that title? The change came in 2006 from the International Astronomical Union, which wanted a clear definition of what a planet actually is. Before ...

Pluto lost its planethood for a very specific reason. Whether or not that’s a good reason depends on who you ask.

Since it was stripped of planetary status, Pluto’s defenders have been fighting the decision – and they’re only getting more passionate ...

Pluto's demoted status as a dwarf planet turns 20 years old today and isn't even a chink in its armour when it comes to its astrological impact.

Add Yahoo as a preferred source to see more of our stories on Google. NASA chief Jared Isaacman has doubled down on his stance that Pluto is without a doubt a planet. For two decades, controversy has ...

Those who supported Pluto’s demotion included Neil DeGrasse Tyson ...

A 24-year-old observatory assistant from the Midwest discovered Pluto. Clyde Tombaugh, born in 1906 in Streator, Illinois, grew up fascinated with the solar system. A self-taught astronomer, he built ...

For generations of schoolchildren, the solar system had nine planets. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, ...

The discovery of the Kuiper Belt revealed thousands of icy objects near Pluto, challenging its status as a planet. After the discovery of Eris, astronomers formally redefined “planet” in 2006, leading ...