Learn how Pluto nearly kept its planet status in a proposed 12-planet Solar System as its demotion marks its 20th anniversary ...

Add Yahoo as a preferred source to see more of our stories on Google. Are planets in the solar system that are closer to the Sun older than the ones further away? – Gavriel, age 10, Paducah, Kentucky ...

A 24-year-old observatory assistant from the Midwest discovered Pluto. Clyde Tombaugh, born in 1906 in Streator, Illinois, ...

It is a question that feels like it should have a straightforward answer: how many planets are there in our solar system? Since Pluto was relegated back down to dwarf planet status, almost everyone ...