If Planet 9 is real, this observatory has around a 70 to 80 percent chance of finding it, he estimates, adding that it's not a sure thing because there are so many uncertainties.

Feb. 18 marks the 95th anniversary of the discovery of our outermost planet-not-planet. Here's what to know about the short life of what was, for a single human lifetime, the solar system's ...

The chance of a planet forming in the outer reaches of the solar system – a hypothetical Planet Nine – could be as high as 40 per cent, but it would have been a rough start.

Pluto was demoted from a planet to a dwarf planet in 2006. So why is its status still so controversial today? When you purchase through links on our site, we may earn an affiliate commission.