Ghost Planet Nine
I was quite eager to write about the ghost planet 9 in my mysterious and strange planet series but with recent news, I'll touch on a little now.
We've known about a 9th planet in our solar system, for quite some time. Unfortunately when I mention the 9th planet I don't mean Pluto.
How do we know there's a 9th planet? Our solar system has a tilted orbit which is being affected by a gravitational pull assumed to be caused by Planet 9.
The latest update is astronomers have found another indirect link; an object called 2015BP. 2015BP (Caju) might be a dwarf planet but has an abnormal orbit, that couldn't be explained until they added Planet nine into the mix. With more research and time hopefully we'll find Planet 9 soon.
Source
https://www.slashgear.com/dwarf-planets-orbit-could-point-to-existence-of-planet-nine-18531198/