I wasn't sure what category to put this in!
I have read the origin of the whole myth; so I'm sure it doesn't exist.
It started with two scientists discussing the apparent regularity of mass extinction events. Forgive me, but I don't remember which scientists they were.
Scientist A points out to Scientist B that Earth's mass extinctions have happened approximately every 26,000,000 years.
B suggests that the events were possibly caused by similar events.
A bets that B cannot offer an explanation for regular extinctions caused by asteroids, since we know that one caused the K-T mass extinction.
B throws out that a large planet with an irregular orbit which passes through the inner solar system every 26 million years, could pull asteroids out of their orbit in the asteroid belt and trigger impacts with earth.
So basically, the concept of Nibiru was based on a hypothetical scenario with absolutely no evidence.
Well, the whole "Planet Nibiru is going to fly into the inner Solar System and wreak havoc" is nonsense. There is some thought that the orbits of some Kuiper Belt objects can best be explained by an as yet undiscovered Neptune sized planet that orbits about 20 times further from the Sun than Neptune. Still, until astronomers spot it, it's just speculation.
Calculations of the orbits of some Kuiper Belt objects suggests that it does exist. There's only 0.0007% chance that the orbits of these Kuiper Belt objects formed by "random".
We simply have not found it.
SpaceTime YouTube science news discusses this and its relation to the history of finding Pluto. He also mentions why Pluto's status was downgraded from planet to planetoid.
If we don't save this planet, we don't deserve another.
@ScienceBiker Also true.
Idk about Planet-X, or if we will find it?
@Gwendolyn2018 oh shit, it's the end of the world, again.