PLANET Nine, aka Planet X, has perplexed astronomers since it was first proposed in 2014. So what exactly is Planet X and is Planet 9 in our solar system?
Planet Nine discovery: What is Planet 9? Is Planet X in our solar system?
PLANET Nine, aka Planet X, has perplexed astronomers since it was first proposed in 2014. So what exactly is Planet X and is Planet 9 in our solar system?
