Hunt for elusive ‘Planet Nine' at edge of solar system offers surprise

South China Morning Post

5 days ago

It is an evocative idea that has long bedevilled scientists: a huge and mysterious planet is lurking in the darkness at the edge of our solar system, evading all our efforts to spot it.
Some astronomers say the strange, clustered orbits of icy rocks beyond Neptune indicate that something big is out there, which they have dubbed Planet Nine.
Now, a US-based trio hunting this elusive world has instead stumbled on what appears to be a new dwarf planet in the solar system's outer reaches.
And the existence of this new kid on the block could challenge the Planet Nine theory, the researchers have calculated.
Named 2017 OF201, the new object is roughly 700km (430 miles) across according to a preprint study, which has not been peer-reviewed, published online last week.
That makes it three times smaller than Pluto.