
On the hunt for a mystery planet - micaeloliveira
http://www.nature.com/news/on-the-hunt-for-a-mystery-planet-1.19565?WT.mc_id=TWT_NatureNews
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n0us
The idea of another large planet in our solar system is exciting but could
someone more knowledgable clear something up? Do astronomers expect that there
might be more large undiscovered planets or is the prediction of this most
recent one considered a fluke?

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NZGumboot
I'm not an astronomer, so don't take this as gospel, but I believe that large
undiscovered planets are expected to be rare. Mainly because they would have
had to form in the inner solar system (where all the matter was) and then
somehow flung into the outer reaches of the solar system (perhaps via a major
collision).

Relevant XKCD: [https://xkcd.com/1633/](https://xkcd.com/1633/)

