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'Planet Y' theory hints at hidden Earth-size world lurking in the solar system — and it could be much closer to us than 'Planet Nine'

A new study has proposed the existence of Planet Y, an alternative Planet Nine candidate that is smaller and closer to Earth ...
MIT Technology Review

An Earthling’s guide to planet hunting

Earth’s turbulent atmosphere makes it hard to detect new planets from the ground. Astronomer Rebecca Jensen-Clem is working ...