Astronomers at the California Institute of Technology announced Wednesday that they've discovered gravitational evidence of a ninth, previously unknown planet in our solar system. The planet, dubbed "Planet Nine," is believed to be a massive, icy planet between five and 10 times the size of Earth that lies far beyond Pluto's orbit at the edge of our solar system.
"There have only been two true planets discovered since ancient times, and this would be a third," one researcher said. Researchers have telescopes stationed on at least two continents to try to catch their first direct glimpse of Planet Nine. Becca Stanek
The Week
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