Beyond Pluto: the hunt for our solar system's new ninth planet

Scientists think a planet larger than Earth lurks in the far reaches of the solar system. Now a new telescope could confirm their belief and change solar system science

You'd think that if you found the first evidence that a planet larger than the Earth was lurking unseen in the furthest reaches of our solar system, it would be a big moment. It would make you one of only a small handful of people in all of history to have discovered such a thing.

But for astronomer Scott Sheppard of the Carnegie Institution for Science in Washington DC, it was a much quieter affair. It wasn't like there was a eureka moment," he says. The evidence just built up slowly."