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Is there a ninth planet on the outskirts of our solar system? © Caltech/R. Hurt (IPAC)

Is there a ninth planet on the outskirts of our solar system?

Published: 21st January, 2016 at 12:00
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Sorry Pluto, but we’re not quite ready to reinstate you to full planet status – there could be another more mysterious Planet 9 well beyond you.

We thought we knew our solar system. Are we wrong? A new study suggests that something massive and dark is lurking in the shadows of our very own backyard.


The study claims to have proven the existence of a frozen planet with a massive and slightly odd orbit hidden away in the pitch-black outskirts of the Solar System.

Importantly, researchers base their conclusion on mathematical modelling and computer simulations, not observation. "I couldn’t believe I'd never noticed this before. It's ridiculous," co-author Mike Brown of the California Institute of Technology told Scientific American.

If real, Planet 9 would be huge; 200 times further away from the Sun than Earth and at least 10 times more massive, with an orbit taking 20,000 years. In comparison, one of the biggest planets in the Solar System, Jupiter, has an orbit of 12 years. “For the first time in over 150 years, there is solid evidence that the Solar System's planetary census is incomplete," says co-author Konstantin Batygin of the California Institute of Technology in a press release.

Astronomers first became suspicious of the existence of a new planet when they observed that the most distant objects in the Kuiper belt, a dense collection of frozen debris and dwarf planets, swing in obscure orbits. Planet 9 would explain these unusual observations.

If the ninth planet does exist, our solar system will once again have nine planets. Ironically, it was Brown that stripped Pluto of its planet title back in 2006.

“All those people who are mad that Pluto is no longer a planet can be thrilled to know that there is a real planet out there still to be found," he says. So if you have a grudge, then this new planet-hunt may temper those feeling pent up inside you.

Though the Caltech researchers are quite confident of their results, we might want to hang on to the champagne bottle a bit longer. Other astronomers are intrigued but sceptical. “There is always a problem of uniqueness when it comes to this sort of thing,” says David Field, Emeritus professor at the department of Physics and Astronomy at Aarhus University. “Is the existence of a massive ninth planet in an odd orbit the only thing that could explain the observations? Are there other possible explanations?" he asks.

There is one thing would definitely put the debate to rest: let’s see it! The researchers from Caltech are eager for the world’s most powerful telescopes to point their lenses in the right direction. According to them, the Japanese Subaru Telescope in Hawaii should be able to glimpse the planet through the darkness.

Let the planet-hunt begin.


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