Crib Sheet: Everything We Know About The New 'Planet Nine'

Scientists may have just discovered a ninth planet in our solar system. We're not talking no "dwarf" here neither, but a bona fide planet up to 10 times larger than Earth. If the evidence checks out, it will be the first planet discovered in our solar system in more than 80 years. (170 if you don't count Pluto.) We consulted with an expert to bring you the facts for those watercooler chats in the office.

Planet picture from Shutterstock

It's an exciting time to be an astronomy buff. In the past few months, we've been treated to spectacular photos of Pluto, confirmed the presence of water on Mars and discovered a new, Earth-like planet that could potentially harbour life. Now, fresh evidence has been uncovered that points to the existence of a distant ninth planet within our solar system. Telescopes around the globe are currently scrambling to capture the first image of this mysterious celestial body.

We spoke to Dr John Morgan, Research Fellow at Curtin University's Department of Physics and Astronomy about this exciting discovery. Here are all the facts so far.

The Discovery

Yesterday, two researchers at Caltech in the US divulged evidence for a large planet well beyond the orbit of Neptune. At the time of writing, this planet has not been detected directly. Rather, the evidence is based on the gravitational behaviour of objects in the outer reaches of the solar system, which strongly point to the presence of a large celestial body.

"There's something rather strange about the way the orbits of [these] objects tend to line up," Dr Morgan explained to Lifehacker. "The researchers have managed to come up with an explanation: it turns out this alignment can be explained by the presence of a large planet.

"Once the researchers modelled the effects that a planet like this would have, they found that it seemed to clear up a few other mysteries as well. This makes the "Planet 9" hypothesis quite convincing."

In an interesting twist of fate, one of the authors of the new study is none other than Michael E. Brown: the same astronomer who was instrumental in "killing" Pluto by demoting its status to a dwarf planet.

What kind of planet is it?

The maths behind the discovery points to a planet with a mass between five and 10 times greater than Earth. The rest is mostly conjecture.

"The only thing that this study can tell us is the planet's mass," Dr Morgan said. "This is interesting as it's somewhere in between the mass of rocky planets such as the Earth, and gas giants such as Jupiter. So is it rocky, gas giant, or something in between?"

According to the researchers, Planet Nine is most likely an ice giant core, with a diameter approximately twice that of Earth.

Direct evidence may already exist

According to Dr Morgan, there may already be an image of the planet out there, waiting to be analysed.

"This research has given us a rough idea of where in the sky to look, so no doubt many astronomers will be double-checking their archives for evidence of Planet 9."

The obligatory 'aliens' question

Yeah, nah. Regardless of the surface type, it's highly unlikely that this planet's atmosphere could support life of any kind. Naturally, the planet would be extremely cold, being situated in the most remote reaches of our solar system. We're talking at least 200 times farther from the sun than the Earth.

Why has it taken so long to discover?

Here's what Dr Morgan had to say on this topic:

"It may sound embarrassing that there's a planet bigger than the Earth that we've failed to spot, but there's two things to bear in mind. First of all, the planet is very far away from the Sun. Planets don't produce their own light, they can only reflect the light of the Sun, and at the distance of this planet the Sun is 40,000 times less bright than on Earth. Secondly, it's very far from Earth making it even more difficult to spot."

So what does this mean for science?

If Planet Nine is the real McCoy, it could provide astronomers with fresh insights into the birth of our solar system. It will also bring our planetary system more in line with others in the galaxy whose celestial bodies more closely resemble Planet Nine. Plus, a lot of high school text books will need to be updated.


    I think we should petition for Pluto to be classified as a planet again, thus making this new one the tenth planet. Then all us fat, old geeks could yell out:
    “Where are we going?”
    “Planet Ten!”
    “Real soon!”

      Also, we could name it "Planet X" and it would make sense numerically.

      pluto doesn't need to be classed as a planet. it's already interesting enough as a dwarf binary system.

    Can we wind back the hyperbole until or if they actually find it please

    Last edited 22/01/16 9:55 am

      No. We can't.


        I for one welcome our new Planet X overlords

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