Deakin Communicating Science 2016

EES 200/101

How are we going to find Planet 9?

Over the past 3 weeks I’ve been talking about planet 9, who discovered it (possibly) and the possible implications of Planet 9’s discovery, however wild they may be. But I haven’t put that much detail into what is being done to find it and what scientists believe it to be made of.

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Figure 1 Planet 9’s composition; available at

Let’s start with what planet 9 is made of. The above image shows what scientist believe Planet 9 to be composed of. Basically a mass of Ice and dense gases with a solid iron core. It’s the residual heat from the iron core that is what the Subaru telescope in Hawaii will be searching for.

Black body radiation is the light wavelengths that are emitted from everything with a temperature above 0oK… so everything.  And basically the hotter something is the more blackbody radiation it released and once it gets to a high enough temperature the light wavelengths actually become visible. Think, when steel gets red hot (not that Planet 9 is anywhere near that hot). Since the amount of light that is predicted to reach Planet 9 is so small infrared radiation is the only way to visibly identify the body.

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Figure 2 Planet 9’s estimated location; available at:

Now the Subaru will be looking for Planet 9 in the rather large area in the image shown above. It is rather large but based off the other orbits this is the most likely place for it to be located along its predicted orbital path.

There are two different groups attempting to find Planet 9 using Blackbody Radiation.
The first group, led by Nicholas B. Cowan, found that our current telescopes will be viable to find the planet as long as we point it in the right direction. And even if their estimates are off I we get lucky we are still likely to find Planet 9 as long as we point it in the right direction.

The second group, led by Siven Ginzburg, believe that due to Planet 9’s relatively dense atmosphere its temperature will still be around that of Uranus’ and Neptune’s. So the specific Temperature that Ginzburg’s group at the Hebrew University of Jerusalem is predicted to be between 28-53oK.

Once the Planet is isolated and the actual temperature is known scientists will be able to begin making assumptions about the compositions of the planets atmosphere.

Pretty cool huh?


Science alert/Brendan Cole. 2016. Physicists think they’ve finally figured out how to locate Planet Nine. [ONLINE] Available at: [Accessed 7 May 2016].Ginsburg, S, 2016.

Blackbody Radiation from Isolated Neptunes. The Astrophysical Journal Letters, [Online]. Volume 822/ number 1. Available at: [Accessed 7 May 2016].

Cowan, N.B, 2016. COSMOLOGISTS IN SEARCH OF PLANET NINE: THE CASE FOR CMB EXPERIMENTS. The Astrophysical Journal Letters, [Online]. Volume 822/ number 1, 1. Available at:


One comment on “How are we going to find Planet 9?

  1. cjhadley
    May 8, 2016

    I was watching youtube videos on the finding of planet X and found it very interesting, a lot of it was conspiracies and such but the history of it intrigued me. That it is said to be in such an orbit that it comes into view only every few thousand years. I’m pretty sure one video said they overestimated the mass of Neptune which is what caused the initial belief that there was a planet x but it was later proven this difference isnt that significant and there still could be a planet x


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This entry was posted on May 8, 2016 by in Uncategorized.

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