Current science says that there are only eight planets in the solar system,
a handful of dwarf planets, and countless asteroids. Over the last few centuries,
our understanding of the cosmos has grown so much that we now know a lot about how the planets work,
what they’re made of, and whether they might be a future home for humanity. But could there still be
much more to learn about our own star system? This is Unveiled, and today we’re answering
the extraordinary question: can the James Webb Space Telescope finally find Planet 9?
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There are at least two theories about an additional, ninth planet roaming the
solar system somewhere at the edge of the sun’s heliosphere. The first, “Planet 9”,
is proposed by scientists to explain certain eccentricities and abnormalities in the orbits
of the outer planets and the many trans-Neptunian objects. The second, “Planet X” or “Nibiru”, is a
conspiracy theory that says this ninth planet is going to crash into Earth and destroy us. Various
dates have been given for this cataclysm, but not only have none come to fruition,
we also have no evidence that a large planet is hurtling toward us in the first place.
Today, we’re focussing not on Nibiru, but on Planet 9. Planet 9 is decidedly NOT a conspiracy
theory, and is an idea that many astronomers are interested in researching as one potential
explanation for various strange orbits in our particular corner of space. Planet 9 (rather than
Nibiru) also poses no danger of ever crashing into us here on Earth. If Planet 9 does exist, it’s
likely existed for as long as the entire rest of the solar system and the other planets have – for
more than 4.5 billion years. It hasn’t threatened us yet, so it’s unlikely to do so in future.
But that doesn’t mean it’s not deeply interesting, or that our quickly developing tools for
scientific research couldn’t one day find it. On Christmas Day, 2021, NASA finally launched
its expensive and much-delayed space telescope, the James Webb. It’s the most powerful space
telescope we’ve ever built, and is NASA’s new flagship, replacing the Hubble Space Telescope.
Hubble is still operational, and still capable of conducting plenty of research on its own,
but we now have Webb to study objects and areas of space in far greater detail than ever before. Both
telescopes, though, have the benefit of seeing in infrared. This means that they’re designed
to capture light from the infrared end of the electromagnetic spectrum… and to translate that
light into images. Without that process, infrared light is invisible to the human eye because it’s
beyond the visible light spectrum. But plenty of objects in outer space emit infrared rays…
including cooler objects, like red and brown dwarfs, cosmic dust, and even some planets.
Closer to home, we can use infrared to study objects we already know about but in new ways;
such as in 2022, when Webb produced some stunning, infrared images of Jupiter, showing the planet’s
polar auroras. The thinking is, then, that if it can capture Jupiter in never-before-seen detail,
then it could also be the best tool to definitively prove the existence of Planet 9.
But just what sort of evidence already exists to support the ninth planet theory? In 1930, Clyde
Tombaugh discovered Pluto, thought for decades to be this mysterious, ninth planet. It was thought
that Pluto could explain apparent perturbations in the orbits of Neptune and Uranus. It was later
established, however, that these perturbations didn’t actually exist and were simply a result
of erroneous calculations… and also that Pluto was much too small to have caused them even if
they were correct. Pluto was eventually downgraded to a dwarf planet, although it now has the honor
of being the first-ever trans-Neptunian object discovered. We now know that beyond Neptune,
there are countless more objects like this of various sizes, making up the Kuiper Belt and,
more distantly, the Oort Cloud. For today’s astronomers, however, it’s these objects in the
Kuiper Belt, with their warped and erratic orbital patterns, that are so intriguing.
A dwarf planet like Eris, which actually has more mass than Pluto, is one of them. It takes 559
years to orbit the sun and its orbit is extremely elliptical, as if it’s being pulled further from
the sun by some other, gravitationally powerful object in the distant realms of our solar system –
Planet 9, perhaps. There’s also the dwarf planet Sedna, so far away it can take as long as five
days for light to reach it from the sun. Sedna takes over 11,400 years to complete one orbit.
And again, its orbit is extremely elliptical, as if it’s being pulled away in one direction.
Sedna’s orbit ranges from 76 Astronomical Units from the Sun (meaning 76 times the distance
from Earth to the Sun) to a whopping 937! So, it’s theorized that there’s something out
there causing these objects to have such unusual orbits, and that Planet 9 could be that thing. To
accomplish this, it’s been calculated that Planet 9 would need to be between 5 and 10
times more massive than Earth is. This is still relatively small, considering that Jupiter is more
than 300 times more massive than Earth. This means that Planet 9 - if it is there - would
be a super-Earth. And super-Earths, despite seeming strange to us here in the solar system,
are actually extremely common elsewhere. It wouldn’t be weird at all for our solar
system to have a super-Earth, then. However, its projected size and distance would make it very
difficult for us to find. It would be smaller than all of the ice and gas giants that we know about,
perhaps half as massive as Neptune, making it far from easy to just discover.
We also have to examine the entire night sky in a wide circle to try to find it wherever it may
be in its orbit. And it’s worth remembering that while the likes of Jupiter are visible
with the naked eye, both Uranus and Neptune are not. They’re too far away… but Planet 9 would
be further still. It’s why we know far less than you might think about the outer solar
system… so much so that the discovery of an additional planet lurking hidden
there has already happened in history, with the cases of the ice giants - Uranus and Neptune.
But if Planet 9 DOES exist, and the James Webb Space Telescope does find it,
how will this affect us on Earth? It would be a landmark moment in science if our cutting-edge
technology were able to find a planet so far away, proving without a doubt that astronomy is worth
every penny spent on it. If it’s an ice giant like Neptune and Uranus it’ll be interesting to study,
and there’s the potential that it could have moons, lots of them,
as all the gas giants we know of have plenty of their own. But could it also be a rocky world?
Regardless, and unfortunately, its extreme distance from the sun means that it would be
so cold it may as well not be orbiting a star at all, rendering it almost completely uninhabitable.
Neptune’s rocky moon Triton has surface temperatures of around -390 degrees Fahrenheit,
making it nearly as cold as outer space itself, and pushing it pretty near absolute
zero. Tidal warming inside a celestial body can generate heat, but likely not
to the level that such a planet or any of its moons could be warm enough to live on. Still,
we have built structures that can withstand the cold of outer space, so we COULD feasibly build
something on Planet 9 or a rocky moon of it - if we were to work out how to get there. While
it’s extremely far away, such an outpost would be useful both from a scientific point of view,
and from an interstellar perspective. In a far off time, Planet 9 could be a final rest-stop
for future humans on their way beyond the solar system. It would also be an interesting base
from which to study the enigmatic Kuiper Belt in full, and even the Oort Cloud.
There are still, though, other explanations for what could be affecting the orbits of Eris, Sedna,
and others. It’s a little more accepted that the perturbations and discrepancies this far out could
all be due to the collective gravity of the many Trans-Neptunian Objects, asteroids, and comets,
rather than one single entity. Since previous infrared studies have so far been unable to
find Planet 9, and other studies have directly disputed its existence, the collective gravity
explanation is perhaps currently more viable. But, then again, no single mission has ever
had the potential to rewrite the story quite like the James Webb Space Telescope does.
If Planet 9 really is out there, then this is a machine that’s more than capable of finding it,
and perhaps someday soon. And that’s why Webb COULD find Planet 9.
What do you think? Is there anything we missed? Let us know in the comments, check out these other
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