One of the more interesting prospects in space related news today is the growing possibility
of a ninth planet existing in the outer solar system.
Unlike much of what I cover on this channel, the existence of another large planet in our
solar system is not really in unlikely territory anymore, but rather mounting evidence makes
it now seem very possible.
And while we have not located it or observed it, it seems like we're seeing the effects
of its gravity in a very specific and telltale way in the outer solar system.
The inner solar system is a relatively ordered and quiet place as far as gravity goes.
This was not always so, but has settled down to be this way over time.
In contrast, the outer solar system is still somewhat of a mess.
There's an abundance of material out there that is constantly affecting other material
gravitationally and that results in some very odd, highly elliptical orbits.
That interaction is why comets enter the inner solar system periodically.
But there are also irregularities in the orbits of the larger objects in the outer solar system,
particularly the minor planets known as trans-Neptunian objects.
One of the more famous of these, Sedna, is in a mystifying eccentric orbit that isn't
easily explained.
Other objects such as the more recently found minor planet 2012 VP 113 share certain characteristics
with Sedna's orbit and seem to indicate that something large has perturbed them into those
orbits, and this is best explained through the presence of a large planet that's close
enough to the Kuiper belt to affect objects within it gravitationally, but far enough
from the inner solar to not affect the inner planets.
The evidence continues to mount as discovery of more objects with orbits consistent with
Planet 9's existence have been found.
If another 2 or 3 further ones are found, then Planet 9 statistically moves to solid
ground with a high probability of being out there.
If another 10 to 20 objects are found, then their orbits will allow us to pin down Planet
9's position.
But it's also possible that it might be spotted earlier, at any time really.
By looking at the orbits of the trans-Neptunian objects and keeping in mind factors such as
the inner solar system's absence of effect, scientists have determined that if the ninth
planet does exist a good guess would probably be that its about two to four times the size
of Earth and might be an ice giant similar to Neptune or Uranus.
But there are many factors that affect that, so it's possible for it to be larger or smaller
than that too.
It's even been suggested that it may be the primordial core of a giant planet that was
ejected from the inner solar system during the solar system's nebular epoch.
In fact, a five giant planet variation of the Nice model of the solar system's evolution
predicts the existence just such a planet, though it's not clear if planet nine could
fit the bill.
It's also possible that the planet formed in the outer solar system, however, due to
the fact that Planet Nine would need to have a highly elliptical orbit to explain the interactions
with the minor planets, an alternative origin for this hypothetical world is also possible.
It has been suggested that Planet 9, should it exist, might have been captured from another
star early in the sun's history when it was part of a cluster of stars that it formed
with or even captured it as a rogue planet that was wandering the interstellar medium.
While an origin within our Solar System seems more likely, it's certainly an interesting
thought that a planet not native to our star system may lurk at its edges.
Now you might be asking if such a thing will be classed as a planet at all, given the demotion
of poor Pluto years back.
The answer is most likely yes, it would be large enough to meet the criteria required
for a planet.
Even at it's smallest possible size, it's still at least borderline.
It's also likely that if discovered it would receive the name of a Greek or Roman deity
to remain in line with the naming scheme of the rest of the solar system.
And that brings us to another peculiarity I have been wondering about, so a little speculation
is in order.
In 1984, several independent scientists suggested that a second star might orbit the sun as
a binary system.
This theoretical star, named Nemesis, would be a small red or brown dwarf and would be
so dim and distant that it would only be visible in a telescope.
No such thing was ever found, and it should have been if it existed given the multiple
studies and space telescopes of the intervening years.
So the Nemesis theory seems to be dead now, but it raises an interesting point.
The presence of the Nemesis star was originally theorized in order to explain an apparent
pattern of regularity in mass extinctions on earth, the idea being that something periodically
was disturbing the Oort cloud and sending deadly comets our way.
That pattern, which comes out to about once every 27 million years, was strengthened by
research done in 2010 suggesting that it may not just be chance and the pattern really
is there.
If true, and this is pure speculation, it might turn out that Planet Nine is responsible
for some of the mass extinctions of life on earth.
On the other hand, it's orbital period, which is thought to be between 10,000 and 20,000
years, probably makes that unlikely.
But we won't know for sure until we know more.
So there you have it, Planet Nine is moving into probable territory.
Check back to this channel as I will be releasing updates on developments regarding this possible
planet as new information comes to light.
Thanks for listening.
I am futurist and science fiction author John Michael Godier currently celebrating one thousand
subscribers to the channel and I just want to thank all of you, I appreciate your support.
It's been rewarding and fun to make these videos so expect many more and be sure to
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for in-depth regular explorations into the interesting, weird and unknown aspects of
this amazing universe in which we live.