PLANET 9 Could there be more planets in our solar system?
Planet 9 is a hypothetical planet larger than Earth, far beyond Neptune's orbit, in the
darkest and farthest corners of the solar system, but could there be such a giant planet
in our solar system that we haven't yet discovered?
How could such a big planet hide from our most powerful telescopes?
Stay to find out!
"Introductory video"
The idea that there is a ninth planet in our solar system is nothing new; since 1906, the
astronomer Percival Lowell proposed the idea that beyond the orbits of Neptune, there was
a ninth planet that disturbed the orbits of the gas giants Uranus and Neptune, which he
called "Planet X."
Although for many astronomers the anomalies in the orbits of the outermost gas giant planets
of the solar system could be explained without the need to invent any ninth planet, other
astronomers supported the idea, since in the past it had been shown that the anomalies
of the Planet Uranus were due to an eighth planet not yet discovered, this Planet ended
up being Neptune.
Years later, in 1930, the astronomer Clyde William Tombaugh one of the adepts to the
idea of planet X and faithful follower of Percival Lowell, would manage to demonstrate
the existence of a ninth planet beyond the orbit of Neptune; this would be Pluto.
For 70 years, Pluto was named as the ninth Planet that had been so much sought, however
during all those years; Pluto was always a matter of debate by much of the international
astronomical community, who were not sure if classifying as "PLANET" a body as small
as Pluto was correct.
Astronomers expected the ninth Planet to be six times larger than Earth.
Still, Pluto was even smaller than the moon, plus other solar system bodies like Ceres
also had very similar characteristics to Pluto.
The solution reached by the International Astronomical Union (IAU) in 2006 was to reclassify
our definition of Planet so that from then on, a planet had to meet at least three requirements:
1.
Orbit around the sun.
2.
Have a mass of at least half the moon.
3.
Youner orbital dominance.
Orbital dominance is a process in which a massive body sweeps the entire area through
which it passes due to its gravitational pull force.
Over time, its orbit around the sun is free of asteroids or other small bodies.
Pluto did not meet this last requirement, so it was downgraded to "Dwarf Planet," a
new classification that includes other bodies very similar to Pluto, such as Ceres, Eris,
Makemake, and Haumea.
In addition, another new definition was added to classify bodies that were beyond the orbit
of Neptune but that do not meet the size to be considered planets; these would be the
Trans-Neptunian Objects (TON) that are bodies whose orbits extend beyond that of Neptune,
with Pluto being the first of these bodies.
In this way, Pluto falls within two classifications; on the one hand, it is a dwarf planet, but
it is also a trans-Neptunian body.
From here, things calmed down a bit regarding the classification of Pluto, and the search
for the ninth Planet began to take more and more strength.
KUIPER BELT Long before Pluto was downgraded to a dwarf
planet, astronomers already suspected that it was highly likely that a massive body existed
beyond Neptune's orbit, and the reason for this was due to Kuiper belt asteroids.
The Kuiper belt is an asteroid belt beyond Neptune's orbit, similar to the asteroid belt
between Mars and Jupiter.
This asteroid belt is characterized by being the most distant the sun and having objects
with eccentric orbits; that is, they get very close and far from the sun but never get more
relative to the orbit of Neptune.
In 2014 astronomers Chadwick A. Trujillo and Scott S. Sheppard found a new object very
similar to the trans-Neptunian object Sedna; this unique object was classified as 2012
VP 113 and shared many features with Sedna. (1)
According to Trujillo and Sheppard, both bodies have orbits within a region that would reach
from the Kuiper belt to the outermost area of our solar system, the supposed outer cloud
of Oort, which is about 10,000 AU away from the sun.
This means that both Sedna and 2012 VP 113 are not isolated bodies but make up a population
of relatively large bodies in the farthest areas of the solar system, in addition to
at least 12 Kuiper belt objects along with Sedna and 2012 VP 113 have orbital groupings
that do not seem to be the product of chance.
(2)
In other words, in the Kuiper belt, there are bodies slightly smaller than the moon
that cluster together for no apparent reason and seem to be influenced by another body
much more a massive group within those regions.
Other studies such as those of astrophysicist Cory Shankman of the University of British
Columbia have found a series of Trans-Neptunian Bodies (TON) with the help of the database
of the Minor Planet Center (MPC) in which there are small groups of TON with clustered
orbits that could be being influenced by the presence of a massive body that diverts them
from their orbits and groups them that way.
(4)
Astronomers Michael E. Brown and Konstantin Batygin of the California Institute of Technology
attempted to explain the behavior of all these trans-Neptunian bodies and objects within
the Kuiper belt using a computer simulation in which they placed bodies of different size
and density in the region near these bodies.
(3)
They determined that the only way to explain the orbital groupings of all these bodies
is to place a planet of 5 Earth masses within that region, that is, a planet much larger
than the Earth called "SUPER-EARTH," but smaller than Neptune, which may be causing the orbital
groupings.
Everything seems to point to the fact that there is indeed the ninth Planet far beyond
the orbit of Neptune; Brown and Batygin even propose that if it existed, this ninth Planet
would have an orbit around the sun of 7,400 years.
But... if this is the case and there is a planet five times larger than the Earth in
the farthest area of the solar system, how come we have not found something so big?
And a better question would be, can planets of that size exist?
SUPER-EARTHS AND MINI-NEPTUNES IN THE GALAXY Since the possibility that a super-Earth could
exist in the far reaches of the solar system was raised, the idea of planet 9 began to
gain more and more followers among the community of astronomers.
As we studied other solar systems, we realized that if we compare our solar system with others,
ours is particularly strange.
This is because, in our solar system, there are tiny rocky planets and giant gaseous planets
that have seemed normal to us for centuries.
Still, when we study other solar systems, we realize that this is strange since most
solar systems have super-Earths and mini-Neptunes.
Super-Earths are a type of rocky Planet with five times the mass of the Earth, and mini-Neptunes
are gaseous planets much more minor than Neptune with up to 10 times the mass of the Earth.
Those two types of planets would be like intermediate versions between the mini rocky and gas giants
that our solar system has and, in turn, are the most common in most solar systems that
we have discovered so far.
Still, we do not find either of those two types of planets in our solar system.
Could it be that, in reality, our solar system does have such a planet in the most remote
areas?
And if that is the case?
How come astronomers have overlooked such a vast body out there?
THE IMMENSITY OF THE SOLAR SYSTEM We haven't been able to locate such a large
body because the solar system is vast, and the farther away we observe, the darker it
is.
Remember that, unlike stars, planets can not emit their brightness; because of this, the
only way to see them is thanks to the fact that the sun illuminates the planets, and
the reflection of that brightness is what allows us to see them.
Because of this, the farther away the planets are from the sun, they will be much darker
since they receive less solar radiation, and therefore, they are much colder.
That is to say that as we look for objects more and more distant, things get complicated;
another factor to consider is how astronomers study the sky.
Finding a planet is not as easy as it seems; However, the planets closer to the Earth can
even be seen without telescopes; the farthest, although more bigs, are also challenging to
see and even more so for astronomers who did not know where to look for them.
Contrary to what is thought, when astronomers look for planets, they do not look for that
body that looks different from other stars; on the contrary, they have to check each of
the stars in the sky and see which of them behaves differently from the others.
In a telescope, a faraway planet looks ideally like a star; the only difference between the
two is that when observed for a long time, the planets move concerning the background
of stars behind them, while the stars remain motionless in place.
If Planet nine exists, the only way to detect it will be to observe the sky for extended
periods and check which stars move.
In the US, there is a project called Zwicky Transient Facility (ZTF), which is an astronomical
study of the wide-field sky that uses a new camera connected to the Samuel Oschin telescope
at the Palomar Observatory in California; this project has found to date of its operation
more than 13 million objects of period long iodine orbiting the sun in the farthest regions
of the solar system.
(5)
Imagine that, 13 million, finding Planet nine among all these bodies is like looking for
a needle in an ocean full of more needle; it's an immeasurable figure.
Fortunately, we don't have to check them all as there are methods to rule out many of them.
Unlike the stars, the planets are in a specific region of the sky; this region is what we
call "Ecliptic" is the area of the solar system where planets usually orbit around the sun,
and it is scarce that a planet or any other or object such as asteroids or comets are
too far from that area.
Discarding all objects outside that region of the ecliptic, we have less than half.
In addition, we can also discard those that are smaller and focus only on those that could
meet the requirement of a planet five times more massive than the Earth.
But even making all these adjustments and discarding all these bodies, we are still
left with a relatively significant figure of at least 100,000 objects that could be
The Planet 9, that without the guarantee that any of those 100,000 is the Planet we are
looking for.
As you can see, finding a planet in the farthest areas of the solar system is a titanic task,
although there is a possibility that Planet nine has already been found, and we have not
yet realized it.
WE MAY HAVE ALREADY FOUND IT, AND WE DON'T KNOW
In 1781 the astronomer William Herschel discovered the planet Uranus thanks to the observations
he made with his telescope.
Still, he declared that it was not a planet but rather a comet.
Like any astronomer and scientist skeptical in his discoveries, Herschel did not want
to claim that his discovery was a planet without first having the opinions of other experts.
Thus, two years later, the most eminent astronomers in Europe corroborated Herschell's observations
concluding that the new object was a Planet.
Later with mathematical calculations derived from the orbit of Uranus, astronomer Urbain
Le Verrier managed to determine with great precision the position of the planet Neptune
in 1846.
And thanks to the most recent research, we realized that all these planets had already
been recorded by the population for a long time before.
In 1690 the astronomer John Flamsteed observed the planet Uranus at least six times and classified
it as 34 Tauri, that is to say, as one more star in the sky, he died without realizing
he had discovered Uranus almost 100 years beforeWilliamHerschell.
Also, in 1612 astronomer Galileo Galilei managed to observe Neptune repeatedly while observing
the planet Jupiter.
Still, just as Flamsteed described it as a star and not a planet, Galileo discovered
Neptune almost 200 years before Leverrier.
Even more recently, astronomer Brown, who discovered the dwarf Planet Eris at the Palomar
Observatory in 2005, found that the first image of this body was on a photographic plate
made by the same telescope in 1955, more than 50 years ago!
That is why many astronomers think that we may even have images of Planet nine made by
one of the modern telescopes, but we have not yet realized that it is there, it hides
in plain sight, and very soon, we will discover it.