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Malecki 1
CHAPTER 1
INTRODUCTION
1.1 Jovian Planetary System
Some of the most prolific and profound objects in our solar system are the Jovian gas
giants. These massive swirling bodies of gas and ice have been the fascination of the ancient star
gazers to today’s well renowned astronomers and astrophysicists. Our own solar system is
comprised of four of its own gas giants: Neptune, Uranus, Saturn and Jupiter.
In our solar system these four Jovian planets all lie on the outer edges of the solar system
past the asteroid belt with the closest, Jupiter, lying 5.2 astronomical units (4.836 x 108 miles)
and the furthest, Neptune lying 30.1 astronomical units (2.7993 x 109 miles) away. The
characteristics making these planets so different from the other four terrestrial planets are two
basic facts:
1.) Immense size difference.
2.) Gas composition with liquid inner layer.
When studied these differences become extremely clear with hundreds of earth-sized
planets being able to fit into their Jovian counterparts. Part of the reason for this is the material
they are made out of. Typical terrestrial planets have thin crusts of a silicate mineral
composition with very dense metallic cores mostly composed of iron, nickel and several other
heavy metals. Some may wonder why the gas giants are all on the outer reaches of the solar
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system and all the terrestrial bodies are inward closer to the Sun. Astronomers have developed a
widely accepted theory accurately telling why this is.
In the early solar system, “Gravity from our young star pulled in much of the free-
floating gas… while the solar wind of particles streaming from the Sun also swept the gas
outward” (Sparrow 52). When the Sun was younger, it produced much more heat and energy as
it developed. It created massive solar winds that pushed the lighter elements like hydrogen and
helium, the main components of the gas giants Jupiter and Saturn, back to the further reaches of
the solar system. As a result of this the heavier particles of rock and metal were left and
influenced by the Sun’s gravitational force and began to grow larger and accumulated more
particles and mass to create the rocky and dense planetesimals that would be the base for the
terrestrial inner planets. Figure 1.1
However, the lighter elements were
pushed back by these solar winds and were
joined together rather quickly due to
gravitational forces.
There are two debated models upon
which astronomers and astrophysicists
believe the Jovian planets formed, the core
accretion model or the gravitational
instability model (Metchev). The first and
more widely accepted model, the core accretion
model, shown in Figure 1.1, states once a
planetesimal has formed, it would then have
As the planetesimal forms, it gathers mass at an exponential rate once it reaches its runaway point.
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sufficient gravitational influence on the surrounding gas to begin rapidly gaining mass due to the
accretion of gas molecules blown away from a star’s initial releases of solar winds. This process
continues in the gas-rich outer edges of a solar system until there is no longer any more gas to
pull in, resulting in the final planet.
The second model for the creation of gas giants is the gravitational instability model.
This model states huge clouds of gasses detached from the initial star forming nebula, began to
rapidly spin under their own angular velocity and eventually begin falling in on themselves
creating the planet (Sparrow 52). These two theories are at odds as the core accretion model
only explains how planets of this nature form within the confines of a 30 AU orbital radius form
its parent star and gravitational instability is only effective at explaining planets around
extremely massive parent stars, nothing comparable to a star like GJ 504 or our Sun.
Nonetheless, when they came together, the Jovian gas giants were formed with masses of
Uranus’s 8.86 x 1025 kilograms to Jupiter’s 1.90 x 1027 kilograms although giant gas planets as a
whole are not limited to these parameters and can exceed or deceed them. Due to the great mass
of the accumulated gas clouds that surround the rocky inner cores, the pressures and
temperatures greatly increase as you travel further into the atmosphere. Chris Impey states,
“Data shows (of Voyager and Galileo probes), the upper atmospheres are cold, but below the
cloud layers, their lower atmospheres are hot and have high air pressure.”
1.2 GJ 504 b and Its Parent Star
In the constellation Virgo lies a star named GJ 504. GJ 504 is G0 type main-sequence
star that lies approximately 57 light years away and is believed to be around 160 million years
old (Reddy). It has a mass of about 1.2 solar masses and has a rotational period of about 3.33
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days (Kuzuhara). This star is not really out of the ordinary and actually often compared to the
Sun, resembling size and temperature. It is a fairly common star with no notable anomalies
about it. In Table 1.1 is a fact table of GJ 504.
Table 1.1
The strange thing about this star is its one identified planet, GJ 504 b. This star gets its
name from its parent star GJ 504 where “b” stands for the planet’s position as the second object
in the system while GJ 504 would be considered first. The planet was discovered in 2013 by the
Strategic Exploration of Exoplanets and Disks with Subaru or SEEDS (Kuzuhara). “GJ 504 b is
about four times as massive as Jupiter and is about 460 degrees Fahrenheit (511 K)”
(Westerholm). A planet four times the mass of Jupiter would equate to 7.6 x 1027 kilograms or
approximately 1,300 times the mass of the Earth. This planet is quite peculiar and according to
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accepted scientific models of how gas giants form, shouldn’t exist based on its mass and distance
from GJ 504.
Like Jupiter, GJ 504 b is also a gas giant. This planet, unlike Jupiter’s rusted red color, is
a very deep swirling purple or magenta color. However, this isn’t a typical gas giant planet.
There are certain aspects of this planet that have astrophysicists perplexed. These aspects will be
viewed in greater depth in the next section.
1.3 Discovery of GJ 504 b and Its Significance
Like previously stated, GJ 504 b was discovered in 2013 by the Strategic Exploration of
Exoplanets and Disks with Subaru (SEEDS) program. The SEEDS team comprised of 120
members, led by Motohide Tamura of the University of Japan, has been utilizing the Subaru
Telescope since 2009 to view approximately 500 stars in an effort to find new exoplanets
(Subaru). GJ 504 b is a product of this ongoing search. The team took a direct-imaging
approach in order to photograph this planet by fixing the Subaru Telescope on GJ 504 in order to
see what it could find. Below is the first direct-imaging result the SEEDS team took:
Figure 1.2
This was the one of the first published photos produced by the SEEDS team and the Subaru Telescope. Directly centered is the parent star GJ 504 with GJ 504 b to the top right. An outline of Neptune’s orbit is given for scale.
Photo Credit: Sci.News.com and Subaru Telescope
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The photo in Figure 1.3 is what perplexed the SEEDS team. Upon comparing the orbit of GJ
504 b to that of Neptune’s they realized the problems the planet itself was posing. According to
current accepted models, mainly the core accretion model, this planet should not have been able
to form.
The core accretion model only complies with planets within 30 AUs of their planet star.
GJ 504 b lies about 50 AUs away. GJ 504 b far exceeds that boundary as the model states there
would not have been a sufficient amount of material for a planet of that size and mass to form.
At this point some astronomers and astrophysicists would argue the gravitational instability
model could easily be applied. However, GJ 504 is a medium sized main-sequence star born out
of a smaller nebula, a situation that would have nowhere near enough mass to allow the
collapsing in of the gas molecules from the clouds angular velocity alone.
This predicament is what is making GJ 504 b such a special case. As of now, science has
no sound way of explaining why and how this planet was able to form. It completely contradicts
everything astronomers know about how Jovian gas giants form. Because of this, there is no
doubt this planet will continue to be scrutinized and studied to see what researchers can further
unlock about this planet and what exactly caused it to form in such different circumstances.
Directly comparing GJ 504 b to a standard cookie cutter gas giant like Jupiter will hopefully
bring about new thoughts onto why this planet is so different.
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CHAPTER 2
PHYISCAL CHARACTERISTICS
2.1 Appearance
When it comes to appearances, Jupiter could be considered one of the most dazzling to
look at, and for good reason. Its deep rusted red and blaze orange atmosphere dance in stratified
lines across the planet’s atmosphere. These lines and colors are not just by coincidence though.
There is a major connection of atmospheric pressures, chemical presence, and movement
resulting in the outer appearance of Jupiter. Likewise, GJ 504 b is also believed to have
stratified layers of alternating colored lines but in deep purples and bright fuchsias. GJ 504 b’s
color is direct result of the mass amounts of methane that comprise a large majority of its
atmosphere (Kuzuhara). Jupiter’s orange and reddish colors are a result of the chemical
reactions taken place in its atmosphere. However, more of what gives each planet their colors
will be looked at in greater depth in Chapter 3.1.
Gas giants like Jupiter and GJ 504 b tend to have much larger sizes compared to their
terrestrial counterparts. Part of the reason for this is their very low densities. Gas giants usually
possess a much greater amount of mass, but spread out over a much greater sphere. Rocky
terrestrial planets like Earth have much less matter comprising their makeup but it is crammed
into much smaller sphere resulting a significantly higher density, as seen below:
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Volume= 4/3πr3
Earth Jupiter
V=4/3π(6,378 km.3) V=4/3π(71,492km.3)
V=1.087 x 1012 km.3 or 1.087 x 1027 cm.3 V=1.531 x 1015 km.3 or 1.531 x 1030 cm.3
Density=Mass/Volume
Earth Jupiter
D=5.98 x 1024 kg. / 1.087 x 1027 cm.3 D= 1.90 x 1030 g. / 1.531 x 1030 cm.3
Density = 5.5 g /cm.3 Density = 1.2 g./cm.3
As you can see from the calculations above, terrestrial planets, like Earth, are
substantially denser than their Jovian counterparts. While there will obviously be variations in
the densities of all planets, it can be concluded terrestrials have a much higher density. The
densities among gas giants also vary greatly. However, since GJ 504 b is roughly four times the
mass of Jupiter (7.6 x 1027 kilograms), its true density is open to interpretation and further study
as there have been no conclusive tests that would have led to figuring out the exact radius of GJ
504 b; a variable needed to find its volume and consequently its density. The average density of
our solar system’s Jovian planets is 1.232 g./cm.3, an average which Jupiter lies extremely close
to. Based on these observations, it would not be crazy to speculate GJ 504 b’s average density
lies near our solar system’s Jovians’ average density. Unfortunately, the actual number will not
be able to come to fruition until more research is done by the SEEDS team. Simply finding the
planet’s linear diameter would give us the ability to calculate GJ 504 b’s actual density.
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2.2 Moons
Comparison of Jupiter’s Galilean Moo
Moon Radius Mass (kg.) Distance from Jupiter
Io 1821.6 km. 8.932 x 1022 kg. 4.216 x 105 km.
Europa 1560.8 km. 4.800 x 1022 kg. 6.709 x 105 km.
Ganymede 2631.2 km. 1.482 x 1022 kg. 1.070 x 106 km.
Callisto 2410.3 km. 1.076 x 1023 kg. 1.883 x 106 km.
One of Jupiter’s most notable characteristics is its moons. Jupiter’s immense mass acts like a
gravitational magnet for all sorts of space debris and rock. Although the number frequently
changes, at the time of the publication of this paper, Jupiter is believed to have 67 recognized
moons. These moons vary greatly in size and shape. Some are so large that they are spherical
due to their own gravity and others that are just smaller asteroid shaped objects of rock, ice, and
metal. The four largest moons, referred to as Galilean moons, after their discoverer Galileo
Galilei, are Io, Europa, Ganymede, and Callisto. These four moons have been a great wonder to
astronomers ever since Galileo first discovered them with his homemade telescope in the 1600s.
Residing in orbital distances (closest to further away from Jupiter) in the same order as listed
above, they can be seen with only a moderately powered telescope, a testament to the size of the
moons. As you can see in Table 2.1, the moons are fairly substantial in size and
Mercury 2240 km. 3.30 x 1023 kg.
mass, even rivaling the planet Mercury in certain dimensions such Ganymede having a greater
diameter and Callisto only being slightly less massive than Mercury.
Table 2.1*
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Scientists have been studying these moons for good reason. An ocean of liquid water is
believed to exist under the outer ice layer surrounding the moon Europa. Astronomers and
astrobiologists have good reason to believe that this life giving water could be a great contender
for containing extraterrestrial life. However, further tests and perhaps probing missions will
have to be done in order to conclude whether life not only lives there, but has the potential to live
there.
In regards to the moons of GJ 504 b, there has not been enough research on the planet to
produce a definitive answer as to whether or not the gas giant possesses any. Based on the
immense mass of the planet however, roughly 7.6 x 1027 kilograms, it is pretty clear that there
should be some moons gravitationally attracted to it. It would make sense and be logical to think
though that due to the planet’s mass, it would easily surpass the amount of moons Jupiter has.
Four times the mass could roughly equal four times the gravitational influence on the space
around it.
The presence of at least one moon is extremely plausible and more than likely the case.
However, being able to find these exoplanets like GJ 504 b is hard enough. Therefore, the idea
of imaging a moon of some sort is almost inconceivable based on their predicted size and the fact
that they would not give off any form of radiation of their own.
Mass is not the only factor when speaking of moons. One huge variable surrounding the
formation and acquisition of moons is the amount of debris that was present around the planet
when it formed. It is believed that through an idea called the Giant Impact Theory, our own
moon was a left over remnant of an asteroid impact in Earth’s early stages of life. This asteroid
became gravitationally locked and continued to form and accrete more and more space debris
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floating around the Earth, rounding out as a result of its own gravity pulling inward, and
eventually forming the moon we have today.
2.2 Other Satellite Systems
A satellite like system GJ 504 b could very well possess is a ring system. Saturn and
Uranus are known for their rins systems that are as beautiful as they are intricate. However,
these are not the only ones as all Jovian planets have rings, as seen in Figure 2.1. Jupiter also has
a small series of rings only 30 km. thick; merely a plane of dust particles orbing its equator
(Sparrow 55). Rings systems actually tend to be a fairly common occurrence amongst high mass
planets, typically gas giants.
This leads no reason to believe that GJ 504 b, a planet roughly four times the mass of
Jupiter, wouldn’t be a suitable contender for a ring system. This could especially be the case if
the GJ 504 system possesses a Kuiper belt-like structure. This could have the potential to be a
Figure 2.1*
*Figure provided by University of Oregon Astronomy Department
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prime location for picking up pieces and fragments or rocks and icy bodies capable of venturing
too close the gravitational pull of GJ 504 b.
As I stated in Chapter I, gas giants form so far out because only the lighter gas molecules
could be pushed by the sun’s radiation, approximately five AU’s out. These are the molecules
having formed together in order to create these types of planets. GJ 504 b sits 50 AU’s away
from GJ 504 b, 20 more than Neptune does from our own sun. At these distances, rocky and icy
bodies may become less and less easier to come by.
There is a high possibility that the GJ 504 system contains an asteroid belt-like
component, or perhaps a Kuiper belt component. Within our own solar system, the Kuiper Belt
spans from the edge of Neptune’s orbit all the way out to about 80 AUs from the sun, or 1.2 x
1010 kilometers. This span of roughly 50 AUs is an immense debris rich field. Remembering GJ
504 is similar to our sun in mass, the presence of a Kuiper belt-like feature could be
hypothesized to be at a similar distance. If so, GJ 504 b would be placed very closely, if not
directly in GJ 504’s debris field. These could very well aid to a possible “trapping” of any debris
or body of rock would happen to float too closely into GJ 504 b’s field of gravitational influence.
One could calculate a rough estimate of what GJ 504 b’s surface gravity is, reflecting the
pull it would extend to a passing object or moon. Based on two rough estimates, the mass of GJ
504 b and its density, an idea of its gravity can be calculated.
Using an average of the densities of all of our solar system’s Jovian planets and GJ 504
b’s estimated mass, we can come to a final number. Remembering that volume is equal to 4/3π
times the radius of the object cubed, we can rearrange the equation basing our volume off of our
Jovian planet’s average density (1.233 g./cm3) to find a rough estimation of GJ 504 b’s radius.
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Then using the formula for calculating the acceleration due to gravity, we can come up with a
very rough number to put on GJ 504 b’s gravitational influence, and then compare it to Jupiter.
Volume
V = mD
V = 7.6 x 1030 g .
1.233 g .cm .3
V = 6.164 x 1030 cm.3
After I found the volume by simply dividing the estimated mass of GJ 504 b by the
average density of our solar system’s Jovian planets to get a volume of 6.164 x 1030 cm.3. I can
then plug it into my new and rearranged formula for the volume of a sphere in order to find an
estimated radius of GJ 504 b.
Volume of a Sphere
V = 43 πr3
r= 3√ V43
π
r = 3√ 6.164 x 1030 cm .3
43
π
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r = 1.13 x 1010 cm. or 1.13 x 108 m. or 1.13 x 105 km.
As you can see, based upon my calculations and using an estimated average density of
1.233 g. /cm.3, I was able to hypothesize a potential radius for GJ 504 b. However, the margin
for error is great as the number used for density is only an average and not a legitimate
calculation of its density. Next, I calculated GJ 504 b’s surface gravity by using the value for
radius above.
Acceleration due to Gravity
g =Gmr2
g = (6.67 x 10−11 m3
kg . s .2 )(7.6 x 1027 kg .)
(1.13 x108 m. )2
g = 39.699 m/s2
According to my a calculations, the surface acceleration due to gravity can be concluded,
based on rough averages, to be 39.699 meters per second per second. This is an extremely
substantial gravitational influence.
In order to gauge the strength of this gravitational acceleration, take our Earth’s surface
acceleration due to gravity: 9.81 meters per second per second. GJ 504 b’s acceleration to due to
gravity is just barely over four times stronger. Earth has the greatest acceleration due to gravity
of all the terrestrial planets. When compared, GJ 504 b’s gravity dwarfs Jupiter’s 24.8 meters per
second per second (based upon my values and calculations). GJ 504 b’s surface gravity is almost
1.6 times stronger that Jupiter’s.
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With these values, and again the values for radius and mass in my calculations were
averages and estimations, respectively, it is clear to see that GJ 504 b is not lacking in the
gravitational influence department. A force like this would easily accommodate a multitude of
moons, natural satellites, and perhaps even a rings system. Based on my calculations, GJ 504 b
has significantly more gravitational pull, and has presented no reason to believe it would not
have a similar moon system.
Chapter III
Atmospheric Characteristics
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3.1 Chemical Makeup
In order to fully grasp just what a planet is made of, the planet’s chemical composition is
extremely important to examine. The planet’s chemical makeup leads to a lot factors. A planet’s
density, mass, coloration, and atmosphere can all be related to just what is making the planet tick
and what makes the planet unique. They are massive bodies of large amounts of gas that swirl
and react together to work in unison to create a final planet. In order to perform a proper
analysis of two massive gas giant planets, the examination of their atmospheric characteristics
need to be looked at.
First we will look at the chemical characteristics of the atmosphere of Jupiter. “Jupiter
boasts an enormous supply of hydrogen and helium that make it the most massive planet in the
solar system” (Redd). Close to 90% of Jupiter’s atmosphere is comprised of hydrogen, about
10% of the atmosphere is hydrogen, and there are small trace amounts of other gasses commonly
found in gas giants like compounds such as ammonia, sulfur, methane, and water vapor (Redd).
The majority of this hydrogen is all hydrogen leftover from the creation of the sun. When the
sun formed the massive accretion disk, it began to fall in on itself over time eventually becoming
massive and hot enough to ignite thermonuclear fusion in the sun’s core, beginning its energy
producing life.
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However, not all the hydrogen was able to fall in. Here is again where the two disputing
theories mentioned in Chapter I come into play, the core accretion model and the gravitational
instability model. To recap, the core accretion model, postulates that a small rocky and/or icy
body was able to form a planetesimal. This planetesimal then had a sufficient amount of
gravitational influence to begin collecting and pulling in the left over hydrogen, helium, and
other gas molecules. These molecular clouds left over eventually swarmed the planetesimal
forming the gas giant, as seen in Figure 3.1. This is the model that is more widely accepted by
scientists in the field of astronomy and more frequently referred to when speaking of Jovian
planetary formation.
The second model is the gravitational
instability model which states that gas
giants are created from a cloud of gas
detached from the initial formation of
the planet’s parent star. A molecular
cloud would have to detach itself from
the main protostar, obtain a sufficient
angular velocity, collapse in on itself,
and stabilize into the final planet.
These two debated models put
forth depend on different factors in
*Figure 3.1 courtesy of John Schombert, University of Oregon
Figure 3.1*
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order to operate efficiently, however there is a main similarity. Both the core accretion model
and gravitational instability disk model depend on an inner core for which the immense
atmosphere can gravitationally link on to. Unfortunately scientists have yet to provide proof of
an “Earth sized” rock, metallic, or icy core in the center of the planet. The atmospheres of gas
giants obviously vary in size and mass depending on the planet.
When studying the outer layer of Jupiter, the most prominent feature of the atmosphere
are the alternating layers of orange and white layers running parallel to the equator. What causes
Figure 3.2
The figure adjacent represents the chemicals that comprise the outer surface layer of Jupiter’s atmosphere. The outer clouds are comprised of NH3, or ammonia, that give way to ammonium hydrosulfide, then to basic water vapor clouds, before taking on a more crystallic nature of those chemicals.
Credit to John Schombert, University of Oregon
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these bands to show are alternating areas of high and low pressures that dance across the
atmosphere. The whiter and lighter bands are called zones. “The lighter clouds found in the
zones are dominated by ammonia crystals, which condense at lower temperatures than the
ammonium hydrosulphide…” (Sparrow 55). Similar to Earth, the further out you travel out of
Jupiter’s atmosphere the colder the temperature gets. The outer colder layer is where the lighter
zones reside.
The orange and brown darker bands are referred to as belts. These are the lower lying
bands that are results from higher pressure systems. Like previously stated, 90% of Jupiter is
comprised of hydrogen, about 9% helium, and the rest are a mixture of more complex ammonias
and similar chemicals. This 1% of other chemicals is what comprises a majority of the outer
layers as seen in Figure 3.2. These are all contained in the part of Jupiter’s atmosphere known as
the troposphere which is about 50 km. thick.
Scientists have a fairly good idea of what the chemical makeup of GJ 504 b is. Based on
direct imaging testing of GJ 504 b, Markus Jason concluded that the gas giant’s atmosphere
contains mass amounts of CH4S, a methane based organic compound called methanethiol. The
methane absorption test conducted by Jason confirmed the belief that CH4S was the dominant
methane based compound in the planet’s atmosphere, along with traces of another, less abundant
methane compound, CH4L (Jason).
For GJ 504 b to be so far away, it coordinates with the behaviors seen in our own solar
system. GJ 504 b’s orbit may be 20 AU’s larger in radius than Neptune’s, but they still have
similar chemical makeup. Uranus and Neptune are known for having methane rich atmospheres.
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With the uncertainty of 20 AU’s and based on these two systems, the matching compositions of
these three planets cannot go unnoticed, based on their distance form their stars.
Jupiter and GJ 504 b have fairly different chemical makeups. However, the reason for
this could be largely due to GJ 504 b’s extreme distance from its parent star. A location where
methane compounds where abundant, formed together via one of the two planetary models, and
created the new methaneiol rich planet.
3.2 Meteorological Conditions
Another very important aspect of the atmospheres of Jovian planets is what the gas
compounds that comprise it are doing. The weather of gas giants can be looked at almost the
same way they are on Earth. Our own Earth has an atmosphere where we can measure pressures,
precipitation, temperatures, and storms. Giants have these same features, the only difference is
that theirs are much, much larger compared to Earths and countless times thicker.
In section 3.1, it was already explained how the different zones and belts interact witch
each other due to different pressures to create the stratified groups of bands running latitudinal
across Jupiter. These could be encompassed into meteorological conditions as well based on
how they work. However, not only Jupiter, but gas giants in general have much more to look at
in their thick blankets of gas. Author of the book Cosmos, Giles Sparrow states:
“Along the boundaries between belts and zones, complex and beautiful cloud patterns
called festoons frequently appear, and the movement of different air masses can set up rotating
cells that develop into vast storms” (Sparrow 55).
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These festoons Sparrow talks about are a frequent feature within Jupiter’s atmosphere.
The belts and zones travel around the planet in opposite directions. Therefore, just like when the
pressure systems and cells on Earth meet, they collide and swirl creating vast storms. Upon an
examination of the atmosphere of Jupiter in a photo, these festoons become extremely clear and
are found all over the planet’s outer layer of clouds. These storms can create tremendous winds.
As seen in Figure 3.3, both Cassini and Voyager missions were able to detect great wind speeds
at consistent rates twenty years apart.
Figure 3.3
Festoons really can grow to immense sizes. One perfect example is Jupiter’s famous
Great Red Spot. The Great Red Spot really is just a case of a festoon becoming so large and
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spinning so rapidly it was able to stabilize into a raging storm easily larger than two Earths that
has been raging ever since its discovery.
Astronomers believe another part of the reason that the Great Red Spot has been so
persistent is that it is not like hurricanes here on Earth. Terrestrial hurricanes travel over ground
and lose their energy source, a.k.a. warm ocean water. In Jupiter’s case the Great Red Spot
never really loses its energy. It is believed to be powered by the great heat created from the
immense pressures experienced as you travel deeper into the planet. The rival rotations of the
bands aid in the creating of cyclones as seen Figure 3.4. In addition, since there is no land for
the Great Red Spot to travel on, it wouldn’t lose energy over it, rather than being continuously
powered in the gaseous atmosphere (The Atmosphere).
The Great Red Spot has become one of the most widely studies aspects of Jupiter’s
atmosphere. Writer Jerry Coffey states:
Figure 3.4
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The Great Red Spot on Jupiter is one of the best known features in the Solar System. The
storm is located 22° south of the equator and is larger in diameter than Earth. It is thought
to have been in existence when Giovanni Cassini observed the planet in the 1600s. The
storm rotates in a counter-clockwise motion (See Figure 3.4 as to how these counter-
clockwise motions begin). It has been known to shrink and grow. It has been as large as
40,000 km in diameter. It rotates differentially than the rest of the atmosphere: sometimes
faster and sometimes slower. During its recorded history it has traveled several times
around the planet relative to any fixed position below it (Coffey).
It is completely possible for another gas giant like GJ 504 b to have these same similar
features found on Jupiter. Unfortunately for astronomers, not much is necessarily known about
what sort of weather conditions can be found on GJ 504 b. The planet is believed to have vague
stratified bands like both Saturn and Jupiter. These pressurized systems could almost certainly
have the potential to create great storms and festoons like found on Jupiter.
The different chemical compositions may also play a role in what the meteorological
conditions do. The ammonia compounds in Jupiter’s troposphere may react and move
differently than the mainly methane based compounds of GJ 504 b. One factor GJ 504 b has in
common with Jupiter is the heat is still there. Jupiter gets a majority of its heat from lighting
created from the discharging of ammonia crystals in the troposphere and the heat produced in the
planets inner layers due to the great pressure. However, GJ 504 b is still young and carries a lot
of heat with it. Dr. Michael McElwain, member of NASA’s Goddard Space Flight Center team
stated: "If we could travel to this giant planet, we would see a world still glowing from the heat
of its formation with a color reminiscent of a dark cherry blossom, a dull magenta. Our near-
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infrared camera reveals that its color is much more blue than other imaged planets, which may
indicate that its atmosphere has fewer clouds” (Reddy).
According to astronomers, GJ 504 b has the heat to move clouds and gasses in intricate
storms like Jupiter, but the fewer clouds believed to be lack thereof in the atmosphere may bring
about problems. Jupiter is rich and dense in its cloud structure but GJ 504 b may be much less,
thereby not providing a sufficient amount of gas in order to create effects found in atmospheres
like Jupiter.
3.3 Notable Anomalies
When it comes to studying the heavens, one thing is for certain and it is that nothing is
certain. From the ancient stargazers of the past to the modern accredited astronomers of the day
there have always perplexing questions with unfindable answers. In this day of modern
astronomy, this principle still applies.
Jupiter is one of the most studied planets, outside of Earth, but yet there are still aspects
of it we don’t fully comprehend. Like stated in Chapter 3.2, it is believed Jupiter’s Great Red
Spot is powered by residual heat emitting from the planet’s core, powering the large festoon.
However, this has never been proven. This theory is merely one of the best supported and
accepted. Like Jerry Coffey stated in Chapter 3.1, the Great Red Spot goes through phases of
growth and shrinkage.
On 15 May 2014, NASA released a statement saying the Great Red Spot is actually
believed to be at its smallest size every observed. Ever since the astronomers first attempted to
calculate its size, the measurements have become smaller and smaller. Astronomers believe they
may know of a reason for such a change in a storm hundreds of years old. Amy Simon from the
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NASA Goddard Space Flight Center said, “In our new observations it is apparent very small
eddies are feeding into the storm… We hypothesized these may be responsible for the
accelerated change by altering the internal dynamics and energy of the Great Red Spot.”
The Goddard team plans to continue research in to the storm to confirm their beliefs
(Phillips).
In addition to the phenomena of the Great Red Spot, one mystery that has baffled
astronomers for a long time is the state of Jupiter’s core. Scientists have no idea what is actually
at the center of Jupiter, and have only postulated theories as to what it may. More information
regarding just what the core could be made of can be found in Chapter IV.
Another mystery that astronomers are stumped on is what powers Jupiter’s immense
electromagnetic field. Jupiter’s magnetic field is the largest planetary energy field in the solar
system as seen in Figure 3.5. It takes the tapered shape seen due to the charged particles of the
Sun’s rays, just like Earth’s.
According to the beliefs of modern geology, a liquid metallic core is necessary for the
presence of an electromagnetic field. The composition of Jupiter’s inner core is currently
unknown. There are several proposed theories as to what type of core is hidden under Jupiter’s
clouds. The most widely accepted theory, based upon Jupiter’s very own electromagnetic field,
will be further looked at in Chapter IV.
Electromagnetic fields are also responsible for auroras. Auroras are a fairly common
occurrence on Earth, but they are also commonly found on Jupiter. When charged particles from
the Sun hit the weaker portions of Jupiter’s magnetosphere, they get trapped and spin creating
energy, become excited, and release the energy in the form of visible and ultraviolet wavelengths
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creating a phenomena similar to our own Northern Lights here on Earth (Garrity). Jupiter,
having the largest electromagnetic field of all the planets in our solar system, is also responsible
for creating the largest planetary auroras in the solar system. They have been photographed and
studied by numerous NASA missions.
Figure 3.5*
*Credit by Peter J. Garrity of StarMariner.net
Being so far away and not as extensively studied as other exoplanets, GJ 504 b has not
had much time to really be looked at closely for any unusual anomaly. However, one aspect of it
is its nonconformity with the recognized models of how gas giants formed, as mention in
Chapter I. Both the core accretion model and gravitational instability model only work for
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planets hovering around 30 AU’s from its parent star. Because of this, it is possible to see new
propositions on how gas giants form. There is a good chance of seeing tweaks and adjustments
on our two contending models. Further research may even prove that the gravitational instability
model has been right all along, discrediting the more favored core accretion model. Or perhaps
we may see both models completely rejected based on new developments in the field of
astrophysics with GJ 504 b being the catalyst for a new age of study in the field of planetary and
gas giant formation.
GJ 504 b is significant because it reverberates the old idea that only one thing is for
certain and that is nothing is certain. Discoveries like GJ 504 b are what propel the fields of
astronomy and astrophysics because they cause us to rethink theories we thought to be correct
and cause to constantly have to adapt with each and every new discovery.
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Chapter IV
The Core and Inner Layers
4.1 Under the Troposphere
Gas giants are known for not having a definitive surface. To the less informed, one
would imagine a gas giant’s atmosphere is static and remains as cloud-like formations up until
the theorized core is reached.
However, this is not the case. If you could travel through a gas giant’s atmosphere, you
would not see a stagnant cloud cover of gasses. The deeper you go the physics of the planet
begin to take shape and really have an influence on just what the planet is doing. Great pressures
and heat begin to alter the matter that comprises these atmospheres and transform them into
peculiar forms.
Recall that the composition of Jupiter is almost all hydrogen. The majority of this
hydrogen lies under the belts and zones of its outer atmosphere. Jupiter is large and possesses
great amounts of gas. When small amounts of gas join even larger amounts of gas, they begin to
make a difference in a planet’s composition.
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On Earth, we have a liquid molten outer core and a solid inner core comprised of heavy
elements, mainly iron and nickel. Contrary to what most may logic, the inner core is actually
hotter but remains a solid. This is due to the amount of pressure it is under. The inner core has
almost all of Earth’s mass, 5.98 x 1024 kilograms, pressing down on it. An amount of pressure
like this is so great it will actually force a change in its state of matter. If a metal or rock heats
up to a high temperature, it will begin to melt. The pressure on Earth’s core is so great that it
actually inhibits molecular movement, forcing it to remain in a solid state, as the molecules and
atoms cannot move as freely, yet the outer core remains liquid because there is not enough to
pressure force a change in state of matter.
A similar process is taking place within Jupiter. However, rather than forcing a liquid
state of matter to a solid state of matter, Jupiter’s pressure forces its gaseous hydrogen
atmosphere into the form of a liquid. Despite hydrogen naturally occurring as a gas, Jupiter’s
pressure within its inner layers is so great that it restricts atomic movement, thus forcing it into a
liquid as in Figure 4.1
Figure 4.1*
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…The interior of the planet is mostly liquid hydrogen containing small amounts of
heavier elements. The pressure and temperature are higher than the critical point for
hydrogen, and that means there is no difference between gaseous hydrogen and liquid
hydrogen. If you parachuted into Jupiter, you would fall through the gaseous atmosphere
and notice the density of the surrounding fluid gradually increasing until you were in a
liquid… (Seeds 505).
The actual size and depth of the liquid hydrogen layer is debated. As with most of
Jupiter’s inner layers, it remains a mystery to modern astronomy. Knowing that Jupiter is made
of about 90% hydrogen, astronomers hypothesize the hydrogen layers would become so
compressed as to turn into a liquid form of H2, the hydrogen compound comprising Jupiter.
The possibility of an extremely similar composition may exist within GJ 504 b. GJ 504 b
does have higher amounts of methane compounds as detected by its direct imaging, but what lies
underneath is a mystery. The more methane based Jovian planets, Uranus and Neptune, which
are more similar to GJ 504 b with respect to their semimajor axis and known composition, could
provide a better forecast of what could be inside of GJ 504 b. Uranus and Neptune are still
mainly comprised of hydrogen and helium despite the strong presence of methane compounds,
so perhaps GJ 504 b could be hiding a large layer of hydrogen or H2 underneath its methane
outer shell.
4.2 Further Down
*Figure credit to Nick Strobel
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The further down we venture into the atmosphere of Jupiter, the less certainty there is.
Pressures increase, temperatures, increase, and exotic changes start to happen to the hydrogen
compounds.
The smoking gun for the possibilities of what is this deep in the atmosphere lies in
Jupiter’s giant electromagnetic field. A liquid metal core is necessary for the stabilization of an
electromagnetic field. This comes from the dynamo effect theory that states a rotating body with
a metallic core of convecting matter is necessary for the creation and stabilization of a magnetic
field (Strobel).
The question astronomers might ask would be, if Jupiter is made of mainly hydrogen, a
gaseous and non-metallic element, what is creating the electromagnetic field that requires a
convecting metal?
Astronomers and astrophysicists believe they may have the answer. They believe the
liquid hydrogen from the previous layer gets compressed even further to create a strange
substance known as liquid metallic hydrogen. Planetary formation expert of the California
Institute of Technology, David Stevenson said, “Liquid metallic hydrogen has low viscosity, like
water, and it's a good electrical and thermal conductor… like a mirror, it reflects light, so if you
were immersed in it, you wouldn't be able to see anything” (Coulter).
Refer back to Figure 4.1 to see how compression creates liquid metallic hydrogen. The
pressure is so great it has enough power to overcome the forces holding the electron into the
atom. When the electron is released, it establishes a pool of electrons surrounding all the
hydrogen atoms. This pool of electrons becomes a great conductor of electricity. Astronomers
believe this metallic form of hydrogen is what is generating all of Jupiter’s electromagnetic field
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and satisfies the problem of not having a suitable electric conductor as presented by the dynamo
effect theory.
It is fairly hard to determine just exactly what liquid metallic hydrogen is and how it acts,
despite our basic understanding of it based on our knowledge of physics. Scientists have never
been able to study it in hand as it does not occur naturally on Earth and attempts to create it in a
lab are futile. Under lab conditions, scientists can only mimic the pressures needed to create
liquid-metallic hydrogen for only a short amount of time. Consequently, the amount of time
their hydrogen samples occupy their liquid metallic state is extremely small, less than a second,
which is not a sufficient amount of time in order to study and observe. For now, the
characteristics behind liquid metallic hydrogen largely remain a mystery, despite the wide
presence of it on worlds outside our own.
No one is sure exactly what portion of the inner layers is liquid hydrogen and how much
is liquid metallic hydrogen. One estimation can be found in Figure 4.2, presented by the
Kapteyn Astronomical Institute, however the debate goes on.
Figure 4.2
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There is an extremely high probably of GJ 504 b having a similar inner content as Jupiter.
More than likely, GJ 504 b has inner layer composition of mainly hydrogen (H2), helium,
methane compounds, and other heavier gasses like oxygen, nitrogen, etc.. Should the SEEDS
team further their research into GJ 504 b, we may see a firm establishment of what exactly it is
made of beneath the calm magenta methane troposphere.
However, for the time being, a mainly hydrogen composition is more than likely the case.
Based on the mass and size of GJ 504 b, and provided there was a hydrogen center, the presence
of liquid metallic hydrogen inside of it would almost certainly be guaranteed. Recalling the mass
of GJ 504 b to be roughly four times the mass of Jupiter, or 7.6 x 1027 kilograms, it can easily be
concluded that there would be enough pressure to squeeze out its hydrogen atoms’ electrons to
form the liquid metallic hydrogen soup. According to Figure 4.2, once the inner mantle reached
11,000o Kelvin and experiences pressures of three million standard atmospheres (atm).
With respect GJ 504 b’s inner layers, it can be concluded that it is similar to not only
Jupiter, but all other high mass, high density, hydrogen rich planets.
4.3 Core
Astronomers possess a great deal of certainty on the content of Jupiter’s inner and outer
mantles. There is a firm belief of the liquid hydrogen layer and the following liquid metallic
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hydrogen based on the pressures, temperatures, and the cause for its massive electromagnetic
field.
One thing still eluding astronomers is what makes up the core, or lack thereof, of gas
giants like Jupiter and GJ 504 b. This debate stems back to the argument of which form
planetary creation is responsible for gas giants, the gravitational instability model or core
accretion model. Astronomers are fairly certain the smaller terrestrial planets formed by means
of the core accretion model, or a similar process. There is not much of a debate on those
grounds. Neither of the models are perfect and they both have their problems.
The core accretion model, again, the more widely accepted model in today’s modern
astronomy, argues on the platform based on its namesake. It states a solid core of either rock,
ice, heavy metals, or a composition of all three, formed together to attract and pull in the
hydrogen and helium gasses from the planetary disk left over from the initial formation of the
sun. This model presents strong evidence for a solid core, more than likely of rock and ammonia
or methane ices. Despite the heat, possibly 40,000 degrees Kelvin, according to Figure 4.2, the
ice remains as it is based on the pressure at the center. The ice formations cannot melt, taking
the form of a liquid, because of the pressures pushing down the atoms, restricting entropy in the
core.
Believers in the gravitational instability model would more than likely argue there is a
core of super condensed hydrogen, ices, or other heavier gasses, but not necessarily taking the
shape of solid. A rocky or metallic based core would be out of the question. Since the
gravitational instability model concludes the planet’s disk of material spun rapidly to eventually
fall in on itself due to its own gravity while all the heavier and denser elements sank to the
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bottom. This “bottom” of the planet would be its core. Nonetheless, the idea of a solid core is
nonexistent. A “soup” of elements condensed down and extremely hot is more favorable under
this model. Gemma Lavender of All About Space stated: “A theory surrounding the formation
of giant planets of gas suggests that there is almost definitely a core. This idea is called the
bottom-up theory or core-accretion model. Here, a ten Earth-mass protoplanet formed, which
quickly swept up gas from the primordial disk that formed our Solar System to develop a
massive atmosphere around it and become the gas giant Jupiter (Lavender).”
While the core accretion model recognizes the need for a solid core, even under the
temperatures and pressures of Jupiter’s atmosphere, solids aren’t necessarily solid. The metallic
hydrogen compounds, ices, molten metals, and other varying materials and combine together to
create a somewhat slushy core (Lavener).
Therefore, even as these two models stand differently, they both possess similar
components in the fact that even though the core is “solid” in the core accretion model, it still
possesses semi-liquid traits in certain aspects.
GJ 504 b is a planetary outcast, not clearly fitting into or only fitting certain pieces of
each model. Its mass is sufficient enough to be labeled as a win for the gravitational instability
model, but this model is a requiring millions of years to create planets. Based on the estimates of
GJ 504 b’s age and the times it takes the gravitational instability model to apply to planets, the
numbers would not add up.
With respect to the core accretion model, GJ 504 b is much too massive and much too far
away from its parent star for it to be an effective model of creation. Because of this, it is fairly
hard to determine what is at the center of GJ 504 b. Until further research is done, astronomers
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are sort of left to apply what we know about other gas giants to GJ 504 b. Those applications
being the chances of a similar liquid metallic core or possibly a rocky and/or heavy metal and ice
core must reside there.
Until we can discover what is actually inside the core of at least one Jovian planet, we
may never know. Even at that point, no one can say if the same core characteristics apply to all
other gas giants.
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Chapter V
Conclusion
The discovery of GJ 504 b back in 2013 by the SEEDS team was a groundbreaking
discovery. It shattered the previous belief of how a gas giant like Jupiter and itself could have
formed. I initially set forth to find out what helped to make this planets so different by covering
every possible aspect of this planet. I took into consideration how all these aspects compared to
Jupiter, a standard, well-known, and well-studied Jovian planet. I analyzed the different
characteristics and aspects of each to see what possibilities of differences are hidden.
The first aspect covered was each planet’s appearance. It was clear from the beginning
that these planets differ greatly here. Jupiter is known for its white, brown, and rusted red
appearance while GJ 504 b is making headlines in the astronomical community as the “bubble
gum” planet based on its magenta, purplish color. These color differences are attributed to the
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different chemical compounds found in their outer troposphere. It is clear to see a concurrence
in their chemical makeup, based purely on the visible wavelengths of their outer troposphere is
nonexistent.
I concluded in my research into GJ 504 b’s potential density that it would lay very close
to Jupiter’s. Based on pure speculation and averages, I would personally feel that GJ 504 b
would extremely similar to Jupiter in respect to its mass and volume.
The possibility of a satellite system, either being a moon, ring system or bath, is an
extreme and more than likely possibility. Based on observations of other gas giants, namely our
local Jovian gas giants, the potential for moons becomes clear. GJ 504 b has a mass four times
greater than the most massive planet in our solar system. It would be a spectacle to see a planet
this size with no means.
In addition, along with all having moons, all Jovian planets have a ring system of some
as shown by Figure 2.1. Further extending this logic, a ring system similar to Jupiter’s is again
an almost certainty, especially if GJ 504 has an outer debris field. To conclude, moons and other
similar satellites are an almost guarantee, however, further research an observation can be the
only final say.
In my attempt to pin a number on GJ 504 b’s gravitation pull, I averaged out the densities
of our Jovian planets an assigned it to GJ 504 b, a value I found applicable based on previous
reasoning. Through my calculations I was able to determine that GJ 504 b has an acceleration
due to gravity of 39 meters per second per second, almost 1.6 times more greater than Jupiter. It
is necessary to note these values are built upon reasoning and averages so the actual value may
and more than likely will vary from my produced value.
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I was able to determine there are actually big differences in the chemical makeup
between Jupiter and GJ 504 b based purely on their color. My research produced that the
chemical makeup of each planet’s troposphere is believed to have a large role in the planet’s
visible color. It is known that GJ 504 b was imaged to be a planet largely comprised of methane
compounds, with respect to the troposphere. Jupiter’s hydrogen rich troposphere is what dictates
its well-known color. Based on this reasoning alone it can be easily conclude that GJ 504 b
shares very few similarities with Jupiter’s outer layer. It may however prove to be a better match
to other methane rich planets like Uranus and Neptune.
When looking at atmospheric conditions, there are differences and possibilities for
similarities. Jupiter is a ravenous world of high speed winds, varying pressure zones, and great
storms. GJ 504 b more than likely has similar characteristics but it is believed to be much
calmer. Movement of gas isn’t as active, but the possibility is still largely there for great storms
based upon the heat the planet is putting out. This heat is pure fuel for moving pressure systems
that use heat to create storms like Jupiter’s Great Red Spot.
In Chapter III, I also looked at the possibility of GJ 504 b possessing an electromagnetic
field. The chance of this happening almost independently revolves around the presence of liquid
metallic hydrogen in its inner layers. The liquid metallic hydrogen is solely responsible for
Jupiter’s and all other Jovian planets’. It seems that any planet with a majority composition of
hydrogen (H2) would possess an electromagnetic field proportionally equal to the amount of
liquid metallic H2 present inside of it. More than likely, GJ 504 b would be a mainly hydrogen
body, based on other gas giants, so there is no reason to believe an on ocean of liquid and liquid
metallic hydrogen, and by extent and electromagnetic field, would be present.
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One aspect of not only GJ 504 b, but all gas giant and Jovian planets, that is still a
mystery is their core composition. Astronomers have yet to perform a conclusive test to find out
just what exactly lies at these planets’ centers. There are different beliefs based on different
models of creation, but no one knows for sure. The two current possibilities that exist are a
dense gas and liquid core and a solid, slushy core of a mixture of rock, compressed gasses and
ices.
I originally set out to find out if GJ 504 b shares a sufficient amount of characteristics
that would allow me to determine if GJ 504 b and Jupiter could be the same type of gas giant.
Unfortunately, based upon all my research and findings, I believe they are not similarly sufficient
enough to be thrown into the same category. Although research is still young for GJ 504 b, the
facts presenting themselves now tell me they are very different. The share very different
tropospheric compositions, their size and mass do rival each other, but not close enough to allow
a good comparison, the probable origins of their creations are far too different based upon their
distance from their stars and meteorological conditions are polar opposites in terms of gas giants.
The only aspects concurring with each other like the potential for an electromagnetic field and
believed hydrogen inner composition are common among too many other gas giants to really be
point out as significant.
Jupiter and GJ 504 b are two ends of the same stick. They are two amazing celestial
bodies that are unique in their own ways, but unique and unalike is how I believe they should
remain based upon my research and conclusions.
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