Sedna- The hidden treasure of the Solar System
A. Definition of Sedna
Planet Sedna is a distant and mysterious world located in the outer reaches of our
Solar System. It is the most distant known object in the Solar System and has been classified as
a dwarf planet. It was discovered in 2003 by Michael E. Brown, who later named it “Sedna”
after the Inuit goddess of the sea, Sidne. Sedna is believed to be the remnant of the Early Solar
System. Exactly two decades later, Sedna has again caught the limelight of astronomers all
around the World. Due to its mysterious nature, Sedna has always confused astronomers until now.
Sedna is a dwarf planet by the International Astronomical Union (IAU). It was officially
classified as a dwarf planet in 2008, making it the third object recognised by the IAU.
It is located beyond the orbit of Neptune and is believed to be part
of the Kuiper Belt, a region of icy bodies beyond the orbit of Neptune.
B. Overview of Sedna's discovery
The discovery of Sedna has significantly impacted the field of astronomy and astrophysics.
Sedna is the most distant object ever observed in the Solar System, and its discovery has provided
scientists with valuable insights into the formation and evolution of the outer Solar System.
Sedna's discovery has also helped to confirm the existence of the hypothesised Oort Cloud,
a vast spherical shell of icy objects that surrounds the Solar System.
Sedna's orbit is highly eccentric, and its perihelion is much farther from the Sun than
any other known object in the Solar System. This suggests Sedna is a member of the Oort Cloud,
and its discovery has provided further evidence to support the hypothesis.
Sedna's discovery has also led to the development of new theories about the formation of the Solar
System. Its highly eccentric orbit suggests that it may have been affected by the gravitational
pull of a passing star, which could have caused it to be flung out to its current location.
This has led to the hypothesis that the Solar System may have been formed from the gravitational
interaction of multiple stars. Now, this is where it gets interesting for astronomers.
Sedna’s bizarre behaviours may have risen due to various external factors. Sedna's discovery has
also helped to shed light on the mysterious Planet Nine. Its highly eccentric orbit is
similar to that of other objects hypothesised to be part of Planet Nine's gravitational influence.
This suggests that Planet Nine may indeed exist, and its discovery could help to unlock
the mysteries of the outer Solar System.​​ So many secrets trapped within the unknown
knowledge of Sedna. Imagine if there was a space exploration of this Dwarf. Such
an event would immensely benefit astronomers in their fields of study. We started talking
about Sedna all the way down to Planet Nine and the sun’s interaction with other stars.
Let’s restrict ourselves to Sedna for now. Planet Nine can wait for now.
II. Physical Characteristics
Sedna is a giant, reddish-brown dwarf planet located in the Kuiper belt, beyond the orbit
of Neptune. The surface of Sedna is believed to be composed of a mixture of water ice,
methane ice, and tholins, which are organic compounds created by ultraviolet radiation.
It is estimated to have a surface temperature of around -240°C. The surface is believed to be
covered in craters, ridges, and other features, which are thought to have been created by impacts
from other objects in the solar system. Its surface is covered in a thick layer of methane
and nitrogen ice, which gives it its reddish-brown hue. Its atmosphere comprises a thin layer of
methane, nitrogen, and carbon dioxide. It has a prolonged rotation period of about 20 days.
Sedna's rotation is also a mystery. It is believed to be rotating very slowly, taking
almost ten days to complete one rotation, which is much slower than the other planets beyond Neptune.
Also, its rotation is unsynchronised with its orbit. This suggests that it may have
been affected by some external force, such as a passing star or another planet.
A. Size and Mass It has a diameter of approximately
1,000 kilometres, around three-quarters the size of Pluto, making it the fourth-largest
known trans-Neptunian object. You may be wondering what Trans-Neptunian objects are. Trans-Neptunian
objects (TNOs) are small celestial bodies that orbit the Sun at a distance greater than Neptune.
They are located in the Kuiper Belt, a region of the Solar System beyond
the orbit of Neptune. TNOs include dwarf planets, comets, and other small bodies.
C. Orbital Path
The mysteries of Sedna are numerous and varied. For one, its orbit is highly unusual. It is one
of the most distant objects in the Solar System, and its orbital path is highly inclined to the
plane of the Solar System, which means that it is not in the same plane as the other planets.
Its orbit is much more elongated than those of the other planets.
Sedna is located in the Kuiper Belt, a region beyond the orbit of Neptune that is home to
many icy bodies. Its orbital path is highly elliptical, with a perihelion (closest approach
to the Sun) of 76.1 Astronomical units and an aphelion (farthest distance from the Sun) of 937
Astronomical units. It takes about 11,400 years for Sedna to complete one orbit around the Sun.
Sedna's orbit is also vital for understanding the dynamics of the outer Solar System and
the possible presence of a giant, undiscovered planet beyond Neptune.
III. Theories of Origin
The origin of Sedna is also a mystery. It is believed to be a member of the Kuiper Belt, a
region of icy bodies beyond Neptune, but its exact origin is unknown. The Sun’s gravity may have
captured it, or it may have been formed in the outer Solar System and then captured by the Sun.
Some astronomers believe it is a dwarf planet, while others think it is a giant comet captured by
the Sun's gravity. Still, others believe it is an escaped moon of Neptune that was ejected from the
planet's orbit due to gravitational interactions with other objects in the outer solar system.
Following are some theories predicting the origin of Sedna.
1. Capture Theory: This theory suggests that Sedna was once a part of a much larger body,
such as a planetesimal or a dwarf planet, which was captured by the gravitational pull of the Sun.
2. The Capture-and-Ejection Theory suggests that Sedna was once part of a much larger body
captured by the gravitational pull of a passing star. The star ejected Sedna from its orbit,
sending it into the solar system’s outer reaches. 3. The Planet Formation Theory suggests that Sedna
formed from the same cloud of gas and dust that constructed the other planets in the Solar System.
4. The Migration Theory suggests that Sedna formed in the Solar System’s outer reaches and then
migrated inward due to gravitational interactions with other objects in the Solar System.
5. Capture from Interstellar Space Theory: This theory suggests that Sedna was captured
from interstellar space by the gravitational pull of the Sun.
B. Composition Sedna is a rocky
core surrounded by a mantle of water ice. Is it impossible? At first thought, it seems to be, but
space is mysterious. You know what they say; It is what it is. The centre comprises silicate rocks,
such as olivine, pyroxene, and possibly some iron-nickel metal. The mantle is composed of
a mixture of water ice, methane ice, and ammonia ice. Another mystery of Sedna is its composition.
It is believed to be composed primarily of rock and ice, but its exact composition is unknown. Its
reddish hue suggests that it may contain organic compounds, but this has yet to be confirmed.
B. Potential for Habitability
Sedna is located in the Solar System’s outer reaches and is too far from the
Sun to be considered habitable. It is estimated to have a surface temperature of around -240°C,
which is far too cold for any known life form to survive. Additionally, Sedna has no atmosphere
and is exposed to extreme radiation levels, making it even less likely for any form of life to exist
there. Despite its inhospitable environment, some scientists have suggested that there may
be a subsurface ocean of liquid water on Sedna, potentially providing habitat for extremophiles.
However, the conditions on Sedna are still too extreme for any known form of life to survive,
and further research is needed to determine if the planet could potentially be habitable. But by
creatures, we are referring to the large ones—the ones comparable to or more prominent than human
beings. There still may be some tiny organisms which may survive Sedna’s extremes easily.
B. Impact of Sedna's Discovery
Sedna is an intriguing and mysterious world still being studied by astronomers. Its unique orbit
and composition make it an essential object for understanding the formation of the Solar System.
It is also of interest due to its unusual colour, which may provide clues about the
composition of the outer Solar System. As we continue learning more about Sedna,
it will undoubtedly remain an essential part of our understanding of the Solar System.
The mysteries of Sedna are likely to remain unsolved for some time.
Its unusual orbit and composition make it a fascinating object to study, and
its origin is likely to remain a mystery for many upcoming years. Nevertheless, the study of Sedna
is likely to provide valuable insights into the formation and evolution of the outer solar system.