Solar System, a topic of exploration which is vast and mysterious in itself, and perhaps this is because in spite of being our home town, it is so big that we have not been able to understand it 100%. In Solar System our parent star SUN has 8 planets revolving in its orientational orbit and out of that the third rocky habitable planet means EARTH is our home, where I am sitting and writing this blog… really fascinating!
Solar System sounds like such a familiar name, right? Do we know it completely? You are saying right, we know about the parent star Sun and the 8 planets revolving around it and a little about Pluto, some asteroids, some moons, that’s the solar system, right? Not actually, and today we are going to talk about the same topic which everyone knows but is under-rated, that is dwarf planets, you must know that Pluto is placed in the category of dwarf planets because it is small and its orbit is not like other planets, not only Pluto, there are more than 100 dwarf planets, big and small, however, the dwarf planets that we are going to talk about today are all unique planets, and you will also know how big our solar system is in size.
Our solar system is spread over 200000 AU (1AU = 150 million kilometers) and this makes up 1.5 light years, actually it is very big, our solar system is much bigger than we think, and we might be thinking that Pluto is very far away, which it is only 39 AU (5.5 billion km) away, it might seem a lot, right?, Sedna the farthest dwarf planet in our solar system at aphelion is 937 AU (140 billion km) away from sun. It’s the game of distance. So let’s start this journey of dwarf planets.
(* comparison of 6 dwarf planets distance from sun)
1. Pluto
Pluto, once hailed as the ninth planet on the solar system’s edge, now holds the title of dwarf planet. This reclassification in 2006 sparked debate, but Pluto’s captivating nature remains. Let’s delve deeper into this intriguing world:
Size and a Surprisingly Active Surface: Though not a planet, Pluto is the undisputed king of dwarf planets. Its diameter stretches roughly 1,477 miles (2,377 kilometers), making it a little over one-sixth the size of Earth and roughly half the width of the continental United States. The 2015 New Horizons mission unveiled a surprisingly dynamic surface. Towering icy mountains, some exceeding 6,500 feet (2,000 meters) in height, cast dramatic shadows. Vast nitrogen glaciers flow like Earth’s rivers, and smooth, dark plains, likely composed of frozen organic materials, hint at a past rich in geological activity. This diversity suggests Pluto’s internal processes may still be shaping its surface.
A Thin Atmosphere with Big Mood Swings: Pluto’s thin atmosphere, primarily composed of nitrogen with traces of methane and carbon monoxide, adds another layer of intrigue. Unlike Earth’s stable atmosphere, Pluto’s undergoes dramatic transformations due to its highly elliptical orbit. As Pluto ventures farther from the sun, on its 30 to 49 AU elliptical journey (AU = distance between Earth and the sun), temperatures plummet (averaging -387°F or -232°C). This extreme cold forces the nitrogen atmosphere to condense and freeze onto the surface, leaving behind a hazy blue sky. Conversely, as Pluto swings closer to the sun (perihelion) at around 30 AU, these frozen ices sublimate, transforming back into gas and returning to the atmosphere.
A Nomadic Path and the Kuiper Belt: Pluto’s orbit is unlike any planet’s. It’s highly elliptical, causing its distance from the sun to vary greatly. At aphelion (farthest point), Pluto reaches a staggering 49 AU, while at perihelion it ventures inward to 30 AU. Interestingly, for a significant portion of its 248-year orbit, Pluto actually gets closer to the sun than Neptune. However, a stable orbital resonance ensures they never collide. Pluto resides within the Kuiper Belt, a vast icy realm beyond Neptune teeming with thousands of leftover rocky and icy objects from the solar system’s formation.
Dwarf Planet Status and Comparisons with Peers: Pluto’s dwarf planet classification stems from its size and the discovery of other similar objects in the Kuiper Belt. Eris, another dwarf planet, is even more massive than Pluto, though slightly smaller in volume. These discoveries led the International Astronomical Union to define a planet in 2006, with one key criterion being that a planet must have “cleared the neighborhood around its orbit.” Sharing its orbital space with numerous Kuiper Belt objects, Pluto doesn’t meet this requirement.
2. Eris
Eris, named after the Greek goddess of discord, reigns supreme as the most massive dwarf planet currently known in our solar system. Despite its dethronement from “planet” status in 2006, Eris remains a captivating world with unique characteristics:
Size and a Surface Shrouded in Mystery: Eris boasts a diameter of about 2,326 kilometers (1,445 miles), making it slightly smaller than Pluto but packing a heavier punch. However, due to its immense distance and faintness, detailed observations of its surface are limited. Scientists believe it likely possesses an icy mantle with a rocky core, similar to Pluto. There are hints of surface features like methane ice patches and potentially some variations in color, but much remains unknown.
A Temperamental Atmosphere (When It Has One): Unlike Pluto’s consistently thin atmosphere, Eris’s atmosphere seems to be a much more transient affair. Eris’s extreme elliptical orbit, ranging from a scorchingly close 34 AU (astronomical units) at perihelion to a frigid 96 AU at aphelion, plays a crucial role. At its farthest reaches, the temperatures plummet so drastically that any potential atmosphere condenses and freezes onto the surface. As Eris ventures closer to the sun, these ices may sublimate, creating a temporary tenuous atmosphere of methane and nitrogen.
A Nomadic Path in the Scattered Disc: Eris’s orbit is far more eccentric than Pluto’s. This eccentricity places Eris not within the confines of the Kuiper Belt, but rather in a more sparsely populated region called the scattered disc. Here, icy objects travel on highly tilted and elliptical paths, influenced by the gravitational pull of Neptune. Eris’s aphelion distance of 96 AU makes it one of the farthest known objects in our solar system, taking a staggering 557 years to complete a single orbit.
Dwarf Planet Champion and a Crowded Neighborhood: Eris’s classification as a dwarf planet is due in part to its discovery alongside other large objects in the Kuiper Belt and scattered disc. While the most massive, Eris isn’t alone in its reign. Pluto, though slightly less massive, is larger in volume. There’s also Haumea, known for its unusual, elongated shape, and Makemake, with its surprisingly reflective surface. The discovery of these dwarf planets led to the International Astronomical Union’s refined definition of a planet in 2006.
Beyond the Basics: A Moon and a Possible Ring: Eris isn’t completely solitary. It has a single known moon, Dysnomia, named after the Greek goddess of lawlessness, Eris’s daughter. Dysnomia is a much smaller companion, estimated to be only about 166 kilometers (103 miles) in diameter. There’s even some tentative evidence suggesting the presence of a faint ring system around Eris, though further observations are needed to confirm this.
3. Haumea
Haumea, named after the Hawaiian goddess of childbirth and creation, stands out among dwarf planets for its unusual shape and intriguing characteristics. Let’s delve into the mysteries surrounding this fascinating world:
The Oddly Shaped Champion: Unlike the spherical Pluto or the more rounded Eris, Haumea boasts a remarkably elongated shape, resembling a giant rugby ball. Its longest axis measures about 2,322 kilometers (1,443 miles), while its shortest is roughly 1,138 kilometers (707 miles). This unique form is likely due to its rapid rotation, which scientists believe could be a result of a violent collision in its past.
A Surface Marked by Ice and Intrigue: Haumea’s surface composition is believed to be a mix of rock and ice, with a mantle of water ice likely covering most of its body. However, unlike Pluto’s vast nitrogen glaciers, Haumea appears to have patches of water ice rich in crystals. There’s also evidence of possible organic materials on its surface, hinting at a complex geological history. Unfortunately, the details remain unclear due to Haumea’s distance and the limitations of current observations.
A Thin and Temperamental Atmosphere (Maybe): Similar to Pluto’s atmosphere, Haumea likely possesses a thin atmosphere composed primarily of water vapor. However, due to its even greater distance from the sun and colder temperatures, the existence and composition of Haumea’s atmosphere are even more uncertain. The extreme elliptical nature of its orbit, ranging from 34.95 AU at perihelion to 51.48 AU at aphelion, could potentially lead to similar atmospheric variations as seen on Pluto, where ices condense and freeze onto the surface at aphelion.
A Nomadic Dance Around the Sun: Haumea shares the Kuiper Belt with Pluto, a vast region beyond Neptune populated by icy and rocky leftovers from the solar system’s formation. However, Haumea’s orbit is far more eccentric than Pluto’s. This eccentricity takes Haumea on a 285-year journey around the sun, with significant variations in distance. At perihelion, it basks in the sun’s warmth at a distance of 34.95 AU. Conversely, at aphelion, it ventures to a frigid 51.48 AU, highlighting the dramatic temperature swings it experiences.
A Dwarf Planet Among Peers: Haumea’s classification as a dwarf planet stems from its size and the discovery of other similar objects in the Kuiper Belt. While not as massive as Eris, Haumea is larger than Pluto in some dimensions. It shares the company of Pluto and Makemake, both dwarf planets with intriguing characteristics. The discovery of these objects, along with the criteria for a planet needing to “clear the neighborhood around its orbit,” led to the International Astronomical Union’s reclassification of Pluto in 2006.
4. Makemake
Makemake, named after the Rapa Nui creation god, holds the title of the second-largest dwarf planet in the classical Kuiper Belt — a realm of icy and rocky objects beyond Neptune. Despite its distance, Makemake offers a glimpse into the fascinating worlds that reside in the outer reaches of our solar system:
Size and a Surprisingly Reflective Surface: Makemake, with a diameter of approximately 1,430 kilometers (890 miles), is roughly two-thirds the size of Pluto. While smaller than its dwarf planet neighbors, Makemake holds a surprising distinction — it’s the brightest object in the Kuiper Belt after Pluto. This high reflectivity is likely due to a surface rich in frozen methane and ethane ices, which are highly reflective at certain wavelengths of light.
A World of Ice and Mystery: Scientists believe Makemake’s surface is composed primarily of rock and ice, with a mantle of nitrogen, methane, and ethane ices. Observations suggest the presence of darker, reddish areas alongside the bright, reflective patches, hinting at a more complex surface composition. However, the details remain a mystery due to the limitations of current telescopes and Makemake’s immense distance.
A Thin and Elusive Atmosphere (Perhaps): The existence of a significant atmosphere around Makemake is a topic of debate. While some studies suggest a very thin atmosphere composed primarily of nitrogen, others haven’t been able to detect one definitively. The extreme coldness of Makemake’s environment, with average temperatures around -238°C (-396°F), means any potential atmosphere could condense and freeze onto the surface. Future observations may shed light on the nature and presence of an atmosphere around this dwarf planet.
A Nomadic Path in the Kuiper Belt: Makemake, like Pluto and Haumea, resides within the Kuiper Belt. However, its orbit is quite eccentric, taking it on a 306-year journey around the sun. This elliptical path brings Makemake as close as 38 AU (astronomical units) at perihelion and as far as 53 AU at aphelion. These dramatic variations in distance from the sun likely influence the behavior of any potential atmosphere and the overall surface temperatures.
A Dwarf Planet Among Rivals: Makemake’s classification as a dwarf planet is a result of its size and the discovery of other large objects in the Kuiper Belt. While the second-largest in the classical Kuiper Belt, it faces stiff competition. Eris holds the crown for the most massive dwarf planet, while Pluto boasts a larger diameter. The discovery of these dwarf planets, along with the requirement for a planet to have “cleared the neighborhood around its orbit,” led to Pluto’s reclassification in 2006.
5. Gonggong
Gonggong, named after the Chinese water god associated with chaos and floods, is a relatively new addition to the dwarf planet club. Discovered in 2007, this distant world continues to hold many secrets. Let’s delve into what we know about Gonggong:
Size and a Probable Spheroid: While a precise measurement remains elusive, Gonggong is estimated to be between 1,129 and 2,524 kilometers (701 and 1,574 miles) in diameter. This range places it among the top five largest known trans-Neptunian objects (objects beyond Neptune’s orbit). Due to its distance, detailed observations are challenging, but scientists believe Gonggong is likely spherical, unlike the oddly shaped Haumea.
A Surface Shrouded in Mystery: Unfortunately, the details of Gonggong’s surface composition remain largely unknown. However, based on its reflectance properties, astronomers suspect the presence of frozen methane on its surface. Additionally, the reddish hue observed hints at the presence of organic compounds called tholins, which are common in icy objects across the solar system. Future missions with more advanced telescopes may provide a clearer picture.
A Thin and Elusive Atmosphere (Perhaps): The existence of an atmosphere around Gonggong is a topic of speculation. Given its immense distance from the sun and frigid temperatures (estimated to be around -219°C or -362°F), any potential atmosphere would likely be very tenuous and could condense onto the surface. However, the possibility of a transient methane atmosphere similar to Pluto’s cannot be entirely ruled out.
A Nomadic Path in the Scattered Disc: Unlike Pluto and Makemake, which reside within the Kuiper Belt, Gonggong belongs to the scattered disc. This region beyond Neptune is far less populated and has objects with more eccentric and inclined orbits. Gonggong’s highly elliptical orbit takes a staggering 554 years to complete and ranges from a scorchingly close 33.7 AU (astronomical units) at perihelion to a frigid 100.68 AU at aphelion. These dramatic swings in distance from the sun likely play a role in the behavior of any potential atmosphere.
A Dwarf Planet Among Peers: Gonggong’s classification as a dwarf planet stems from its size and its location in the scattered disc. While not the largest dwarf planet, it rivals Pluto in terms of diameter. The discovery of Gonggong and other large objects in the Kuiper Belt and scattered disc played a part in the International Astronomical Union’s refined definition of a planet in 2006, which included the requirement for a planet to have “cleared the neighborhood around its orbit.”
6. Sedna
Sedna, named after the Inuit goddess of the sea, holds a unique place in our solar system. This distant dwarf planet, discovered in 2003, boasts an extreme orbit and a mysterious existence:
Size and a Probable Icy Composition: Sedna’s estimated diameter ranges from 915 to 1,800 kilometers (570 to 1,120 miles), placing it among the top ten largest known trans-Neptunian objects. Due to its immense distance, precise measurements are challenging. However, scientists believe Sedna is likely composed primarily of rock and ice, similar to other icy objects in the outer solar system.
A Surface Tinged with Red and Mystery: Observations of Sedna’s surface reveal a surprisingly reddish hue, similar to Mars. This coloration could be due to the presence of organic molecules called tholins, which are common on icy objects exposed to sunlight. However, the details of Sedna’s surface composition remain largely unknown. The extreme distance makes it difficult to discern any surface features with current telescopes.
A Nonexistent Atmosphere (Likely): Given Sedna’s immense distance from the sun (between 76 AU and 936 AU at perihelion and aphelion, respectively) and frigid temperatures (estimated to be around -240°C or -400°F), the presence of a significant atmosphere is highly unlikely. At such extreme distances, any potential atmospheric gases would likely condense and freeze onto the surface.
A Nomadic Path Unlike Any Other: Sedna’s orbit is unlike any other dwarf planet or planet in our solar system. It follows a highly eccentric and inclined path, taking a staggering 11,400 years to complete a single revolution around the sun. This extreme eccentricity brings Sedna incredibly close to the sun at perihelion (closer than Pluto!) and then flings it far out into the distant reaches of the solar system at aphelion, making it one of the farthest known objects.
A Dwarf Planet Among Peers, But a Solitary One: Sedna’s classification as a dwarf planet is due to its size and its location in a detached region of the Kuiper Belt. While not the largest dwarf planet, it rivals Pluto in terms of diameter. However, unlike Pluto, which resides in a more populated region of the Kuiper Belt, Sedna is a solitary world. The vast distances involved and its unique orbit set it apart from other dwarf planets.
