What Are The Dwarf Planets In Our Solar System
Dwarf planets Pluto and Ceres were already known becoming dwarf planets was merely a matter of classification. Eris and several other dwarf planets were discovered or announced in 2005. Ceres is named for the Greco-Roman goddess of grain her name is the origin of the word cereal. Pluto was the Greco-Roman ruler of the underworld.
Eris is in a long elliptical orbit that takes 557 Earth years. Eris is named for the Greek goddess of discord. Eris has a satellite Dysnomia. Dysnomia is named for the mythical daughter Eris, a demon of lawlessness.
Makemake and Haumea are dwarf planets named for Polynesian deities. Makemake was discovered in 2005, shortly after Eris, and classified as a dwarf planet in 2008. Makemake has frozen nitrogen on its surface, and it orbits the sun every 310 years. Makemake does not have any known moons.
Haumea is a dwarf planet in the Kuiper belt. Rotating every four hours, it is one of the fastest rotating bodies in the solar system. This rapid rotation may explain Haumeas ovoid shape it would be round if not for the spin of the body forcing it into an oval. Haumea has two moons of its own, Hiaka and Namaka. The name Haumea comes from the Hawaiian goddess of fertility and childbirth. The two moons, discovered in 2005, are daughters of Haumea in Hawaiian mythology.
Is this dwarf planet a cubewano?
Dwarf Planets In The Solar System
Since the discovery of Ceres, the number of dwarf planets in the solar system has grown. However, there is actually no agreed upon definition of what a dwarf planet is, and so the number of dwarf planets varies depending on who you ask. When the International Astronomical Union defined what a planet is, there were ten objects that were reclassified as dwarf planets. That included Ceres, Pluto, and Eris, along with seven others. If we consider objects similar in size to these objects to be dwarf planets, the number of known dwarf planets in the solar system grows to 120. Although it is now easy to identify whether an object is a planet or not, there is no defined distinction between dwarf planets and spherical asteroids. Thus, there is no defined number of dwarf planets in our solar system, and depending on who you ask, the numbers range from as low as five to as high as 120.
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Dwarf Planets Reveal Neptunes Orbital Origins
Scientists have always known about this resonance, but it was Malhotra who realized its significance. In a 1995 paper, Malhotra calculated that the only way Neptune and Pluto could have ended up in this resonance was if they both had formed closer to the Sun, then migrated out.
Scientists theorize that in the early days of the solar system, the gas giants, Jupiter, Saturn, Neptune, and Uranus, migrated inward toward the Sun and knocked out leftover debris. This gravitational push on planetary debris ended up changing the planets orbits as well, sending Neptune farther out. Neptunes gravitational force encountered Plutos, and the two bodies pushed and pulled at each other until they fell into a resonance orbit. Astronomers detected the same effect in other bodies, including a new dwarf planet announced to the world this year.
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Dwarf Planets Are As Complex As Regular Planets
When the New Horizons probe passed by Pluto more than a year ago, scientists found a complex system with areas of geologically young surface and evidence of active geology. Pluto, the images revealed, wasnt just a chunk of rock orbiting in space. Even I underestimated what we would find, said Alan Stern, principal investigator of the New Horizons mission.
Pluto continues to stun scientists with its unexpected surface features, but its newly revealed complexity is just the beginning. Makemake has no atmosphere. Haumea spins faster than any other known large object in the solar system. Eris might have a thin, icy surface. Ceres hosts mysterious bright spots.
The fact that these objects can be every bit as complicated as terrestrial planets is a headline, Stern said. It should be written in as big a point size as we can write it, because it was completely unexpected.
The Changing Landscape Of The Solar System
The object Tombaugh had discovered was named Pluto, a name officially adopted by the American Astronomical Society, the Royal Astronomical Society in the UK and the IAU. It is a frigid world, billions of kilometres from Earth, and 30 times less massive than the then-smallest known planet, Mercury. But Pluto was not alone. It was found to have five satellites. The largest, Charon, was discovered in 1978. The smaller four were discovered using the Hubble Space Telescope in 2005, 2011 and 2012 and officially named Nix, Hydra, in early 2006 , Kerberos and Styx in 2013 by the IAU.
The view of our Solar System’s landscape began to change on August 30, 1992 with the discovery by David Jewitt and Jane Luu from the University of Hawaii of the first of more than 1000 now known objects orbiting beyond Neptune in what is often referred to as the transneptunian region. More generally these bodies are often simply labelled as Trans-Neptunian Objects .
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Dwarf Planets Are Prolific
Pluto holds a special place in the Internets collective heart but may not be so special in the solar system. Currently, there are six dwarf planets officially designated by the IAU: Pluto, Ceres, Eris, Makemake, Haumea, and 2015 RR245, discovered in July. Since scientists started looking deeper into the Kuiper belt, they have found at least 20 more similarly sized objects, Sheppard said.
And there may be dozens more out there. We discovered that dwarf planets are the most populous class in the solar system, Stern said. Other solar systems may be like ours, too, he added.
This population revelation, along with the surprising geological and atmospheric complexity found on dwarf planets, means that the field could be at the very beginning of a paradigm shift and a revolution, Stern said. Perhaps, he continued, its the classic large planets that are the oddballs of planetary formation.
He wonders, Whos the misfit now?
JoAnna Wendel, Staff Writer
Correction, 18 August 2016: This post was updated to reflect that dwarf planets may be common in other solar systems.
Citation:
Wendel, J. , Six things dwarf planets have taught us about the solar system, Eos, 97, . Published on 17 August 2016.
The Current Dwarf Planets In Our Solar System
After the 2006 General Assembly of IAU and their acceptance of this new category, three celestial bodies have been listed as dwarf planets: Pluto, Ceres, and Eris.
Later in 2008, Haumea and Makemake were also announced as dwarf planets in an IAU press release, even though it couldnt be proved at the time.
Today, these are the only five dwarf planets accepted by the International Astronomical Union. Lets see some details regarding them.
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Ceres Tells Us Something About Icy Moons
The bright and large Occator crater on Ceres may have an ocean beneath it.
Ceres has lots of water in it. Because of its size, this water is most likely frozen now. The brines that flow on its surface serve as evidence of this. Also, the Dawn mission discovered carbonates which could be evidence of a large ocean on this dwarf planet.
With the discovery of ammonia and carbonates, Ceres holds a lot of similarities with icy moons like Europa, Enceladus, and Titan. Ceres also shows cryovolcanism just like the icy ocean world of Enceladus. Because of its large amount of water ice, Ceres can be as potentially habitable as the famous icy moons.
Is Earth A Dwarf Planet
That means that according to the definition of the International Astronomical Union, the Earth cannot technically be considered as a planet and that it is, in fact, a dwarf-planet. ⦠There were seven earth sized objects discovered in orbit around an ultracool dwarf star forty light years away using this method.
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List Of Possible Dwarf Planets
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The number of dwarf planets in the Solar System is unknown. Estimates have run as high as 200 in the Kuiper belt and over 10,000 in the region beyond.However, consideration of the surprisingly low densities of many large trans-Neptunian objects suggests that the number of dwarf planets may be much lower, perhaps only nine among bodies known so far. The International Astronomical Union defines dwarf planets as being in hydrostatic equilibrium, and notes five bodies in particular: Ceres in the inner Solar System and four in the trans-Neptunian region: Pluto, Eris, Haumea, and Makemake. Only Pluto and Ceres have been confirmed to be in hydrostatic equilibrium, due to the results of the New Horizons and Dawn missions. Eris is generally assumed to be a dwarf planet because it is similar in size to Pluto and even more massive. Haumea and Makemake were accepted as dwarf planets by the IAU for naming purposes and will keep their names if it turns out they are not dwarf planets. Smaller trans-Neptunian objects have been called dwarf planets if they appear to be solid bodies, which is a prerequisite for hydrostatic equilibrium: planetologists generally include at least Gonggong, Quaoar, Sedna and Orcus.
More Interesting Dwarf Planet Facts
Its time to round off our post but before we go, here are a few more interesting dwarf planet facts to tie things off. We hope youve enjoyed our post, and maybe even found it a little educational!
- The second-largest object in the asteroid belt, Vesta, may have been a dwarf planet once. However, it is no longer in hydrostatic equilibrium now because of impacts.
- Triton and Phoebe were also probably dwarf planets in the past. However, they are no longer orbiting the Sun as they were captured by Neptune and Saturn respectively.
- Pluto and its largest moon, Charon, could be a double dwarf planet. This is still being debated since there is no formal definition of a double/ binary dwarf planet yet.
- Charon and Pluto are mutually tidally locked to each other. With mutual tidal locking, both objects keep the same face toward the other. The Earths moon is another example of a tidally locked body. Our planet, however, is not tidally locked to it.
- In 2015, the Dawn spacecraft and New Horizons mission studied the systems of Ceres and Pluto respectively. So far, no other spacecraft has visited the other dwarf planets.
- Each dwarf planet is unique. Firstly, Ceres has mysterious bright spots. Pluto has a heart-shaped surface and Haumea is a fast-spinning large body. Makemake has a volatile surface, while Eris, the farthest, may have an icy surface.
If you liked our post on Dwarf Planet facts, why not check out our post on 50 incredible space facts!
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What Makes A Dwarf Planet Different From A Planet
The term dwarf planet was coined by Alan Stern, a famous planetary scientist, when he introduced the three possible ways of categorizing planets: classical planets, such as Earth and Mars, dwarf planets like Pluto, and satellite planets, such as the Moon.
The term has been used to describe planets that are too small to be listed as full-fledged planets but too large to be considered asteroids or any other smaller celestial objects. In 2006, the term dwarf planets was adopted by the International Astronomical Union IAU, and here is how.
In January 2005, a new space object was discovered Eris. At first, it was considered more massive than Pluto, and for that reason, it was listed as the tenth planet in our solar system. A colossal controversy soon started, as not all scientists agreed with this new addition to the planets list.
The debate that followed was intense, and it came to an end during the IAU General Assembly in August 2006, when Resolution 5A: Definition of planet’ was introduced.
According to this resolution, all celestial bodies can be divided into three categories, as follows:
As reported by the International Astronomical Union, a planet is any celestial object orbiting around the Sun with enough gravity to overcome rigid body forces to pull its mass into a round shape.
This state is known as hydrostatic equilibrium, and the celestial object can clear its orbital path so that no other smaller bodies can be found near it.
Size Of The Dwarf Planets
The largest dwarf planet is Pluto, followed by Eris, Makemake, Haumea, and Ceres being the smallest dwarf planet. Just slightly smaller in size than Pluto, Eris is the most massive of them all.
The order of the dwarf planets from closest to the Sun outwards is Ceres, Pluto, Haumea, Makemake, and Eris. Being the farthest, Eris is about 96.4 astronomical units from the Sunalmost 14 billion km away.
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True Colour Image Of Pluto
Credits: By NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Alex Parker â , Public Domain, Link
Three years after NASAâs New Horizons spacecraft gave humankind our first close-up views of Pluto and its largest moon, Charon, scientists are still revealing the wonders of these incredible worlds in the outer solar system. Marking the anniversary of New Horizonsâ historic flight through the Pluto system on July 14, 2015, mission scientists released the highest-resolution color images of Pluto and Charon. These natural-color images result from refined calibration of data gathered by New Horizonsâ color Multi-spectral Visible Imaging Camera . The processing creates images that would approximate the colors that the human eye would perceive, bringing them closer to true color than the images released near the encounter. This image was taken as New Horizons zipped toward Pluto and its moons on July 14, 2015, from a range of 22,025 miles kilometers. This single color MVIC scan includes no data from other New Horizons imagers or instruments added. The striking features on Pluto are clearly visible, including the bright expanse of Plutoâs icy, nitrogen-and-methane rich âheart,â Sputnik Planitia.
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Planets vs. dwarf planets
Dwarf planets are worlds too small to be considered planets but too large to fall into other categories. Recent observations and discoveries have helped scientists understand planetary systems, which lead to a new definition of the term.
The IAU defines a planet as a celestial body that:
1. Orbits the sun
2. Is large enough to be rounded by its own gravity
3. Is large enough to have cleared its neighborhood of most other orbiting bodies
A dwarf planet is defined as a celestial body that:
1. Orbits the sun
2. Is large enough to be rounded by its own gravity
3. Is not large enough to have cleared its neighborhood around its orbit
4. Is not a satellite
If an object is too small for it to be rounded by its own gravity, it is known as a small solar system body. With these evolving definitions, two bodies that were once recognized as planets were reclassified as dwarf planets.
In comparison
Earth
Our planet is the third from the sun. It is the largest terrestrial planet and the only one in the solar system with liquid water on the surface. Earths structure is composed of rock and metal. Oceans cover nearly 70% of the planets surface. Earth also has volcanoes, mountains and valleys.
Size: 7,918 miles in diameter
Distance from sun: 94.5 million miles
Length of year: 365 Earth days
Eris
Discovery: Oct. 21, 2003
Size: 1,444 miles in diameter
Distance from sun: 6.3 billion miles
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The History Of Dwarf Planets
A dwarf planet is a celestial body that almost meets the definition of a true planet. According to the IAU, which sets definitions for planetary science, a planet must:
Dwarf planets, along with not being moons or satellites, fail to clear the neighborhoods around their orbits. This is the primary reason why Pluto lost its status: because it shares part of its orbit with the Kuiper belt, a dense region of icy space bodies.
Based on this definition, the IAU has recognized five dwarf planets: Pluto, Eris, Makemake, Haumea, and Ceres. There are four more planetary objects*, namely Orcus, Sedna, Gonggong and Quaoar, that the majority of the scientific community recognize as dwarf planets.
Six more could be recognized in the coming years, and as many as 200 or more are hypothesized to exist in the Outer Solar System in the aforementioned Kuiper belt.
Ceres is the earliest known and smallest of the current category of dwarf planets. Previously classified as an asteroid in 1801, it was confirmed to be a dwarf planet in 2006. Ceres lies between Mars and Jupiter in the asteroid belt, and it is the only dwarf planet that orbits closest to Earth.
Here is a brief introduction to the most recognized dwarf planets:
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A New Class Of Objects And How To Define A Planet
The IAU has been responsible for the naming and nomenclature of planetary bodies and their satellites since the early 1900s. As Professor Ron Ekers, past president of the IAU, explains:
Such decisions and recommendations are not enforceable by any national or international law rather they establish conventions that are meant to help our understanding of astronomical objects and processes. Hence, IAU recommendations should rest on well-established scientific facts and have a broad consensus in the community concerned.The IAU decided to create a committee to gather opinions from a broad range of scientific interests, with input from professional astronomers, planetary scientists, historians, science publishers, writers and educators. Thus the Planet Definition Committee of the IAU Executive Committee was formed and quickly went about preparing a draft resolution to put to the members of the IAU. After the final meeting in Paris the draft resolution was completed. One crucial aspect of the resolution is described by Professor Owen Gingerich, Chair of the IAU Planet Definition Committee: “On the scientific side, we wanted to avoid arbitrary cut-offs simply based on distances, periods, magnitudes, or neighbouring objects”.
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