Dwarf Planets

What are Dwarf Planets?

Dwarf Planets are smaller versions of the solar system’s eight planets. Like planets. they are large objects that orbits around the Sun. The Category “Dwarf Planet” was created as a result of extreme debate as to whether Pluto should be called a planet. Pluto had been considered solar system’s ninth planet for almost 50 years. However, in 2006, IAU defined  ‘planet’ in a manner that only eight bodies in the solar system qualified to be classified under the category. Therefore new class of “Dwarf Planets ” was established.

Dwarf Planets

Dwarf Planet - Ceres

Ceres is currently the smallest classified dwarf planet yet it is the largest object in the asteroid belt, which lies between Mars and Jupiter’s orbits. It’s made of rock and ice. It has a diameter of about 940 km and contains one-third of the mass of the asteroid belt.

Ceres Dwarf Planet

What is Ceres made up of?

The thin, dusty crust is thought to be rock, with a rocky inner core at its centre. Ceres’ surface, according to observations from Earth, contains iron-rich clays. Carbonates have also been discovered. Ceres is one of only two bodies in the solar system known to contain these minerals, the other two being Earth and Mars. Carbonates may be useful in predicting habitability.

Ceres' characteristics

Ceres has a density of 2.09 g/cm, implying that it is roughly one-quarter water, according to scientists. This would provide the dwarf planet with more fresh water than Earth does. Due to the extremely low temperatures, water on Ceres’ surface would convert, potentially creating a thin atmosphere.

History and Exploration

Giuseppe Piazzi, a Sicilian astronomer, discovered what was thought to be a planet and named it Ceres after the Roman goddess of corn and harvests. Within a decade, four new objects, all of which were classified as planets, were discovered in the same region. Ceres was demoted to the status of asteroid nearly 50 years ago. In 2006, it was designated as a dwarf planet. It did not achieve full planetary status because its orbit was not gravitationally cleared of debris.

Dwarf Planet - Haumea

Haumea is the third dwarf planet from the Sun. It has the least spherical shape of all dwarf planets due to its unusual elongated shape. It is one of our solar system’s fastest rotating objects. It rotates on its axis, every 3.92 hours. The dwarf planet’s rapid spinning has elongated it into an unusual shape discovered by astronomers in 2003. It is almost as big as Pluto. Haumea, like Pluto and Eris, orbits our Sun in the Kuiper belt. It was discovered in March 2003 at Spain’s Sierra Nevada Observatory. Its discovery was officially announced in 2005, the same year that its moons were discovered.

Haumea Dwarf Planet


Haumea is a “plutoid,” or dwarf planet, located beyond Neptune’s orbit. It was previously classified as a Kuiper belt object before being reclassified as the solar system’s fifth dwarf planet, following Ceres, Pluto, Eris, and Makemake. To honor the Hawaiian goddess of fertility and childbirth, the plutoid’s name was changed. The goddess’s two daughters, Hi’iaka and Namaka, were named after the moon’s two moons.


Haumea is roughly one-third the size of Pluto. It is the fastest known large spinning object in the solar system. Haumea’s orbit around the Sun lasts 285.46 Earth years. It is only 34 times the distance between the Earth and the Sun at its closest point, but it is more than 51 times the distance at its farthest point.


Because different materials stretch out differently, the dwarf planet’s rapid spin allowed researchers to determine its density. As a result, scientists believe it is predominantly composed of rock. Planetary observations, on the other hand, reveal a brilliantly gleaming surface. The researchers proposed a hypothesis. The interior of the dwarf planet is rough, but it is protected by a thin icy shell.

Haumean moons

The two moons of Haumea are much smaller than the dwarf planet. Hi’iaka, the largest, accounts for only about 0.5 percent of Haumea, while Namaka, the smallest and faintest, accounts for only about 0.05 percent of Haumea. On January 26, 2005, a group of space experts led by Mike Brown of the California Institute of Technology discovered Hi’iaka. Namaka was discovered by the same group on June 30, 2005.

Dwarf Planet Comparison

Dwarf Planet - Makemake

The fourth body in the outer solar system to be identified as a dwarf planet is Makemake. It was discovered around the same time when Eris was a considered to be named as the 10th planet of the solar system. It was during this period that the IAU gave a clear definition of a planet. As a result, Makemake and Eris were classified as dwarf planets. Since Eris is bigger than Pluto, Pluto was downgraded to a dwarf planet.

Dwarf Planet Makemake 1

The Easter bunny

Makemake was first observed in March 2005 by a team of astronomers at the Palomar Observatory. Officially known as 2005 FY9, the tiny planetoid was nicknamed “Easter bunny” by the group. It is named after the god of fertility in Rapa Nui mythology. The Rapa Nui inhabit Easter Island in the south eastern Pacific Ocean. Their chief god is Makemake who is also the creator of humanity and the god of fertility.


The dwarf planet is reddish brown in colour, leading scientists to conclude that it contains a layer of methane on its surface. There are also signs of frozen ethane and frozen nitrogen.


Unlike Pluto and Haumea, Makemake has no moon. This makes it difficult to find out its mass and density. Astronomers made use of its passage in front of a star to determine that it does not have a significant atmosphere. This is unusual since it is similar to Pluto which does have a thin one.


Makemake is one of the largest known objects in the outer solar system, just slightly smaller and dimmer than Pluto. Scientists think that it is about two-thirds the size of Pluto. It orbits beyond the range of Pluto, taking approximately 306 Earth-years to revolve around the Sun.

Dwarf Planet - Eris

Eris is a trans-Neptunian dwarf planet, or plutoid. The plutoid is named after Eris, the Greek goddess of discord and strife who instilled jealousy and envy in the other goddesses, resulting in the Trojan War. It is classified as a scattered-disc object based on its orbital characteristics (SDO). It is thought to have “scattered from the Kuiper belt into more distant and unusual orbits as a result of gravitational interactions with Neptune during the solar system’s formation.” Specifications

Eris Dwarf Planet

Eris' Moon

Eris received its official name from the IAU at the same time as its moon  Dysnomia. It is named after Eris, the Greek goddess of lawlessness, and her daughter. Dysnomia is a small moon that orbits its dwarf planet every two weeks. It is roughly eight times the size of Eris. Astronomers are currently investigating the connection between Dysnomia and Eris. They will be able to estimate the mass of the dwarf planet and its moon if they have a better understanding of how they interact.

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