Dwarf Planets: Learn How They Are Formed With Examples

We know that Pluto is no longer a planet in our solar system. Pluto is now a dwarf planet. Why Pluto is categorised as a dwarf planet? And what exactly is meant by that? It is a celestial body which is almost spherical in shape and orbits a star but its size is lesser than an actual planet. It’s a bit confusing! So, in this Physics article, we will learn all about what dwarf planets are and other interesting facts regarding them.

Dwarf Planets

Dwarf planets are astronomical objects with nearly spherical shapes that orbit a star. As the name suggests, dwarf planets are smaller than planets. Dwarf planets lack the gravitational forces required to suck in and accumulate all of the material present in their orbits because they are smaller. A dwarf planet could be in for a bumpy ride as it travels – its path is full of other objects like asteroids. Every known dwarf planet in our solar system is smaller than our Moon.

There may be dozens of dwarf planets in our solar system. According to astronomers, the solar system and Kuiper Belt include up to 200 dwarf planets. So far, we’ve only classified a few. Most of them are quite far away. Pluto is the most well-known, but Ceres is a nearby world to us. Ceres is the first dwarf planet to have a spacecraft visit it. Ceres is the asteroid belt’s only dwarf planet. The rest of the dwarf planets are known as Plutoids and are found beyond Neptune in the Kuiper Belt.

How Are Dwarf Planets Formed?

The solar system was 4.6 billion years ago a cloud of dust and gas known as a solar nebula. As the material began to spin, gravity compressed it in on itself, generating the sun in the centre of the nebula.

The leftover material began to cluster up with the development of the sun. Small particles are gathered together, bound by gravity, to form larger particles. The solar wind swept away lighter components from the nearby areas, such as hydrogen and helium, leaving only heavy, stony ingredients to form smaller terrestrial worlds.

However, the solar winds had less of an impact on lighter components farther away, allowing them to form into gas giants. Asteroids, comets, planets, dwarf planets and moons were formed in this manner.

Under this scenario, Plutoid’s (dwarf planets that are farther from the Sun than Neptune) rocky core would have been the first to form. Gases and ices would have been drawn in gravitationally from there, with the core growing larger and larger. The dwarf planets did not gather enough mass to be classified as full-scale planets.

Also, learn about Life Cycle of a Star

Criteria of Dwarf Planets

Dwarf planets, like the eight major planets, are spherical in shape and orbit the Sun. Dwarf planets, unlike planets, cannot clear their orbital path. Hence, there are no similar objects at about the same distance from the Sun. A dwarf planet is significantly smaller than a planet (even smaller than Earth’s moon), but it is not a moon. Ceres, Pluto, Eris, Makemake, and Haumea were the first five confirmed dwarf planets, and they are all mysterious in their own way.

According to the International Astronomical Union, A dwarf planet follows the given criteria:

• It is a celestial entity that orbits the sun
• They have enough mass to assume a roughly spherical form
• They have not cleared the neighbourhood around their orbit and is not a moon

How was Pluto Named a Dwarf Planet?

Pluto, once assumed to be a planet, is now classified as a dwarf planet due to its mass and incapacity to sweep its surroundings clean. While the majority of the solar system’s objects orbit the sun on approximately the same plane, Pluto’s orbit takes it outside of the usual range.

Pluto is unusual in the solar system because it is a binary planet. The centre of mass for Pluto and its largest moon, Charon, is located outside of Pluto’s interior. This means that the ice duo may shed light not just on binary planets, but also on how planets develop in systems with two or more stars.

Pluto’s strange trajectory caused many scientists to believe that it had been kicked out of Neptune’s orbit at some point in its history. This was strengthened by the planet’s similarities to Neptune’s largest moon, Triton. However, Pluto’s orbit prevents it from colliding with the large planet, implying that it was never a part of its system.

After demonstrating that Pluto could not have been a part of Neptune’s system, astronomers began to look for another explanation for the then-strange planet’s behaviour. Their investigation took them to the Kuiper Belt, a cloud of rock and ice at the far reaches of the solar system.

Pluto stands out as a planet in terms of temperature, distance, and orbit, but as a Kuiper Belt Object, it is only one of the millions of rock and ice fragments. Although Pluto is the largest known object in the region, Eris is a close second and was initially assumed to be larger than Pluto. Pluto was reclassified as a dwarf planet rather than a full-scale planet in the solar system after the discovery of the massive dwarf planet, Eris in 2005.

Pluto was reclassified as a dwarf planet by the International Astronomical Union (IAU) on August 24, 2006. Pluto was thought to be a regular planet and the solar system’s outermost planet from 1930.

Some Dwarf Planets

Pluto
	Radius = 1,137 km
	Mass = 0.00213
	Orbital distance = 39.5 AU
	Location = Kuiper belt
	Year Length = 248.5 Earth Years
	Day Length = 6.39 Earth Days
	Surface Gravity = 0.04
	Surface Temperature = -230 °C
	Discovered = 1930
	Number of Moons = 3

Haumea
	Radius = 1,436 km
	Mass = 0.0007
	Orbital distance = 43.1 AU
	Location = Kuiper belt
	Year Length = 283.3 Earth Years
	Day Length = 0.16 Earth Days
	Surface Gravity = 0.044
	Surface Temperature = -240 °C
	Discovered = 2003
	Number of Moons = 2

Makemake
	Radius = 750 km
	Mass = 0.0007
	Orbital distance = 45.8 AU
	Location = Kuiper belt
	Year Length = 309.9 Earth Years
	Day Length = Unknown
	Surface Gravity = 0.05
	Surface Temperature = -243 °C
	Discovered = 2005
	Number of Moons = 0

Eris
	Radius = 1,300 km
	Mass = 0.003
	Orbital distance = 67.7 AU
	Location = Kuiper belt
	Year Length = 557 Earth Years
	Day Length = Unknown
	Surface Gravity = 0.08
	Surface Temperature = -240 °C
	Discovered = 2003
	Number of Moons = 1

 

Ceres
	Radius = 487 km
	Mass = 0.00016
	Orbital distance = 2.77 AU
	Location = Asteroid belt
	Year Length = 4.6 Earth Years
	Day Length = 0.38 Earth Days
	Surface Gravity = 0.003
	Surface Temperature = -105 °C
	Discovered = 1801
	Number of Moons = 0

* = Earth Mass =

* = Earth Gravity =

Difference Between Dwarf Planet and Planet

Some main differences between a dwarf planet and a planet is given below.

Dwarf Planet	Planet
A dwarf planet is likewise a spherical entity orbiting the sun. It must be smaller than 3031 miles in diameter and heavy enough to resemble a planet.	A planet is a spherical rocky or gaseous celestial body that orbits the sun but does not emit its own light.
A dwarf planet does not have definitive gravity of its own.	A planet is a celestial body with sufficient mass to have its own gravity.
A dwarf planet is too small to have a defined orbital path, and it does not orbit another object, such as a moon.	A planet has a clear circular/elliptical path around its star.
“dwarf planet” is a celestial body that has not cleared the neighbourhood around .ts orbit	A planet is a celestial body that has cleared the neighbourhood around its orbit.

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