Dwarf Planet

Dwarf Planet Meaning

So, what is a dwarf planet? As we all know that our universe seems infinitely large. Even trying to comprehend its size is profound in itself. Space is filled with a ton of fascinating objects known as heavenly bodies or celestial bodies. There are several types of heavenly bodies such as planets, stars, moons, asteroids, meteors, dwarf planets and many more. We are very tiny as compared to these objects. Some of the planets are way larger than our planet earth. We are on a continuous quest to discover these bodies based on our current technological capabilities. There are more than a billion stars in our milky way galaxy, and more than fifty such galaxies combine to form a local group. It is always fascinating to learn about these objects. 

Due to the sheer size of these bodies, we have not even discovered a tiny fraction of our galaxy. There are several mnemonics available to remember the names of the planets in our solar system and you can also make your own as per your comfort. Today we will focus on dwarf planets and find out What is a dwarf planet? Our solar system also contains a dwarf planet named Pluto. We used to count it as one of the planets, but due to some complications now it falls under the category of dwarf planets. Below we will learn about Dwarf planets, dwarf planet meaning, and look at a dwarf planets list.


What is a Dwarf Planet?

So let us start by understanding the dwarf planet definition. Dwarf planets are celestial bodies or planetary-mass objects(having a mass equivalent to a planet) that are not satellites and also do not dominate their region, unlike the regular planets. These bodies are too large to be categorized in the smaller objects and too large to be called a full-fledged planet. According to the international astronomical unit, a planet needs to meet specific criteria to be called the dwarf planet. First, it should directly orbit around the sun like other planets. Second, it needs to have enough gravity so that it can pull its mass in a spherical or round shape. Lastly, its orbit needs to be clear of small objects. 

The above criteria describe the dwarf planet’s meaning, and if a planet meets all these criteria, then it is categorized as a dwarf planet. However, the critical difference between planets and dwarf planets is in that last criteria. A regular planet has a substantial amount of mass or gravity to pull or push away the objects that obstruct its orbital path. In the case of dwarf planets, their gravity or mass is not adequate to perform this maneuver. It is challenging to pinpoint the total number of dwarf planets in the solar system(milky way). To classify or approve a celestial body as a dwarf planet, we need to observe it closely.

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( Dwarf Planets )

Alan Stern was the first person to introduce dwarf planets in his three-part categorization of planetary objects(having the mass equivalent to planets) in our solar system. He called them satellite planets, classical planets, and dwarf planets.  Ultimately the international astronomical union accepted the term dwarf planet in 2006. There are several known or discovered dwarf planets such as Pluto, Eris, Ceres, Haumea, and Makemake. The scientific society believes that there are still more than a hundred dwarf planets that need to be discovered. So, you must be wondering which planet is known as Dwarf planet? Let us move on to a dwarf planets list and categorize which is the dwarf planet?. 


Which is the Dwarf Planet?

Based on the dwarf planet meaning we will look at planets and determine which is the dwarf planet? Below is the discovered dwarf planets list and their discovery dates respectively.

  • Pluto:- It was previously in the category of planets, but since 2006 it is considered a dwarf planet.

  • Ceres:- This celestial body was also considered a planet until 2006. It was discovered in 1801. 

  • Eres:- it was discovered in 2005.

  • Makemake:- We classified it as a dwarf planet in 2008.

  • Haumea:- discovered in 2004, announced in 2005 and classified as a dwarf planet in 2008.


How was Pluto Named a Dwarf Planet?

You must remember the mnemonic My Very Educated Mother Just Served Us Nine Pizzas for all the planets in the solar system. The last one pizzas use to represent pluto as it was considered as one of the nine planets in our solar system. It was discovered on February 18, 1930, and since then it was considered as a planet. But since 2006 the international astronomical union reclassified it as a dwarf planet. It used to come very close to the sun in its orbital path and considered an odd planet. An astronomer named Michael brown discovered a similar-sized object as pluto called Eris. Later, when the terminology dwarf planet came to being then both of these objects were reclassified into this category.   

FAQ (Frequently Asked Questions)

1. Do Asteroids Fall Under the Category of Dwarf Planets?

No, asteroids do not fall under the category of dwarf planets. These heavenly bodies have a rocky structure and are mainly found in the asteroid belts of planets such as Mars and Jupiter. According to the properties of dwarf planets, these objects are not capable of moving in a spherical path and hence are not classified as dwarf planets.

2. What Are Planetary-Mass Moons?

Moons are the natural satellites revolving around planets. Some moons are in equilibrium shape due to relaxing on their gravity. However, some of them are not in equilibrium due to their frozen solid structure. Seven such moons are way bigger than pluto but not different from the dwarf planets. But these moons are not compatible with the international astronomical union’s definition and hence are considered as planetary-mass moons. In simple terms, the planetary-mass moon has the mass equivalent to a planet and does not meet the criteria of a dwarf planet.