Let me start with a very simple question. When is a planet not a planet?  Do you think this seems like a simple question?

Trust me, the answer is not as simple as you might think. Defining a planet into a particular category isn’t easy, with the debate continuing to rage as to how exactly planets should be classified.

What are dwarf planets?

According to International Astronomical Union (IAU),

Dwarf planets are spherical objects in the orbit around the sun that are not the moons, but they share their orbits with the other debris which they have not been able to clear.

In simple terms, a dwarf planet can be regarded as a spherical object in the solar system exhibiting all or some of the properties of the planet, but lacking the necessary gravitational strength to have pulled other local objects into its influence. 

A Planet must satisfy the below criteria according to the IAU:

  • A planet must be round.
  • It must orbit the sun.
  • It must have “cleared the neighbourhood” of its orbit. This means that as a planet travels, its gravity sweeps and clears the space around it of other objects. Some of the objects may crash into the planet, others may become moons.

Is Pluto a dwarf planet?

Yes, it is.

The reason is :

 Pluto follows the first two rules:  It is round, and it orbits the sun.

It does not, however, follow the third rule. It has not yet cleared the neighbourhood of its orbit in space. Because it does not follow this rule, Pluto is no longer considered a planet. (credits: Wondeopolis)

Not only, Pluto, there are some five planets that were recognized as dwarf planets in our solar system. 

They are:

  1. Pluto
  2. Eris
  3. Makemake
  4. Haumea
  5. Ceres

Apart from this, the dozen more resides in the Kuiper belt – a disc-shaped region beyond the Neptune was also considered as the candidates.

Few interesting facts about the Drawf planets in our solar system:

  • The Five official dwarfs and their unofficial brothers looks vary drastically in both the appearance and composition, just as the main eight planets of the solar system do.
  • Pluto is the one and the only dwarf planet to have its own moon. Its moon name is Charon.
  • Eris is the coldest known object in the solar system with its surface temperature reaching as low as -250 degrees Celsius.
  • Ceres – was once regarded as a large spherical asteroid but recently promoted. Ceres is the smallest known dwarf planet and the largest object in the asteroid belt between Mars and Jupiter.

Size of Dwarf Planets Vs Size of Earth:

The Below Image Shows how small the Dwarf planets will look when compared to our real planets in the solar system. The below comparison is made with respect to earth with 3 major Dwarf Planets in our solar system.

Dwarf planets as compared to earth
Dwarf planets as compared to earth



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