What are dwarf planets, and how many are there?
In 2006, Pluto was famous downside From a planet to a dwarf planet. There remains the most famous dwarf planet today, but there are others in our solar system, including potentially discovered hundreds.
But what is it exactly a dwarf planet? And how many dwarf planets are there?
A dwarf planet is a celestial body which is smaller than a planet but larger than an asteroid or another small rock in the solar system. They are not planets because they only meet two of the three criteria for something in space to be considered a real planet.
A planet is Defined by three qualities: It orbit the sun, it is especially round, and it is massive enough for its severity to mainly give a kick of large objects of its orbit. Pluto and some other known dwarf planets meet the first two criteria but not the third because they orbit the Kuiper belt, a region beyond Neptune filled with small frozen debris.
When Pluto was discovered for the first time in 1930, he (and other similar objects in the Kuiper belt) were so distant and weak that they were really difficult to spot, even with the most powerful telescopes at the time. Indeed, the very qualities that make something a dwarf planet make these objects particularly difficult to detect.
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“There are a few things that are right for us to spot them”, ” Mathew yuA UCLA astronomer, told Live Science in an email. “They are far from the sun. The light reflected from their part is weak.
In addition, “they move slowly in the sky because of their great distance from the sun,” he added. “They go around the sun once every hundreds of years of earth. So their movements relating to the background stars are small. For astronomers with a limited observation time, these objects become difficult to detect.”
Astronomers have improved a lot to find objects in the Kuiper belt in the 1990s and 2000s as telescope technology improved. And once they could see a little better, they noticed that there were many more rocks with orbits similar to those of Pluto. Between 2002 and 2005, astronomers found seven more particularly large rocks: Haumea,, Makemake,, Quaoar,, Sedna,, Orcus,, Erris And Salacia.
THE International Astronomical Union (IAU) – The group of astronomers who decides on official names and terms for things in space – decided in 2006 That a new category was necessary to describe these objects which were large enough but not large enough to erase their orbits as a real planet does. Thus, the name “Dwarf Planet” was born.
How many dwarf planets are there?
With eight large rocks named in the Kuiper belt, you might think that it means that there are eight dwarf planets. However, not all astronomers agree on the number.
“The accepted figures vary between around 10 and a few hundred in the Kuiper belt alone,” said Yu. “Some people believe that there can be up to tens of thousands beyond the Kuiper belt.”
IAU has officially recognized only five dwarf planets: Pluto, Haumea, Makemake and Eris in the Kuiper belt, more Ceron in the asteroid belt. We sent space probes to only two of them: Pluto (visited by The new horizons of NASA) and ceres (visited by NASA Dawn), both stolen by these organizations in 2015.
Astronomers who observe dwarf planets, however, tend to recognize nine: the previous five, more Quaoar, Sedna, Orcus and Gonggong. GongGong was discovered in 2007 after changing the name of the dwarf planet, but it was only confirmed by Some new observations of NASA telescopes in 2016. IAU still plans proposals on these dwarf bodies.
There are at least one handful of additional objects that have been proposed but need more observations to confirm their size and, therefore, the status of dwarf planet.
And in June 2025, scientists proposed A new dwarf planet possible: 2017 of 201. Astronomers have found this object particularly low by seeking an old pile of data with new advanced algorithms.
If you count all the dwarf planets currently offered more the newcomer, that is eighteen dwarf planets or more in the solar system – and these are only those we have seen. There are probably more, perhaps even hundreds or thousands, one day being revealed while our telescopes continue to improve.
