<p>There are no discovered TNOs that would be as large as Eris (which is a little bit smaller than Pluto) or larger, but recent observation lead to a new estimate of <a href="https://en.wikipedia.org/wiki/Haumea" rel="nofollow noreferrer">Haumea's</a> equatorial diameter that could be 2322 km (1443 mi) and thus about as large as that of Eris. However, Haumea has an extremely weird shape, it is very flattened on the poles and its equatorial diameter is in one axe shorter and in the other axe longer (the diameter I mentioned). Haumea's mass is a third of Pluto's.</p>
<p>Other than those three bodies Pluto, Eris and Haumea, it is unlikely they will discover anything at their sizes or larger beyond Neptune, except for the hypothetical planet IX whose existence is assumed from the orbits of scattered disc objects. The planet would either be a super-Earth or a mini-Neptune or it might also be a primordial black hole.</p>
<p>So the claims that there would be so many Pluto-sized objects in the Kuiper belt are just plain wrong.</p>

CC BY-SA 4.0
2020-11-14T21:13:46.123Z
Do you have a source for it being "unlikely they will discover....."?
Steve Linton
CC BY-SA 4.0
2020-11-15T07:45:10.437Z
@SteveLinton They already discovered all objects the size of Eris or larger whose orbits are entirely in the Kuiper belt (and Eris isn't, it just crosses it but its aphelion is outside the belt) so any undiscovered Pluto-sized KBO would have to either be very dark for some reason, or would just be a Kuiper belt crosser/close-comer like Eris or Sedna.
John
CC BY-SA 4.0
2020-11-14T09:39:37.867Z
2020-11-14T09:39:37.867Z
John
<p>An object approximately the same size as Pluto, Eris, was discovered only 8 years ago (in 2005). Are there any Pluto-sized objects remaining to be discovered, and if so, how far away from the Sun would they have to be to not have been detected already?</p>

CC BY-SA 4.0
2020-11-14T20:50:37.313Z
[So far, more than 2,000 Kuiper Belt objects, or KBOs, have been cataloged by observers, but they represent only a tiny fraction of the total number of objects scientists think are out there. Astronomers estimate there are hundreds of thousands of objects in the Kuiper Belt region that are at least 60 miles- (100 kilometers-) wide or larger.](https://solarsystem.nasa.gov/news/792/10-things-to-know-about-the-kuiper-belt/) NASA does not give a reference where we might find estimates of the number of larger objects.
Keith McClary
CC BY-SA 3.0
2013-10-01T20:18:58.443Z
@UV-D: That's my understanding as well. We can be confident that there are no undiscovered Pluto-sized objects in the inner Solar System; if they existed, we certainly would have seen them by now. The question is, what is the corresponding level of confidence for such objects in the Kuiper Belt?
Keith Thompson
<solar-system><kuiper-belt>
Are any Pluto-sized objects remaining to be discovered in the Kuiper Belt?
Guillochon
# Are any Pluto-sized objects remaining to be discovered in the Kuiper Belt?

(Asked by: username_0 on 2013-10-01)

An object approximately the same size as Pluto, Eris, was discovered only 8 years ago (in 2005). Are there any Pluto-sized objects remaining to be discovered, and if so, how far away from the Sun would they have to be to not have been detected already?

**Tags:** solar-system, kuiper-belt

> **Comments:**
> **username_2**: @UV-D: That's my understanding as well. We can be confident that there are no undiscovered Pluto-sized objects in the inner Solar System; if they existed, we certainly would have seen them by now. The question is, what is the corresponding level of confidence for such objects in the Kuiper Belt?  
> **username_1**: [So far, more than 2,000 Kuiper Belt objects, or KBOs, have been cataloged by observers, but they represent only a tiny fraction of the total number of objects scientists think are out there. Astronomers estimate there are hundreds of thousands of objects in the Kuiper Belt region that are at least 60 miles- (100 kilometers-) wide or larger.](https://solarsystem.nasa.gov/news/792/10-things-to-know-about-the-kuiper-belt/) NASA does not give a reference where we might find estimates of the number of larger objects.  

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## 1 answers

### Answer by username_3 on 2020-11-14. Score: 1

There are no discovered TNOs that would be as large as Eris (which is a little bit smaller than Pluto) or larger, but recent observation lead to a new estimate of [Haumea's](https://en.wikipedia.org/wiki/Haumea) equatorial diameter that could be 2322 km (1443 mi) and thus about as large as that of Eris. However, Haumea has an extremely weird shape, it is very flattened on the poles and its equatorial diameter is in one axe shorter and in the other axe longer (the diameter I mentioned). Haumea's mass is a third of Pluto's.

Other than those three bodies Pluto, Eris and Haumea, it is unlikely they will discover anything at their sizes or larger beyond Neptune, except for the hypothetical planet IX whose existence is assumed from the orbits of scattered disc objects. The planet would either be a super-Earth or a mini-Neptune or it might also be a primordial black hole.

So the claims that there would be so many Pluto-sized objects in the Kuiper belt are just plain wrong.

> **Comments:**
> **username_4**: Do you have a source for it being "unlikely they will discover....."?  
> **username_3**: @SteveLinton They already discovered all objects the size of Eris or larger whose orbits are entirely in the Kuiper belt (and Eris isn't, it just crosses it but its aphelion is outside the belt) so any undiscovered Pluto-sized KBO would have to either be very dark for some reason, or would just be a Kuiper belt crosser/close-comer like Eris or Sedna.  

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