<p>I'm inclined to say no (and footnote, I realize Wikipedia isn't a good source for scientific proof as it's not always right, but I'm using it more to demonstrate a point than than use it as an authoritative definition).     <a href="https://en.wikipedia.org/wiki/Terrestrial_planet" rel="nofollow">Wikipedia</a>:  </p>

<blockquote>
  <p>A terrestrial planet, telluric planet or rocky planet is a planet that
  is composed primarily of silicate rocks or metals.</p>
</blockquote>

<p>and</p>

<blockquote>
  <p>All terrestrial planets have approximately the same type of structure:
  a central metallic core, mostly iron, with a surrounding silicate
  mantle. The Moon is similar, but has a much smaller iron core. Io and
  Europa are also satellites that have internal structures similar to
  that of terrestrial planets.</p>
</blockquote>

<p>and</p>

<blockquote>
  <p>Dwarf planets, such as Ceres and Pluto, and large small Solar System
  bodies are similar to terrestrial planets in the fact that they do
  have a solid surface, but are, on average, composed of more icy
  materials (Ceres and Pluto have densities 2.17 and 1.87 g cm−3,
  respectively, and Haumea's density is similar to Pallas's 2.8 g cm−3).</p>
</blockquote>

<p>So, in my opinion, half ice/half rock if a different category and not terrestrial.   There probably are planets that formed outside the frost line that are half rock-half ice in other solar systems, but I don't think I'd call them terrestrial.   We probably need a new word for them.   </p>

<p>If Ceres was to drift closer to an Earth's orbit, it's ice would melt and it would have oceans (and an H20 rich atmosphere), at least, for a little while anyway until it lost it's atmosphere.   Planets with Ceres composition would likely be water worlds if they were warm enough.   </p>

<p>Now, I can't speak for any the official answer, but that's my opinion.  If Ceres is Terrestrial and Haumea is more rocky than Ceres, then Ceres probably shouldn't be the only terrestrial dwarf planet in the solar-system.  </p>

<ul>
<li>edit.</li>
</ul>

<p><a href="https://en.wikipedia.org/wiki/Geology_of_solar_terrestrial_planets" rel="nofollow">Link</a> provided that says Ceres is a terrestrial dwarf planet.</p>

<p>reasoning:</p>

<blockquote>
  <p>Terrestrial planets have numerous similarities to plutoids (objects
  like Pluto), which also have a solid surface, but are composed of more
  icy materials.</p>
</blockquote>

<p>Some of this is just semantics, but lets look at density, which is a pretty good measure of Water-Ice and other ices to Rock content.</p>

<p>Ceres 2.08 g/cm^3</p>

<p>and the other dwarfs, by size (not all of them are well measured so density isn't certain).</p>

<p>Eris 2.3
Pluto 1.88
Makemake ~2
Haumea  2.6-3.3
Quaoar ~2.2
Sedna (2.0?)</p>

<p>and I could go on.</p>

<p>Lets do a few moons, just for fun.</p>

<p>Io:  3.55  (extreme volcanism)
Europa:  3.0
Ganymede:  1.93
Calisto:  1.83
Titan:  1.88
Triton:  2.06
Enceladus:   1.61</p>

<p>Moons are easy, we don't call them dwarf planets even if they are larger than dwarf planets cause we call them moons. - definition averted.   :-)</p>

<p>But I have a hard time seeing why Ceres gets a different classification than other very similar objects which just happen to be further away.   Now, granted, Ceres, while it formed outside the frost line, it's now inside the frost line so surface ice on Ceres doesn't last.  It's got a rocky surface while most Kuiper belt objects have an icy surface.    I can see that, defining an object based on it's surface, but I still think a half rock/half ice object (of significant size, large enough to be round and meet dwarf planet criteria), should be called half rock-half ice or whatever that definition is.   I don't think it should be rocky/terrestrial if it's Ceres and icy if it's Pluto, even if that's how they look the surface, but that's just my opinion.  </p>

<p>/// hope that wasn't too much of a rant.  :-)</p>

CC BY-SA 3.0
2015-10-11T06:39:09.823Z
If you take Wikipedia as a source, this article https://en.wikipedia.org/wiki/Geology_of_solar_terrestrial_planets calls Ceres "terrestrial dwarf planet".
Anixx
CC BY-SA 3.0
2015-10-11T07:19:34.027Z
@Anixx well, it's hard to argue with a link that comes out and says it is (even if it's Wikipedia), but I still like my definition.   (will go into more in the question part, rather than here).
userLTK
CC BY-SA 3.0
2015-10-11T06:22:03.377Z
2015-10-11T19:53:21.137Z
2015-10-11T19:53:21.137Z
userLTK
<p>Does Ceres belong to the terrestrial-type celestial bodies?</p>

CC BY-SA 3.0
2015-10-11T03:31:38.183Z
According to the tag wiki, terrestrial planets have rocky surfaces. The surface of Ceres is more icy than rocky. On the other hand, that far from the sun water is effectively a mineral, and ice is a rock. Like a lot of questions about Solar System bodies, I think it's more a matter of what particular words mean than about the bodies themselves.
Keith Thompson
CC BY-SA 3.0
2015-10-11T03:43:19.290Z
@Keith Thompson "that far from the sun water is effectively a mineral, and ice is a rock" - actually Ceres is not that far (its surface temperature may reach -38C which is 50 degrees warmer than the coolest temperature registered on Earth). Moreover, surface ice is unstable at Ceres and sublimates, so only dust/rock can be directly exposed on the surface. Also Earth has most of its surface in form of liquid/icy water and not rock.
Anixx
CC BY-SA 3.0
2015-10-11T03:44:52.223Z
Good points. One quibble: It depends on what you mean by "surface". I might argue that most of the surface of Earth is rock that happens to be covered by water.
Keith Thompson
CC BY-SA 3.0
2015-10-11T03:47:09.650Z
@Keith Thompson if so, it is the case of any "ice body" because all of them have some rocks under the ice and rocky cores.
Anixx
CC BY-SA 3.0
2015-10-11T03:53:55.847Z
@Keith Thompson This site claims Ceres is a terrestrial-type world. But the authority of the site is doubtful. http://space-facts.com/terrestrial-planets/ "There is one dwarf planet considered to be terrestrial-type world: Ceres."
Anixx
CC BY-SA 3.0
2015-10-11T20:05:49.370Z
One possible method of categorization is icy surface vs rocky surface - Ceres is the only dwarf planet (large enough to be round), with a rocky surface, but if Pluto was to drift closer to the sun, it would lose it's icy surface and over time, have a rocky one too.   Should the definition of what an object is be defined by where it is?    I don't think so, personally, but I also see some shades of grey in my argument.   A moon, for example, is called a moon because of where it is and what it orbits.
userLTK
<dwarf-planets><terrestrial-planets><asteroid-belt><ceres>
Is Ceres a terrestrial-type (dwarf) planet?
Anixx
# Is Ceres a terrestrial-type (dwarf) planet?

(Asked by: username_0 on 2015-10-11)

Does Ceres belong to the terrestrial-type celestial bodies?

**Tags:** dwarf-planets, terrestrial-planets, asteroid-belt, ceres

> **Comments:**
> **username_1**: According to the tag wiki, terrestrial planets have rocky surfaces. The surface of Ceres is more icy than rocky. On the other hand, that far from the sun water is effectively a mineral, and ice is a rock. Like a lot of questions about Solar System bodies, I think it's more a matter of what particular words mean than about the bodies themselves.  
> **username_0**: @username_1 "that far from the sun water is effectively a mineral, and ice is a rock" - actually Ceres is not that far (its surface temperature may reach -38C which is 50 degrees warmer than the coolest temperature registered on Earth). Moreover, surface ice is unstable at Ceres and sublimates, so only dust/rock can be directly exposed on the surface. Also Earth has most of its surface in form of liquid/icy water and not rock.  
> **username_1**: Good points. One quibble: It depends on what you mean by "surface". I might argue that most of the surface of Earth is rock that happens to be covered by water.  
> **username_0**: @username_1 if so, it is the case of any "ice body" because all of them have some rocks under the ice and rocky cores.  
> **username_0**: @username_1 This site claims Ceres is a terrestrial-type world. But the authority of the site is doubtful. http://space-facts.com/terrestrial-planets/ "There is one dwarf planet considered to be terrestrial-type world: Ceres."  
> **username_2**: One possible method of categorization is icy surface vs rocky surface - Ceres is the only dwarf planet (large enough to be round), with a rocky surface, but if Pluto was to drift closer to the sun, it would lose it's icy surface and over time, have a rocky one too.   Should the definition of what an object is be defined by where it is?    I don't think so, personally, but I also see some shades of grey in my argument.   A moon, for example, is called a moon because of where it is and what it orbits.  

---

## 1 answers

### Answer by username_2 on 2015-10-11. Score: 2

I'm inclined to say no (and footnote, I realize Wikipedia isn't a good source for scientific proof as it's not always right, but I'm using it more to demonstrate a point than than use it as an authoritative definition). [Wikipedia](https://en.wikipedia.org/wiki/Terrestrial_planet):

> A terrestrial planet, telluric planet or rocky planet is a planet that
> is composed primarily of silicate rocks or metals.

and

> All terrestrial planets have approximately the same type of structure:
> a central metallic core, mostly iron, with a surrounding silicate
> mantle. The Moon is similar, but has a much smaller iron core. Io and
> Europa are also satellites that have internal structures similar to
> that of terrestrial planets.

and

> Dwarf planets, such as Ceres and Pluto, and large small Solar System
> bodies are similar to terrestrial planets in the fact that they do
> have a solid surface, but are, on average, composed of more icy
> materials (Ceres and Pluto have densities 2.17 and 1.87 g cm−3,
> respectively, and Haumea's density is similar to Pallas's 2.8 g cm−3).

So, in my opinion, half ice/half rock if a different category and not terrestrial. There probably are planets that formed outside the frost line that are half rock-half ice in other solar systems, but I don't think I'd call them terrestrial. We probably need a new word for them.

If Ceres was to drift closer to an Earth's orbit, it's ice would melt and it would have oceans (and an H20 rich atmosphere), at least, for a little while anyway until it lost it's atmosphere. Planets with Ceres composition would likely be water worlds if they were warm enough.

Now, I can't speak for any the official answer, but that's my opinion. If Ceres is Terrestrial and Haumea is more rocky than Ceres, then Ceres probably shouldn't be the only terrestrial dwarf planet in the solar-system.

* edit.

[Link](https://en.wikipedia.org/wiki/Geology_of_solar_terrestrial_planets) provided that says Ceres is a terrestrial dwarf planet.

reasoning:

> Terrestrial planets have numerous similarities to plutoids (objects
> like Pluto), which also have a solid surface, but are composed of more
> icy materials.

Some of this is just semantics, but lets look at density, which is a pretty good measure of Water-Ice and other ices to Rock content.

Ceres 2.08 g/cm^3

and the other dwarfs, by size (not all of them are well measured so density isn't certain).

Eris 2.3
Pluto 1.88
Makemake ~2
Haumea 2.6-3.3
Quaoar ~2.2
Sedna (2.0?)

and I could go on.

Lets do a few moons, just for fun.

Io: 3.55 (extreme volcanism)
Europa: 3.0
Ganymede: 1.93
Calisto: 1.83
Titan: 1.88
Triton: 2.06
Enceladus: 1.61

Moons are easy, we don't call them dwarf planets even if they are larger than dwarf planets cause we call them moons. - definition averted. :-)

But I have a hard time seeing why Ceres gets a different classification than other very similar objects which just happen to be further away. Now, granted, Ceres, while it formed outside the frost line, it's now inside the frost line so surface ice on Ceres doesn't last. It's got a rocky surface while most Kuiper belt objects have an icy surface. I can see that, defining an object based on it's surface, but I still think a half rock/half ice object (of significant size, large enough to be round and meet dwarf planet criteria), should be called half rock-half ice or whatever that definition is. I don't think it should be rocky/terrestrial if it's Ceres and icy if it's Pluto, even if that's how they look the surface, but that's just my opinion.

/// hope that wasn't too much of a rant. :-)

> **Comments:**
> **username_0**: If you take Wikipedia as a source, this article https://en.wikipedia.org/wiki/Geology_of_solar_terrestrial_planets calls Ceres "terrestrial dwarf planet".  
> **username_2**: @username_0 well, it's hard to argue with a link that comes out and says it is (even if it's Wikipedia), but I still like my definition.   (will go into more in the question part, rather than here).  

---

