<p>See <a href="https://astronomy.stackexchange.com/questions/30246/could-a-planet-form-without-a-molten-state">Could a planet form without a molten state?</a>, where Anders Sandberg calculates that a body with radius ~ 1000 km would melt from the heat of formation. </p>

<p>The largest asteroid, <a href="https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)" rel="noreferrer">Ceres</a>, has a radius of 473 km, so it's a bit too small to have totally melted just from gravitational accretion, but it <em>may</em> have picked up a little more energy from impacts that were faster than freefall. It could also generate some internal heat from radioactive decay, but it's not expected to contain a significant percentage of radioactive material.</p>

<p>Presumably, Ceres was plastic to some degree during formation, since it's (almost) spherical (and it's the only asteroid large enough for gravity to make it spherical). But that wouldn't have required a very high temperature, since Ceres contains a lot of water ice.</p>

<p>But even if it did totally melt when it formed, it's had over 4 billion years to cool down, so it's extremely unlikely to still have a hot core. However, it does emit more water vapour than expected, and it may be warm enough to contain some liquid water below the surface.</p>

CC BY-SA 4.0
2019-04-08T06:53:25.897Z
2019-04-08T06:53:25.897Z
PM 2Ring
<p>'ll explain, the asteroids are small rocky objects that orbit the sun. Although asteroids orbit the sun like planets, they are much smaller than planets. Remember that most of them live in the asteroid belt that is that region between the orbits of Mars and Jupiter. Additionally some asteroids are in the orbital trajectory of the planets. This means that the asteroid and the planet follow the same path around the sun. You should also consider that these asteroids were usually all formed at the same time and that most of them are located at the furthest distances from the Kuipier belt that is closer to the 100UA. The fact is that due to their size and their physical characteristics, these objects can not have active nuclei.</p>

CC BY-SA 4.0
2019-04-08T18:22:55.397Z
You may want to expand your last sentence into an answer (why does their size not allow active nuclei?); the rest of the answer as written does not address the actual question.
Anders Sandberg
CC BY-SA 4.0
2019-04-12T14:19:29.823Z
there are no asteroids with active nuclei
jormansandoval
CC BY-SA 4.0
2019-04-08T00:11:06.023Z
2019-04-08T00:11:06.023Z
jormansandoval
<p>I was wondering if any of the asteroids we have ever seen has a hot core like Earth's.</p>

<p>I'm thinking that Earth has a strong gravitational field and so formation would have involved a lot of gravitational energy being converted to heat, but not so much for the asteroids.</p>

CC BY-SA 4.0
2019-04-07T23:58:01.130Z
Most asteroids will not have hot cores, the've long-since equilibrated. But I don't know about the biggest, and I guess those are suddenly no longer classified as asteroids, but as dwarf planets. I think a good answer would include them as well.
uhoh
<solar-system><asteroids><fundamental-astronomy><planetary-formation>
Does any asteroid we have ever seen have a hot core like earth.?
Srinivas
# Does any asteroid we have ever seen have a hot core like earth.?

(Asked by: username_0 on 2019-04-07)

I was wondering if any of the asteroids we have ever seen has a hot core like Earth's.

I'm thinking that Earth has a strong gravitational field and so formation would have involved a lot of gravitational energy being converted to heat, but not so much for the asteroids.

**Tags:** solar-system, asteroids, fundamental-astronomy, planetary-formation

> **Comments:**
> **username_1**: Most asteroids will not have hot cores, the've long-since equilibrated. But I don't know about the biggest, and I guess those are suddenly no longer classified as asteroids, but as dwarf planets. I think a good answer would include them as well.  

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## 2 answers

### Answer by username_2 on 2019-04-08. Score: 5

See [Could a planet form without a molten state?](https://astronomy.stackexchange.com/questions/30246/could-a-planet-form-without-a-molten-state), where username_4 username_4 calculates that a body with radius ~ 1000 km would melt from the heat of formation.

The largest asteroid, [Ceres](https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)), has a radius of 473 km, so it's a bit too small to have totally melted just from gravitational accretion, but it *may* have picked up a little more energy from impacts that were faster than freefall. It could also generate some internal heat from radioactive decay, but it's not expected to contain a significant percentage of radioactive material.

Presumably, Ceres was plastic to some degree during formation, since it's (almost) spherical (and it's the only asteroid large enough for gravity to make it spherical). But that wouldn't have required a very high temperature, since Ceres contains a lot of water ice.

But even if it did totally melt when it formed, it's had over 4 billion years to cool down, so it's extremely unlikely to still have a hot core. However, it does emit more water vapour than expected, and it may be warm enough to contain some liquid water below the surface.


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### Answer by username_3 on 2019-04-08. Score: -3

'll explain, the asteroids are small rocky objects that orbit the sun. Although asteroids orbit the sun like planets, they are much smaller than planets. Remember that most of them live in the asteroid belt that is that region between the orbits of Mars and Jupiter. Additionally some asteroids are in the orbital trajectory of the planets. This means that the asteroid and the planet follow the same path around the sun. You should also consider that these asteroids were usually all formed at the same time and that most of them are located at the furthest distances from the Kuipier belt that is closer to the 100UA. The fact is that due to their size and their physical characteristics, these objects can not have active nuclei.

> **Comments:**
> **username_4**: You may want to expand your last sentence into an answer (why does their size not allow active nuclei?); the rest of the answer as written does not address the actual question.  
> **username_3**: there are no asteroids with active nuclei  

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