<p>We can be pretty sure that the asteroid belt once held one or more sizable planetesimals,as there is evidence that it or they were large enough for gravity &amp; internal heating to drag the heavy metals (mainly iron &amp; nickel) to the centre,forming a metallic core. Bodes Law decrees that there should be a planet where the asteroid belt is now,but it seems that as this planet was forming it was shattered by an impact &amp; the remnants scattered. Some reached Earth,which is how we know that their materials had differentiated into metallic core &amp; rocky mantle. It is likely that some of the huge asteroids which have struck the Earth in the distant past were fragments thrown out of the asteroid belt &amp; that some hit Mars &amp; Venus as well. There may be more material in the asteroid belt than we think,because some fragments are so small &amp; widely dispersed that they don't register in our telescopes. I think we can assume that the primordial planetesimals had a similar though not identical composition to the asteroid belt of today.</p>

CC BY-SA 4.0
2019-05-30T20:41:57.000Z
2019-05-30T20:41:57.000Z
Michael Walsby
<p>According to one theory, the region between Mars and Jupiter was once populated by several primordial planets with a combined mass of roughly the earth.  These planets provided the material that made up the original asteroid belt.  Since then, 99.9% of this material was lost.  The current composition of the asteroid belt is about 10% metallic and 90% silicate/carbonaceous.  Could we assume that the original asteroid belt had the same composition?  Or, at least a very similar composition?  </p>

CC BY-SA 4.0
2019-05-27T18:09:15.160Z
Do you have a reference for that theory?  Or at least an epoch it was supposed to happen in? I guess it'd predate https://en.wikipedia.org/wiki/Grand_tack_hypothesis
PM 2Ring
CC BY-SA 4.0
2019-05-28T07:50:25.970Z
There was a planet there that exploded. That's the most plausible theory and it's supported by math (based on current planetary orbit distances).
Overmind
CC BY-SA 4.0
2019-05-29T01:28:54.980Z
@Overmind no, that’s a myth. Regarding the math, Bode’s Law was discredited long ago.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2019-05-29T09:43:48.873Z
If you consider Neptune to be the 'first' Kuiper belt object, then the law is correct. You must take SBOs into account, not only planets.
Overmind
<asteroid-belt>
What was the composition of the primordial asteroid belt?
Ninosław Brzostowiecki
# What was the composition of the primordial asteroid belt?

(Asked by: username_0 on 2019-05-27)

According to one theory, the region between Mars and Jupiter was once populated by several primordial planets with a combined mass of roughly the earth. These planets provided the material that made up the original asteroid belt. Since then, 99.9% of this material was lost. The current composition of the asteroid belt is about 10% metallic and 90% silicate/carbonaceous. Could we assume that the original asteroid belt had the same composition? Or, at least a very similar composition?

**Tags:** asteroid-belt

> **Comments:**
> **username_1**: Do you have a reference for that theory?  Or at least an epoch it was supposed to happen in? I guess it'd predate https://en.wikipedia.org/wiki/Grand_tack_hypothesis  
> **username_2**: There was a planet there that exploded. That's the most plausible theory and it's supported by math (based on current planetary orbit distances).  
> **username_3**: @username_2 no, that’s a myth. Regarding the math, Bode’s Law was discredited long ago.  
> **username_2**: If you consider Neptune to be the 'first' Kuiper belt object, then the law is correct. You must take SBOs into account, not only planets.  

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## 1 answers

### Answer by username_4 on 2019-05-30. Score: -2

We can be pretty sure that the asteroid belt once held one or more sizable planetesimals,as there is evidence that it or they were large enough for gravity & internal heating to drag the heavy metals (mainly iron & nickel) to the centre,forming a metallic core. Bodes Law decrees that there should be a planet where the asteroid belt is now,but it seems that as this planet was forming it was shattered by an impact & the remnants scattered. Some reached Earth,which is how we know that their materials had differentiated into metallic core & rocky mantle. It is likely that some of the huge asteroids which have struck the Earth in the distant past were fragments thrown out of the asteroid belt & that some hit Mars & Venus as well. There may be more material in the asteroid belt than we think,because some fragments are so small & widely dispersed that they don't register in our telescopes. I think we can assume that the primordial planetesimals had a similar though not identical composition to the asteroid belt of today.


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