<p>There's a principal in science that a strong hypothesis doesn't depend on numerous improbable factors.  I read that somewhere, I think it was Phil Plait who created the bad astronomy website, but I can't find it right now.</p>

<p>For Mercury to have done what you claim, a 2nd planet would have needed to form between Earth and Jupiter, OK, maybe that happened, in fact, the young solar system was probably full of protoplanets.</p>

<p>This planet would then have needed to change it's orbit.  This usually takes a more massive planet to toss the smaller one, but there's two problems here.  Could Mars push Mercury all the way into Earth's orbit?    Probably not.   Could Jupiter?   Sure, but then, where did Mercury get all it's Iron if it formed between Mars and Jupiter.  It's becoming problematic. </p>

<p>Planet on planet collisions are rare, obviously not impossible.</p>

<p>Then there's the problem of how did the collison result in Mercury flying off, losing some material, the moon forming and Earth rapidly rotating.  Planet on planet collisions tend not to be glancing blows because planets are too big, and gravitational wells are pretty deep.   I don't want to say it's impossible but that's an odd scenario which seems highly unlikely.</p>

<p>And then, Mercury changes it's orbit again, perhaps gravitational assist from Venus and it ends up where it is.</p>

<p>A hypothesis like that depends on that many rare events all happening isn't not going to be a popular one.   Building a hypothesis on a single improbable event is fine.   The giant impact theory began like that.</p>

<p>A good hypothesis also has evidence behind it.   Mercury looks like it formed about where it is now, clearing out it's orbital neighborhood and being made up of denser material that was more likely to orbit closer to the sun.    There's very little reason to stand behind the Mercury impacted Earth idea and there's no evidence to support it.</p>

CC BY-SA 4.0
2019-07-27T22:25:29.757Z
Thank you for your answer. I thought it was an interesting question and put it here as the answers are most often well thought out.
Kevin Burke
CC BY-SA 4.0
2019-07-26T20:55:35.047Z
2019-07-26T20:55:35.047Z
userLTK
<p>It is highly improbable that the moon was created by a collision between Earth and Mercury, or that there has ever been such a collision. The idea that Mercury was formed in what sounds from your description like the asteroid belt and from there migrated to its present orbit, striking the Earth on the way, is pure speculation and there is no evidence for it. Nobody has ever taken the idea seriously enough to spend a lot of time and effort and possibly money looking into it. And if Mercury can go blundering about the solar system, bumping into obstacles on its way, how do we know that Mars won't do the same thing one day?.</p>

CC BY-SA 4.0
2019-07-26T18:15:39.497Z
2019-07-26T18:15:39.497Z
Michael Walsby
<p>I believe the documentry the 1st person was referring is called, Mercury: The Scorched Planet.  It is listed on YouTube by the BBC Earth Lab.  It explains the findings from the recent probe that spent 4 years orbiting Mercury.  The scientists state that Mercury had to have formed further out in the Solar System because it has far too many volatile minerals on its surface.  If Mercury formed where it is now, those minerals would have burned off.  Also, Mercury is mostly a core with a very thin crust. Therefore the scientists proposed that Mercury was a larger planet, perhaps Mars size, and it had a glancing blow with another planet.  This blow stripped off a lot of its outer crust, and sent Mercury into the inner Solar System where it came to settle in its current orbit.</p>
<p>Knowing the Great Impact theory for the creation of the Moon, I could not help thinking the impact, these scientist claimed Mercury had, sounded a lot like the Moon's creation.  This theory says a Mars size planet forming in the early Solar Sytem, struck the Earth (the computer simulations look glancing like) causing the Earth to spin faster and the debris to coalesce into the Moon.</p>
<p>To me, these two theories seem to be like 2 halves of a coin.  We just need to bring them together.  I did some simple math.  The size of the Moon, adding to the size of Mercury comes out to be just a little under the size of Mars.  Instead of two different glancing impacts around/near Eath's orbit, perhaps it was only one.  It created the Eath's Moon, and sent, the now smaller Mercury, into the inner Solar System.  I know a lot more research is needed, but perhaps this is a start.</p>

CC BY-SA 4.0
2021-12-18T07:06:35.873Z
The Great Impact hypothesis is the current favourite theory for the Moon's creation, but there's certainly room for alternate hypotheses. It would be great if we had actual samples of Mercury crust to analyse. It would also be good to do orbit simulations, to see how plausible some kind of Mercury collision scenario is. It  does appear that Mercury has experienced a rather extreme impact: there are what look like fracture lines that converge at the antipodes of the [Caloris](https://en.wikipedia.org/wiki/Caloris_Planitia) impact basin.
PM 2Ring
CC BY-SA 4.0
2021-12-18T16:34:17.747Z
This does not provide an answer to the question. Once you have sufficient [reputation](https://astronomy.stackexchange.com/help/whats-reputation) you will be able to [comment on any post](https://astronomy.stackexchange.com/help/privileges/comment); instead, [provide answers that don't require clarification from the asker](https://meta.stackexchange.com/questions/214173/why-do-i-need-50-reputation-to-comment-what-can-i-do-instead). - [From Review](/review/late-answers/28465)
WarpPrime
CC BY-SA 4.0
2021-12-18T06:17:12.237Z
2021-12-18T06:17:12.237Z
History Buff
<p>Earth's Moon is thought to have been created in a glancing collision with a Mars sized planet.</p>

<p>I've just seen an expose on Mercury which claimed Mercury: formed in the region between Earth and Jupiter, migrated to it's current orbit through an unknown interaction,  consist of 60% core material which was explained as the result of a glancing blow with a planet sized object.</p>

<p>Has anyone looked in to whether a Mercury/Earth collision could be the creator of our Moon?</p>

CC BY-SA 4.0
2019-07-26T19:13:01.550Z
That Mars-sized planet destroyed. Mercury now exists. Maybe if the collision created three major bodies (Earth, Moon and Mercury), and Mercury has somehow got a trajectory what slowly shifted it into its current orbit... I would not say that it is impossible, but extreme unlikely. [Here](http://parkersolarprobe.jhuapl.edu/The-Mission/images/16-00815_MissionDesign.png) is the orbit of the Parker Solar Probe, it uses the Venus to get near to the Sun, imagine the probability of this to happen randomly.
peterh
CC BY-SA 4.0
2021-12-18T06:55:17.020Z
Related: https://www.scientificamerican.com/article/does-mercury-hold-clues-to-birth-of-earth-moon/
PM 2Ring
<the-moon>
Could Mercury be the creator of Earth's Moon?
Kevin Burke
# Could Mercury be the creator of Earth's Moon?

(Asked by: username_0 on 2019-07-26)

Earth's Moon is thought to have been created in a glancing collision with a Mars sized planet.

I've just seen an expose on Mercury which claimed Mercury: formed in the region between Earth and Jupiter, migrated to it's current orbit through an unknown interaction, consist of 60% core material which was explained as the result of a glancing blow with a planet sized object.

Has anyone looked in to whether a Mercury/Earth collision could be the creator of our Moon?

**Tags:** the-moon
> **Comments:**
> **username_1**: That Mars-sized planet destroyed. Mercury now exists. Maybe if the collision created three major bodies (Earth, Moon and Mercury), and Mercury has somehow got a trajectory what slowly shifted it into its current orbit... I would not say that it is impossible, but extreme unlikely. [Here](http://parkersolarprobe.jhuapl.edu/The-Mission/images/16-00815_MissionDesign.png) is the orbit of the Parker Solar Probe, it uses the Venus to get near to the Sun, imagine the probability of this to happen randomly.  
> **username_2**: Related: https://www.scientificamerican.com/article/does-mercury-hold-clues-to-birth-of-earth-moon/  

---

## 3 answers

### Answer by username_3 on 2019-07-26. Score: 4

There's a principal in science that a strong hypothesis doesn't depend on numerous improbable factors. I read that somewhere, I think it was Phil Plait who created the bad astronomy website, but I can't find it right now.

For Mercury to have done what you claim, a 2nd planet would have needed to form between Earth and Jupiter, OK, maybe that happened, in fact, the young solar system was probably full of protoplanets.

This planet would then have needed to change it's orbit. This usually takes a more massive planet to toss the smaller one, but there's two problems here. Could Mars push Mercury all the way into Earth's orbit? Probably not. Could Jupiter? Sure, but then, where did Mercury get all it's Iron if it formed between Mars and Jupiter. It's becoming problematic.

Planet on planet collisions are rare, obviously not impossible.

Then there's the problem of how did the collison result in Mercury flying off, losing some material, the moon forming and Earth rapidly rotating. Planet on planet collisions tend not to be glancing blows because planets are too big, and gravitational wells are pretty deep. I don't want to say it's impossible but that's an odd scenario which seems highly unlikely.

And then, Mercury changes it's orbit again, perhaps gravitational assist from Venus and it ends up where it is.

A hypothesis like that depends on that many rare events all happening isn't not going to be a popular one. Building a hypothesis on a single improbable event is fine. The giant impact theory began like that.

A good hypothesis also has evidence behind it. Mercury looks like it formed about where it is now, clearing out it's orbital neighborhood and being made up of denser material that was more likely to orbit closer to the sun. There's very little reason to stand behind the Mercury impacted Earth idea and there's no evidence to support it.

> **Comments:**
> **username_0**: Thank you for your answer. I thought it was an interesting question and put it here as the answers are most often well thought out.  

---

### Answer by username_4 on 2019-07-26. Score: 0

It is highly improbable that the moon was created by a collision between Earth and Mercury, or that there has ever been such a collision. The idea that Mercury was formed in what sounds from your description like the asteroid belt and from there migrated to its present orbit, striking the Earth on the way, is pure speculation and there is no evidence for it. Nobody has ever taken the idea seriously enough to spend a lot of time and effort and possibly money looking into it. And if Mercury can go blundering about the solar system, bumping into obstacles on its way, how do we know that Mars won't do the same thing one day?.


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### Answer by username_5 on 2021-12-18. Score: -1

I believe the documentry the 1st person was referring is called, Mercury: The Scorched Planet. It is listed on YouTube by the BBC Earth Lab. It explains the findings from the recent probe that spent 4 years orbiting Mercury. The scientists state that Mercury had to have formed further out in the Solar System because it has far too many volatile minerals on its surface. If Mercury formed where it is now, those minerals would have burned off. Also, Mercury is mostly a core with a very thin crust. Therefore the scientists proposed that Mercury was a larger planet, perhaps Mars size, and it had a glancing blow with another planet. This blow stripped off a lot of its outer crust, and sent Mercury into the inner Solar System where it came to settle in its current orbit.

Knowing the Great Impact theory for the creation of the Moon, I could not help thinking the impact, these scientist claimed Mercury had, sounded a lot like the Moon's creation. This theory says a Mars size planet forming in the early Solar Sytem, struck the Earth (the computer simulations look glancing like) causing the Earth to spin faster and the debris to coalesce into the Moon.

To me, these two theories seem to be like 2 halves of a coin. We just need to bring them together. I did some simple math. The size of the Moon, adding to the size of Mercury comes out to be just a little under the size of Mars. Instead of two different glancing impacts around/near Eath's orbit, perhaps it was only one. It created the Eath's Moon, and sent, the now smaller Mercury, into the inner Solar System. I know a lot more research is needed, but perhaps this is a start.

> **Comments:**
> **username_2**: The Great Impact hypothesis is the current favourite theory for the Moon's creation, but there's certainly room for alternate hypotheses. It would be great if we had actual samples of Mercury crust to analyse. It would also be good to do orbit simulations, to see how plausible some kind of Mercury collision scenario is. It  does appear that Mercury has experienced a rather extreme impact: there are what look like fracture lines that converge at the antipodes of the [Caloris](https://en.wikipedia.org/wiki/Caloris_Planitia) impact basin.  
> **username_6**: This does not provide an answer to the question. Once you have sufficient [reputation](https://astronomy.stackexchange.com/help/whats-reputation) you will be able to [comment on any post](https://astronomy.stackexchange.com/help/privileges/comment); instead, [provide answers that don't require clarification from the asker](https://meta.stackexchange.com/questions/214173/why-do-i-need-50-reputation-to-comment-what-can-i-do-instead). - [From Review](/review/late-answers/28465)  

---

