How common are earth-moon planetary systems?

Sep 18, 2011
This illustration shows a potential satellite-forming impact on a proto-planet. Credit: Michael Elser, University of Zurich

Sebastian Elser, Prof. Ben Moore and Dr. Joachim Stadel of the University of Zurich, Switzerland, in cooperation with Ryuji Morishima of NASA's Jet Propulsion Laboratory, tried to estimate how common Earth-Moon planetary systems are. They have found that 1 in 12 Earth-like planets probably hosts a Moon-like satellite. Since the Moon might have played an important role in the history of life on Earth, this estimate is important concerning the search for habitable planets.

Earth's Moon might have played an important role in the development and evolution of life on Earth. The Moon was formed via a giant impact in which a Mars-size projectile collided with the young Earth. The ejected material accumulated in orbit around our planet and formed the Moon. After its formation, the Moon was much closer to Earth than it is today, which caused high tides several times per day. This may have helped promote the very early evolution of life. In addition, a stable climate of more than a billion years may be essential to guarantee a suitable environment for life. But without its satellite, Earth would suffer chaotic variations of the direction of its spin axis, which would in turn result in dramatic variations of the climate.

Therefore, concerning the habitability of , it is reasonable to ask: How common are Earth-Moon ? Sebastian Elser, Prof. Ben Moore and Dr. Joachim Stadel of the University of Zurich, Switzerland, along with Ryuji Morishima of NASA's Jet Propulsion Laboratory in Pasadena, California, ran a large set of N-body simulations to study the formation of the in our solar system via the collisional growth of thousands of small rocky bodies in a disk around the Sun.

They identified numerous satellite-forming collisions during this process and estimated the masses of the generated companions. Moreover, they took into account the orbital evolution of the satellites, since tidal forces change the spin and orbit of a satellite and can cause it to be lost within a few thousand years in the most extreme cases.

Finally, they studied the subsequent collision history, since giant impacts after the epoch of satellite formation may pose a challenge to the survival of a satellite. They find that Earth-Moon planetary systems occur relatively frequently, with more than 1 in 12 terrestrial planets hosting a massive . Uncertainties in the study result in a range of 1 in 4 to 1 in 45. Further work and more N-body simulations are needed to obtain more precise results.

This work is being presented at the Extreme Solar Systems II conference in Jackson, Wyoming, and appears in the August 2011 issue of Icarus.

Explore further: First potentially habitable Earth-sized planet confirmed: It may have liquid water

More information: Journal paper online: dx.doi.org/10.1016/j.icarus.2011.05.025 . Preprint is available: arxiv.org/abs/1105.4616

Provided by University of Zurich

4.9 /5 (15 votes)

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dogbert
2.9 / 5 (10) Sep 18, 2011
It is an important question, but I wonder how accurate any simulation can be. Until/unless our observation skills improve sufficiently to provide us with direct information about bodies around other stars in the habitable zone and the occurrence of double planets of approximately earth/moon size, we are only guessing.
vidyunmaya
1.4 / 5 (19) Sep 18, 2011
Sub:Chandrama-Manaso-Jatah-Chakshuh Surya Ajayata
The evolution of thought-mind region forms a link to
SUN-MOON relation .Here,the observer is on Earth Planet.
If you raise the level of discussion beyond Galactic Plane,one needs to apply similarity principle- and you come to Cosmology Vedas Interlinks- Identify Source,Fields,Flows,
reflectors as a means to Science -Progress Index.Here 12 groups hold special significance.
search:BOOKS BY VIDYARDHI NANDURI © 2011 Vidyardhi Nanduri,all rights reserved
http://vidyardhic...pot.com/
omatumr
1 / 5 (15) Sep 18, 2011
Fragmentation of the central object also seems to be the mechanism that produced planets orbiting the Sun [1-4].

1. "Elemental and isotopic inhomogeneities in noble gases:
The case for local synthesis of the chemical elements",
Transactions Missouri Academy Sciences 9, 104-122 (1975)

2. "Strange xenon, extinct super-heavy elements, and
the solar neutrino puzzle", Science 195, 208-209 (1977)

www.omatumr.com/a...enon.pdf

3. "Noble gas anomalies and synthesis of the chemical
elements", Meteoritics 15, 117-138 (1980)

www.omatumr.com/a...lies.pdf

4. "Solar abundances of the elements",
Meteoritics 18, 209-222 (1983)

http://www.omatum...nces.pdf

With kind regards,
Oliver K. Manuel

PaulRadcliff
1.7 / 5 (6) Sep 18, 2011
moot points, since the formation theory of our Moon's formation, may be incorrect AND the necessity of a satellite has also been called into question, recently, as well. Since we will likely never have the ability to physically travel there, havens for mankind are only workable in generation style starships, which would only be considered if we ruin this planet or an asteroid or comet wipes out life on Earth. Perhaps scientists know something bad is coming for Mankind, and want options????.....
Aliensarethere
5 / 5 (1) Sep 19, 2011
This is a very interesting result, weakening the Rare Earth hypothesis, proposed by Ward and Brownlee in their book from 2000.
kevinrtrs
1 / 5 (16) Sep 19, 2011
The Moon was formed via a giant impact in which a Mars-size projectile collided with the young Earth. The ejected material accumulated in orbit around our planet and formed the Moon.

I really wish people would be more honest and simply state that this is what they THINK happened, instead of presenting it as fact. They weren't there to witness it so it's all just speculation. There's so many variables that need to be just right for this particular scenario to have occurred that it borders on the absolute miraculous.

For example, let's take it as fact - then it might well mean that all the satellites currently circulating the earth are in danger of collapsing into another man-made moon? Wouldn't it have been more probable that the material circulation the earth would have eventually dropped out of orbit instead of coalescing into one big ball? What exactly was required to keep it up there - safely out of the grasp of earths gravity whilst it formed into a nice not-so-round ball?
Aliensarethere
5 / 5 (7) Sep 19, 2011
"There's so many variables that need to be just right for this particular scenario to have occurred that it borders on the absolute miraculous."

The article says quite the opposite.
Ethelred
4.5 / 5 (15) Sep 19, 2011
I really wish people would be more honest
Kevin, why can't you be honest and admit that most of your posts are based on your religion. This time included.

What exactly was required to keep it up there - safely out of the grasp of earths gravity
Orbital dynamics. Much of it must have fallen back to Earth and some material must have been lost as well.

The reason for the idea that the Moon is the result of a collision is that Moon rocks seem to be made of material that might very well have come from the upper layers of the Earth and does not have much iron.

Eyewitnesses are consistently bad sources of information. Heck the Bible can't even get the same last words for Jesus on the cross in all four Gospels and you clearly think that is a perfect document. Physical evidence is far more reliable.

And when was the Flood Kevin?

Ethelred
roboferret
5 / 5 (11) Sep 19, 2011

They weren't there to witness it so it's all just speculation.


There were no witnesses to the creation of the moon in your creation myth either, so I don't get your point. At least this is consistent with physics and observations. Which makes it more than speculation.

There's so many variables that need to be just right for this particular scenario to have occurred that it borders on the absolute miraculous.


As you are someone who is willing to explain the entire universe by the operation of the literally miraculous, I find your incredulity amusing.

Maybe replying to you is a fruitless exercise in fattening an already bloated troll, but I'd hate an impressionable reader to think your hit-and-run intellectual dog foulings were above criticism.
antialias_physorg
5 / 5 (6) Sep 19, 2011
Many stars seem to be part of a binary system. This suggests to me that multiple masses coalescing from available matter clouds is not a coincidence or simply a matter of time but rather a triggered occurence (e.g. by shockwaves from nearby supernovae, passing gravity influences of massive objects like black holes/other suns, etc. )

Is it so speculative to suggest that this goes not only for suns but also for masses that are orders of magnitude smaller (like planet/moon systems)?
The occurrence of planets that have moons could (should?) be about as frequent as that of binary star systems.
omatumr
1 / 5 (13) Sep 19, 2011
Many stars seem to be part of a binary system. This suggests to me that multiple masses coalescing from available matter clouds is not a coincidence or simply a matter of time but rather a triggered occurence (e.g. by shockwaves from nearby supernovae, passing gravity influences of massive objects like black holes/other suns, etc. )

Is it so speculative to suggest that this goes not only for suns but also for masses that are orders of magnitude smaller (like planet/moon systems)?

The occurrence of planets that have moons could (should?) be about as frequent as that of binary star systems.


If the driving force of the universe is is repulsive, rather than attractive (fusion), then fragmentation is to be expected.

"Attraction and repulsion of nucleons: Sources of stellar energy"
Journal of Fusion Energy 19, 93-98 (2001).
http://www.omatum...tnuc.pdf

"Neutron Repulsion", The
APEIRON Journal, in press, 19 pages (2011);
http://arxiv.org/...2.1499v1
antialias_physorg
5 / 5 (14) Sep 19, 2011
Would you kindly refrain from commenting on my posts with your pointless blather?

Thank you so very much.

omatranter
4 / 5 (12) Sep 19, 2011
Thank you for this wonderful research that proves everything I have ever thought.

Fragmentation of my psyche is the main mechanism for my ranting, since the splitting of my personality due to Neutron Repulsion the amount of utter crap I have been able to post on so many sites is astounding, the sewage that I pass off as research should make all of my minions want their mental state to mirror mine, this can only be achieved by believing with every fiber of your being in "Repulsive Neutrons" while drinking the newest product of my astoundingly futile imagination my newest Neutron Repulsion Energy Cool-aide, while clicking your ruby slippers heals together.

Hope to see you at the "Neutron abhorrent Mandated By Laughable Assetions" NAMBLA Conference in October
Ethelred
4.4 / 5 (7) Sep 19, 2011
Since there is no evidence for neutron repulsion beyond that of the Pauli Exclusion Principle why did you bring it up?

Or have you found some of the evidence that absolutely should exist if you were right but have yet to mention?

Ethelred
SpiffyKavu
5 / 5 (4) Sep 19, 2011
...then it might well mean that all the satellites currently circulating the earth are in danger of collapsing into another man-made moon? Wouldn't it have been more probable that the material circulation the earth would have eventually dropped out of orbit instead of coalescing into one big ball?[\q]

The man-made satellites are all in low earth or geosynchronous-earth orbits. The satellites in low orbits are well inside Earth's Roche limit (wiki has an all right discussion on it), so even if all the satellites tried to clump together, the Earth's tidal forces will keep the satellites apart.

The GEO-satellites are well outside this limit, but they do no have nearly enough mass to coalesce via gravity. That, and we keep them all in place with propellant.

And no "force" needs to keep it away from the earth during formation for the same reason why the planets formed, angular momentum is almost exactly conserved.
Ellegan
not rated yet Sep 20, 2011
Due to the fact that Mars has only the two small moons,does Mars suffer from chaotic variations of the direction of it's spin axis?

Also,at what comparative mass of the satellite to the mass of the planet would this chaotic variation direction of its spin axis cause problems with a result in dramatic variations of the climate of the planet?
GSwift7
not rated yet Sep 20, 2011
Due to the fact that Mars has only the two small moons,does Mars suffer from chaotic variations of the direction of it's spin axis?


yes.

Look up precession:

http://en.wikiped...ecession

The gravitational tidal forces of the Moon and Sun apply torque as they attempt to pull the equatorial bulge into the plane of the ecliptic. The portion of the precession due to the combined action of the Sun and the Moon is called lunisolar precession.


Our moon helps to keep our equator aligned with the ecliptic. Mars would have more freedom to move on its own. Mars itself is also smaller and farther from the Sun than we are, therefore allowing for even more freedom.
GSwift7
not rated yet Sep 20, 2011
would this chaotic variation direction of its spin axis cause problems with a result in dramatic variations of the climate of the planet?


As an example, the difference between axial tilt of Earth and Mars is about 2 degrees. On Earth, 1 degree is about 66.6 miles. So two degrees is about 133 miles. So if we were tilted 2 degrees more than we are, the min versus max position of any given spot on the surface, relative to the Sun would be 133 or -133 miles more than what we have now as a result of the Earth's precession. So imagine the effect of changing the location of the equator by 266 miles. It would also make for slightly more severe seasons.

I can't really answer your question, but hopefully I have helped you to form your own ideas about what the answer might be.
omatumr
1 / 5 (6) Sep 24, 2011
Since there is no evidence for neutron repulsion, . . . why did you bring it up?

Ethelred


For those who can read the empirical evidence of neutron repulsion that qualified PhD scientists and editors have reviewed many times [1-5].

1. "Attraction and repulsion of nucleons: Sources of stellar energy", JFE 19, 93-98 (2001)
www.omatumr.com/a...tnuc.pdf]www.omatumr.com/a...tnuc.pdf[/url]

2. "Nuclear systematics: III. The source of solar luminosity", JRNC 252, 3-7 (2002)

www.springerlink....ak3lyrc/

3. "Implications for solar eruptions and climate", JFE 21, 193-198 (2002)

http://arxiv.org/.../0501441

4. "The standard solar model versus experimental observations" IOP Proceedings (editor: H. V. Klapdor-Kleingrothaus) pp. 307-316 (2003)

http://arxiv.org/.../0404064
www.omatumr.com/a...tnuc.pdf]www.omatumr.com/a...tnuc.pdf[/url]

Etc.,

5. "Neutron Repulsion", The APEIRON Journal, in press (2011)

http://arxiv.org/...2.1499v1
Ethelred
3.7 / 5 (3) Sep 25, 2011
For those who can read the empirical evidence of neutron repulsion that qualified PhD scientists and editors have reviewed many times [1-5].
I and others have read those. Noting in them shows anything that isn't covered by the Pauli Exclusion Principle or standard astro-physics.

qualified PhD scientists and editors have reviewed many times
And none of them agree with you on Neutron Repulsion. Not one citation except by you. Not one supporting letter, document, or paper.

Where is the EVIDENCE that supports you. Or even SOMEONE that supports you. Your students don't. And that one table is not support. It was work done to get a grade by people that have NOT supported you and did not write the conclusion as that was yours.

Repeating stuff that does not show a difference between the PEP and your idea is not support for your idea. Something someone ELSE said is needed and it too needs to show something to differentiate it from the PEP.

Ethelred

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