A Moon For All Seasons
Posted by xbanguyen on February 20, 2012
The night wasn’t so dark nor the horizon so stark when I returned and almost ran into a large moon hovering low behind the oak tree guarding the driveway down the street. I forgot how large the moon could appear. Tired after a long day, I yielded to all the crescents in my past, letting them break from their mooring to be suffused with this silvery light. Hackneyed though it may sound, it has got to be called silvery, you would agree too if you saw it. It did appear to be very close, close enough not to be jarred by the thought that for a brief time we were one. For it is theorized that a Mars-size planet collided with our earth when it was young with both planets’ mantles comprised of silica and their cores iron. 
The force of the collision was so great that the errant planet almost destroyed the earth, piercing through earth’s core, leaving almost all of its iron [1] . The earth endured and the moon emerged, sans iron, from the collision not unlike the phoenix rising from its ashes. Did you know that the moon is younger than its previously estimated age of 4,56 billion years? Just last August, an international team of US, French and Danish scientists announced a new technique of measuring the isotopes of lead and neodymium in a piece of rock brought back from the Apollo 16 mission to show that our moon is only 4.36 billion years old, the same age as the zircon found in Australia[2] . The mind’s comprehension of such large number adds a kind of permanence to the silvery light and I am glad.
Gladness is not the prevalent emotion I’ve found in moon-inspired poems. For beside exerting gravitational force on our waters to cause tides, the moon is also a force that leaves her marks in many poems. I could not choose just one so I’ll settle with couplets and stanzas of several much-admired poems that came my way and stayed – the one from Dylan Thomas has been with me for quite some time, Alicia Stallings’s makes formal meters appear illicitly daring. I can’t resist the juxtaposition of the stalking and therapeutic presence of the moon in the other excerpts, the rhythm of Emily Dickinson’s, nor let this post be unadorned by the prettiness of Joseph Eichendorff’s simile describing the shimmering light. And I wonder how it feels to unfold moonbeams.
The poetic pleasure indulged thus far is complemented by the fact that the moon has no atmosphere, but only a thin exosphere – a cubic centimeter of Earth’s atmosphere at sea level contains about 100 billion billion molecules whereas that same volume of the Moon’s exosphere contains only about 100 molecules[3] . Not only that, during the lunar night, this exosphere falls to the ground, sleeping perhaps. Because of this lack of atmosphere, footsteps left on the moon will last millions of years. Forever can’t be measured but relative permanence is possible, as long as the heliosphere endures to save us from the unrelenting intergalactic radiation.
Thank you for helping me choose, dear muse.
Acknowledgement
[1] http://burro.astr.cwru.edu/stu/earth_moon.html
[2] http://www.sciencedaily.com/releases/2011/08/110818093046.htm
[3] http://science.nasa.gov/science-news/science-at-nasa/2009/23oct_ladee/
[2] http://www.sciencedaily.com/releases/2011/08/110818093046.htm
[3] http://science.nasa.gov/science-news/science-at-nasa/2009/23oct_ladee/
[4] The moon formation photo is from http://news.nationalgeographic.com/news/bigphotos/49530832.html
[5] The tide diagram is from http://www.sciencebuddies.org/science-fair-projects/project_ideas/Astro_p009.shtml
[6] The heliosphere photo is from http://www.nasa.gov/images/content/274844main_DaveHeliosphereFlippedVis4Lg.jpg
[7] The full moon photo is from http://www.dipity.com/tickr/Flickr_moons/
[8] With apologies to the poet A.E. Stalling for the fragmented quote of her poem.
An Engineer's Literary Notebook 
wesley wozniak said
Liquid Dynamics in Planetary Formation
The accretion process works on all planets. The unasked question is, what is the largest thing ever accreted, absorbed by, or impacted on a gas giant planet in our solar system? Has Jupiter absorbed planets larger than earth? What are the dynamics of such an event? What is the result?
I believe that during such an event, the massive planets would follow common physical laws of liquid dynamics creating a massive splash/crater, and a Worthington Jet to scale. A Worthington Jet of that scale could leave a droplet of molten material (a moon) in orbit. We can look to craters, such as Theophilus, on our own moon, to see a common example of a central peak left behind by Worthington Jet forces working on solid rock. Crater chains, are also clear indications of this type of event.
Being deposited in orbit in that way, the molten material would be able to differentiate it’s core, from it’s crust. The core of molten metal would be drawn slightly toward the planet it now orbited. This off center core would act like a ballast keeping the moon from ever being able to rotate that bottom side away form the parent planet.
If we look at water splashes here on earth, we can see that sometimes the Worthington Jet results in multiple droplets as the surface tension of the material seeks least resistance. I believe multiple moons may be created from a single impact and jet. These moons would be siblings. Later, that gas giant might absorb another planet, and get more moons. Those moons might share characteristics of the planet absorbed. This might explain the wide differences between the elemental components of moons that orbit the same planet in a way that the current theory, (that these moons are accreted from the same rings of dust, stone, and ices) does not..
As a Worthington Jet collapses back toward the larger planet, a secondary splash may also propel smaller droplets into possible orbital trajectories.
If Jupiter’s moons, Io, Europa, and Ganymede, were created from the same Worthington jet, the tidal pull of the surface rushing by underneath them would impart a greater and greater orbital rotation in ration to their mass, and distance from Jupiter. The result of this would be a faster orbit for moons that are closer to the the parent planet they orbit.
Could the rocky inner planets be escaped moons of gas giants? If a moon escaped orbit with Jupiter, or any other gas giant planet, it should have a much more elliptical, comet like, orbit. So here is an event function. When a sun ignites, it creates a powerful solar wind. This wind would act like a retro rocket on in bound objects, and might be just enough to arrest a few lucky rocky bodies into a long term orbit.
If the Earth moon had been spinning much as Pluto and it’s moon do, what would the resulting resistance have been on the two inbound masses, and how would it have affected the orbital relationship between them?
It may well have been the coming together of two like sized planets, that made first contact at north and south poles, that resulted in the planet Uranus with it’s axis of spin almost perpendicular to that of the sun. The masses of the two large planets spinning around each other as they merged. Saturn also fits well within this model. Would there also be vertical ejecta resulting from a gas giant falling into the Sun?
As a molten moon boils off it’s volatile elements, it would seed an icy ring around its new parent planet. These volatile elements could then be reabsorbed by other moons that had cooled down. As the volatile boiling off phase takes place, the tidal forces exerted by the parent planet would cause the convection to orient toward that parent planet as the escaping gases seek the path of least resistance. This would cause the slag, like that in glass or metal refineries, to float away form the parent planet and gather on the far side of that moon. This would also help to off set the metal core, increasing it’s likelihood of acting as a ballast. As our moon has suffered some massive impacts that have caused molten lakes that are now “the face of the moon” the propagating waves created by those impacts could have traveled all the way to the back of the moon where they “jacked up” or the wave force becomes amplified as it comes together in a smaller surface area.
A clip of Astronaut Don Pettit on the ISS working with a large free floating sphere of water.
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xbanguyen said
I also read somewhere that there were two earth moons at some point but was not clear on how the two moons became one, or perhaps one was absorbed by falling into earth, and that traces of water was found on earth moon’s soil samples. Not sure about the implication of that finding. Thank you for a very cogent explanation of planet formations. By the way, I like the word “accretion” in both poetic and scientific contexts.
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wesley wozniak said
A better zero G impact with body waves. sec. 1.08 shows a good example of a worthington jet launching a droplet. The surface tension seems to help stabilize the vertical ejected droplet in a way that could evolve into an orbital resonance.
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