EP307: Louis Frank Snowballs and Condensation of Interplanetary Matter
Ben Franklin Centre for Theoretical Research
PO Box 27, Subiaco, WA 6008, Australia.
Matter between the Planets
Over the years, we have gained a great deal of information about the planets of our Solar System, and of smaller items such as moons, asteroids, dwarf planets, and comets. This has been both through improved telescopic methods, and through the use of space probes, with cameras and instruments which have passed by many bodies and landed on a few.
But our knowledge of the smallest items, such as small balls of ice, and dust particles, is much more limited. What we do know about is mostly from comets, which are usually aggregations of ice, frozen gases, and dust which sweep in from remote distances beyond the edge of the Solar System . The Solar System can be regarded as a sphere of radius 100 AU, where 1 AU (Astronomical Unit) is the Earth-Sun distance; the major planets lie in an approximate plane, extending out some 30 AU from the Sun.
Fig. EP307-F1. The Heliosphere. From .
Comets which become visible in the skies do so because, as they approach the Sun, the Sun's heat begins to volatilize some of the frozen gases and ice which they contain in their nucleus, and the released material streams out in a tail behind them, reflecting enough sunlight to make them visible. The tail starts to form by the time the comet comes within about 5 AU of the Sun -- at about the distance of Jupiter.
Fig. EP307-F2. A comet and its tails. From .
So formation of a tail is a destructive process, because it involves loss of material from the comet's nucleus. This is why a comet which reappears at regular intervals, such as Halley's Comet, gradually gets fainter with each appearance -- it has less mass each time to be dissipated.
Spacecraft have visited the nucleus of some comets, and even analyzed their composition. They usually have a "rocky" core, but as its density is only about 0.6 gm/cc, less than that of ice, these cores are believed to be rather loose aggregates of ice and dust, rather than solid rock.
The relevance of comets to this article is that they are one of the sources of the thin fog of matter which can exist in interplanetary space.
The term "asteroids" refers to small rocky bodies which are in orbit around the Sun. They are predominantly found in the "Asteroid Belt", a region lying between the orbit of Mars and that of Jupiter.
As with comet nuclei, the structures and densities of asteroids appear to vary quite widely. The largest, Ceres, has a density calculated at at approximately 2.0 gm/cc, while the smaller Pallas and Vesta have densities calculated at 4.4 and 3.9 gm/cc . Surface rocks on Earth have densities mostly between 1.6 and 3.5 gm/cc, while ice has a density of about 0.9 gm/cc.
So in essence, asteroids appear to be the same sort of thing as larger comets, but comets which have lost much of their easily-volatile material to space. They may still contain varying amounts of water or ice, but this is trapped inside a rocky skin.
Dust and meteorites from space
We know that the Earth is in in continuous receipt of bodies falling from space, most notably in the form of meteorites. According to , estimates for the mass of material that falls on Earth each year range from 37,000 to 78,000 tons. Most of this mass would come from dust-sized particles.
Meteors can be seen in the night sky on most nights, meteorites have enough mass and cohesion for recognizable masses to reach the ground. Many meteors "break up" or "burn up" in the sky -- they are bright because particles breaking off burn under air friction -- and only their burned dust reaches the ground.
It seems that dust particles exist as such in interplanetary space. In 1999, NASA launched the "Stardust" space probe which collected dust from interplanetary space and from a visit to the comet "Wild 2", and in 2006 dropped a capsule containing the dust samples back on Earth .
Fig. EP307-F3. NASA's Stardust spacecraft carried comet and interstellar particles back to Earth in January, 2006. From .
These dust samples are still being analyzed, but have enabled researchers to discover a new class of organics, captured by the dust particles, that was more primitive than those spotted in meteorites. Scientists also found irregular particles known as calcium-aluminium-rich inclusions (CAIs). CAIs are among the oldest solar system materials .
Particle emissions from the Sun
There are two main mechanisms by which matter is injected into interplanetary space by the Sun. The first is the Solar Wind.
According to , the solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between 0.5 and 10 keV. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field.
Fig. EP307-F4. The solar wind encountering Earth's magnetic field. From .
Because the Earth has a substantial magnetic field, a portion of the Solar Wind particles are diverted around it. Although emitted at high speeds from the Sun, the particles slow down as they move into interplanetary space, and the Solar Wind ceases before it reaches the Heliopause (the sphere of radius about 100 AU which contains the planets and an outer region called the Kuiper Belt).
The second mechanism involves Solar Flares and associated Coronal Mass Ejections. Solar flares are closely associated with the ejection of plasmas and particles through the Sun's corona into outer space; flares also copiously emit radio waves . With Coronal Mass Ejections, a plume of material is injected into space from the Sun in a particular direction. Some CMEs happen to hit the Earth, causing auroras and sometimes radio disruption.
Fig. EP307-F5. Coronal Mass Ejection on August 31, 2012. From .
Both the Solar Wind and Solar Flares put matter into interplanetary space. Although the amount added may be small on an annual basis, these effects have presumably been continuing since the Sun was born, over 4.5 million years ago.
Loss of planetary atmospheres
We know quite a lot about the atmospheres, or lack of atmosphere, of the planets, moons, and asteroids of the Solar System.
Although not known with certainty, there is a reasonable case for assuming that all the planets started off with similar atmospheres. It then appears that the very varying planetary atmospheres today are due to varying losses of components of these atmospheres. In the case of Earth, our atmosphere has also undergone large changes in the distant past due to action by living organisms.
Whether an atmospheric component is liable or not to escape depends on its molecular mass and the temperature of the part of the planet where it is situated. This liability depends on what's called the molecule's Escape Velocity. Lower-mass and lower-density planets have lower values for these escape velocities.
Fig. EP307-F6. Atmospheres of planets and moons in the Solar System. From .
The above figure shows graphs of escape velocity against surface temperature of some Solar System objects, showing which gases are retained. The objects are drawn to scale, and their data points are at the black dots in the middle .
The general picture is that the outer four planets are massive (and cold) enough that they have retained all their original gases, including Hydrogen (Molecular weight=2) and Helium (MW=4). Earth is massive enough to have retained most of its water vapour (MW=18), nitrogen (MW=28), oxygen (MW=32), and Argon (MW=18).
Carbon dioxide (MW=44) is also retained, though it forms part of the life cycle and its fraction of the atmosphere varies accordingly. There is a good table of the atmosphere's current composition at . The atmosphere does contain tiny amounts of helium and free hydrogen, these will be rapidly lost, but are replaced by various minor processes.
Venus is only a little warmer and smaller than Earth, but it now has a completely different atmosphere, about 90 times as dense as Earth's. Venus has lost almost all its oxygen, nitrogen, and water vapour, and its atmosphere is almost entirely carbon dioxide (MW=44). On Earth, life processes have locked up most of our carbon in carbonate rocks, but as Venus never had life, its carbon is in its atmosphere. Mercury and our Moon are small, with low escape velocities, and have no atmospheres.
There are a number of processes by which atmosphere is lost from planets, as described in . In the main one, "thermal escape", escape occurs when molecular kinetic energy overcomes gravitational energy; in other words, a molecule can escape when it is moving faster than the escape velocity of its planet. But because the gas molecules have a range of speeds, even for the same type of molecule, some moving faster and some slower than average, there will always be the possibility of partial loss of the faster molecules.
The importance of loss of atmosphere from planets here, is that all the losses don't just disappear, but add to the thin interplanetary fog of matter. This interplanetary fog is not fixed, but is is dynamic equilibrium, with material being added and subtracted all the time. We've already seen how meteorites represent one of the ways the interplanetary fog loses matter, we can go on now to look at another major, but little-known, effect.
Louis Frank's Snowballs
During the 1950s, an American scientist named Louis Frank came across a puzzling feature of atmospheric science which would eventually lead to an astonishing new fact about the Earth. Our planet is under bombardment by house-sized balls of water ice, not occasionally, but sometimes as often as 20 times a minute.
Frank described his discoveries, and the considerable doubts which he had to overcome to get them accepted, in his 1990 book "The Big Splash". This book is worth reading both for the story of his discoveries and for a gritty account of the realities a new discovery faces when it comes up against the established world.
Fig. EP307-F7. Cover of Louis Frank's book "The Big Splash". From .
These balls, which Frank called "Small Comets", weigh as much as 100 tons each. In the book he says "A small comet falls into the Earth's atmosphere about every 3 seconds. Each one contains about 100 tons of water. Some 25,000 such objects fall to the Earth each day, or about 10 million on average over the course of a year".
These figures were startling enough to cause a genuine reaction to their acceptance. Ten million objects each weighing 100 tons represents a billion tons a year. If the Louis Frank Snowballs were actually adding a billion tons to the Earth's mass each year, there would be major ramifications.
One of these concerns the topic of where Earth's water comes from. The traditional idea is that it was boiled out of the Earth's rocks during a very long geological history, extending over 4.5 billion years. But although there is an awfully large amount of water on Earth (about 1.26 trillion tonnes), if LFSs were adding a billion tons a year over the Earth's history, this would be much more than we calculate exists in the present oceans and water bodies!
Frank speculated that his Small Comets came from the Oort Cloud, which, after all, is the source of almost all the objects we regard a comets. But he noted that such a source did not fit in with observed motions -- these objects circle the Sun in the same direction and in about the same orbital planes as the planets, whereas real Oort Cloud objects appear with orbits quite random to this plane. Frank also showed that incidence of the snowballs was greater on the leading side of the Earth as it moved in its orbit. In addition, the LFSs appeared to made up of pure water, without the dust component which characterizes real comets.
Fig. EP307-F8. Atmospheric hole cause by a "small comet". From .
Frank's work was rejected or ignored for many years. Finally, in April 1986, Frank's discovery was reported in the journal "Geophysical Research Letters", with a cover picture showing the hole in the atmosphere produced by one of his "small comets". This picture is in , with the following caption.
"The ring at the top of the ultraviolet image is the northern auroral ring.The inset is an expanded view of an "atmospheric hole" produced by a small comet. This black spot actually represents a cloud of water vapor about 30 miles in diameter at an altitude in the range of 200 to 600 miles above the Earth's surface. This is what remains of a small comet when the house-sized chunk of water-snow is vaporized above the Earth's atmosphere".
So the reason why these huge snowballs falling on the Earth have not been widely recognized is because they generally vaporize in the very highest layers of our atmosphere, and just add to the stock of water vapour which is a common constituent of the atmosphere.
The existence of Frank's "small comets" is no longer disputed, but the mystery of where they originate, and their effect on Earth's water balance, has till now remained unsolved.
The Megacryometeor Puzzle solved!
A meteorological phenomenon which has baffled scientists in the past is that of "megacryometeors" -- large chunks of ice weighing as much as 50 kg, which fall to Earth out of cloudless skies. Here is an extract from what Wikipedia says about them .
"A megacryometeor is a very large chunk of ice which, despite sharing many textural, hydro-chemical, and isotopic features detected in large hailstones, is formed under unusual atmospheric conditions which clearly differ from those of the cumulonimbus cloud scenario (i.e. clear-sky conditions). They are sometimes called huge hailstones, but do not need to form under thunderstorm conditions.
More than 50 megacryometeors have been recorded since the year 2000. They vary in mass between 0.5 kg to several tens of kilograms. One in Brazil weighed in at more than 50 kg. Chunks about 2 m in size fell in Scotland in 1849. In January 2000, ice chunks weighing up to 3.0 kg rained on Spain out of cloudless skies for ten days.
The process that creates megacryometeors is not completely understood, mainly with respect to the atmospheric dynamics necessary to produce them. They may have a similar mechanism of formation to that leading to production of hailstones. Scientific studies show that their composition matches normal tropospheric rainwater for the areas in which they fall. In addition, megacryometeors display textural variations of the ice, and hydro-chemical and isotopic heterogeneity, which evidence a complex formation process in the atmosphere. A detailed micro-Raman spectroscopic study made it possible to place the formation of the megacryometeors within a particular range of temperatures: -10 to -20 deg C".
Fig. EP307-F9. 2018 Canada Megacryometeor. From .
It will be obvious, from what we know of Louis Frank Snowballs, that Megacryometeors are merely LFSs which are large enough to survive complete vaporization, as they fall from the outer atmosphere to the Earth's surface.
Support for this conclusion comes from the shape and outer skin of megacryometeors, which are invariably fairly smooth and often of flattened ovoid form, like meteorites which have had their outer layer melted and sloughed off, such as tektites.
The real origin of Louis Frank Snowballs
We are accustomed to think of the Earth as a globe isolated in space, not subject to large changes in mass or energy (temperature). In fact, it is really in a state of dynamic equilibrium -- both energy and mass are being added to and being lost, but these changes are usually in balance, in equilibrium.
A huge amount of energy reaches the Earth from the Sun each day, and a little comes from the planet's internal processes. An exactly equal huge amount is lost from the Earth each day, radiated away as infrared. This topic is covered in Temperatures of the Earth -- a Globe in Space . A change in the equilibrium, a shift in the balance point, only occurs when there is alteration to the input/output quantities.
The level of matter transfer is smaller, but still significant. We have seen that the Earth gains solid matter, in the form of meteorites and space dust, amounting to 37-78 thousand tons a year. Some dust is probably lost to space from the occasional giant volcanic eruptions, which can shoot volcanic ash particles 40 km high in the atmosphere. The biggest matter input is the Louis Frank Snowballs, which can amount to a billion tonnes a year.
This input is evidently matched by a similar output -- the loss of water vapour into space from the edges of our atmosphere. In this scenario, Earth's orbit contains an extensive ring of thin mist, through which we plough each day, pulling in the LFSs sitting in the mist ring.
The situation may be similar to that around Jupiter. As it proceeds along its orbit round the Sun, Jupiter is followed and preceded by two strings of tiny asteroids, called Trojan groups.
Fig. EP307-F10. Trojan asteroids in Jupiter's orbit. From .
In a similar way to Jupiter, it appears that Earth may have Trojan strings of LFSs, condensed out of water vapour which has escaped from our atmosphere. In the figure, the gravitational dynamics are such that Jupiter has drawn in any closer Trojans, clearing its orbit by its gravitational pull. With the much smaller mass of the Earth, the mist ring of LFSs in Earth orbit may be more continuous, like the Asteroid Belt which exists between the orbits of Mars and Jupiter.
Several factors from what we have already seen of LFSs and Megacryometeors do support this picture. These factors include that LFSs appear made of pure water, without normal comet dust; that Earth appears to be running into bodies sitting in its orbit, since LFSs are more frequent on its leading face; and that LFSs were calculated to have formed at a temperature of minus 10 to minus 20 degrees Centigrade, which is exactly the average temperature of isolated bodies (such as the Moon) at Earth's distance from the Sun.
There is a parallel to LFSs elsewhere in the Solar System, in Saturn's Rings. These also appear to be largely ice balls with a little dust, up to 10 metres in diameter. And in an analogue to Earth, within the Rings are tiny moons called "Shepherd Moons", which move with the orbits of the Ring objects.
Mechanics of condensing objects in planetary orbit
We now know that quite a lot of matter exists in interplanetary space, originating from loss of planetary atmospheres, emissions from the Sun, and perhaps other sources. The forms of this matter are not currently known with any degree of certainty -- some obviously exists as dust, other as gas or vapour, and some has aggregated into solid masses, as with the LFSs.
What are the forces acting on this interplanetary fog or mist? Clearly a major force is Gravity. The aggregation of interstellar matter into planetesimals, bodies of every size, from a few kilometres up right to massive stars, is evidenced in P1: The Cosmic Smog model for solar system formation . The same forces of aggregation can be assumed to occur with interplanetary matter, if on a smaller scale. After an initial body is formed, it can be assumed to accumulate more matter from its surroundings, increasing in mass and gravitational attraction, until it has sucked in everything within its gravitational pull.
Another factor affecting clumping in a thin distribution of matter is when it is subject to incoming radiation bursts or other physical waves. The quotation at the head of this article relates to star formation in interstellar gases -- pressure waves on gases in space can encourage their aggregation into dense new star-fields.
Fig. EP307-F11. Particle movements in standing waves From .
On a smaller scale, a similar phenomenon can be seen if a tray of sand is subjected to a sound-wave of a particular wavelength, called a standing wave. The sand particles shift together and apart, clustering in bands one wavelength apart. Matter clouds in interplanetary space may be subject to some such aggregating influences, apart from gravity.
Another factor to be considered is that of Equatorial Forcing. Simple Newtonian gravity theory adequately explains most astronomical body movements, but not all. The standard formula gives the gravitational force between two bodies as equal to the product of their masses divided by the square of the distance separating them. It does not consider the effects of rotation of these bodies, which shows up in such things as tides, and ultimately determines why Solar System planets lie almost in a single plane, and why the Milky Way and other galaxies are disc-shaped rather than globular.
In the case of LFSs, a question which might be asked, is why do they appear to sit in the orbit of Earth, so that the planet collides with them as it progresses, rather than the LFSs orbiting at the same rate as the Earth? Gases in Earth orbit do not have the requirement to orbit the Sun like a planet, they do not behave like a solid body whose position has been established slowly over millions of years through Equatorial Forcing.
Equatorial Forcing is a neglected area of gravity research -- there is an explanation of it at XT806: What is Equatorial Forcing?. . One area where it does figure prominently is with space probes, which are routinely accelerated in their passage by applying swing-by or gravity assist against planets, sometimes several times. Gravity assist depends on the rotation of a planet, not its mass. There is more on this in .
The whole field of aggregation or condensation of matter in space deserves a lot more attention, what has been described above only skims the surface. A particular area meriting more research is the formation of LFSs as revealed in macrocryometeors -- these cores may show layering which could reveal how long they took to build up in space.
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References and Links
. Atmospheric Composition. http://www.physicalgeography.net/fundamentals/7a.html .
. Comet nucleus. https://en.wikipedia.org/wiki/Comet_nucleus .
. The flashy lives of comets. http://lasp.colorado.edu/outerplanets/kbos_comets.php .
. New masses calculated for 3 largest asteroids. https://nssdc.gsfc.nasa.gov › planetary › text › asteroid_pr_980109 .
. How many meteorites hit Earth each year?. http://curious.astro.cornell.edu/about-us/75-our-solar-system/comets-meteors-and-asteroids/meteorites/313-how-many-meteorites-hit-earth-each-year-intermediate .
. Nola Taylor Redd. NASA's Stardust Mission: The Space Probe That Brought Stardust to Earth. https://www.space.com/stardust-mission.html .
. Solar wind. https://en.wikipedia.org/wiki/Solar_wind .
. Solar flare. https://en.wikipedia.org/wiki/Solar_flare.
. Louis A. Frank with Patrick Huyghe. The Big Splash. Birch Lane Press, 1990. ISBN 1-55972-033-6.
. Atmospheric escape. https://en.wikipedia.org/wiki/Atmospheric_escape .
. Heliosphere. https://simple.wikipedia.org/wiki/Heliosphere .
. Megacryometeor. https://en.wikipedia.org/wiki/Megacryometeor .
. Beatrice Vaisman. Megacryometeor? Mystery stirs over large ice chunk found in Alliston . https://barrie.ctvnews.ca/megacryometeor-mystery-stirs-over-large-ice-chunk-found-in-alliston-1.3772604 .
. David Noel. Temperatures of the Earth -- a Globe in Space (a re-analysis with some surprising results). http://www.aoi.com.au/bcw/EarthTemp/index.htm .
. Asteroid belt. https://www.spacetelescope.org/images/heic1715c/ .
. Standing Waves. http://www.sengpielaudio.com/StandingWaves.htm .
. David Noel. XT806: What is Equatorial Forcing?. http://www.aoi.com.au/Extracts/XT806.htm .
. David Noel. P1: The Cosmic Smog model for solar system formation, and the nature of 'Dark Matter'. http://www.aoi.com.au/bcw1/Cosmic/index.htm .
. Gravity assist. https://en.wikipedia.org/wiki/Gravity_assist .
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Compilation started 2019 Aug 28. First version on Web, 2019 Oct 23.