ICE RING: An artist’s conception of the disk around the young star TW Hydrae shows the presumed location of abundant water ice in blue. Image: NASA/JPL-Caltech
To become a world bathed in oceans of water and habitable, Earth first had to take a beating. A popular hypothesis holds that icy comets and asteroids pummeling early Earth delivered the planet’s water from the icy outer reaches of the solar system.
Rocky, terrestrial worlds in other planetary systems might become watery by the same process, but assessing just how much ice is available to distant, newborn planets has been challenging. With the help of the European Space Agency’s Herschel Space Observatory, however, astronomers have gotten a good look at the seeds of a planetary system around a young star 175 light-years away, and there seems to be plenty of water to go around.
The researchers used Herschel to scan the protoplanetary disk around the 10-million-year-old star TW Hydrae, one of the nearest such disks available for study. (Protoplanetary disks are the swirling pancakes of dust and gas surrounding young stars that can coalesce over millions of years, as the sun’s disk did, into terrestrial planets and gas giants.) The astronomers reported in the October 21 issue of Science that they picked up a faint signature of water vapor from TW Hydrae’s disk, which they presume emanates from a much larger reservoir. The icy outer portion of the disk probably contains enough water to fill Earth’s oceans thousands of times over, the researchers estimate.
Locating faraway reservoirs of water is generally hampered by the abundant water vapor in Earth’s own atmosphere, which clouds the view of ground-based telescopes. That is not a problem for Herschel, a large far-infrared/sub-millimeter–spectrum telescope stationed 1.5 million kilometers from Earth, well beyond the orbit of the moon. From its unobstructed vantage point, Herschel’s spectrometer located a small amount of water vapor coming off of TW Hydrae’s dusty protoplanetary disk at a distance of roughly 100 astronomical units, or 100 times the Earth–sun distance, from the star.
The very presence of vapor so far from TW Hydrae points to an interaction between the star’s radiation and the ice in the disk. “We know that at these distances the temperature is so low that it should be frozen,” says lead study author Michiel Hogerheijde, an astronomer at Leiden Observatory in the Netherlands. But ultraviolet (UV) radiation emanating from TW Hydrae should liberate some water molecules from icy dust grains in the protoplanetary disk, in a process known as photodesorption.
Having measured how much water vapor is produced by photodesorption, Hogerheijde and his colleagues were able to fashion a rough estimate of the amount of ice present in the disk. “We know the efficiency of this photodesorption process very well,” he says. “We know that we need to have an underlying reservoir of several thousands times Earth’s oceans to produce this small amount of vapor.”
TW Hydrae joins a small number of nascent planetary systems that have been found to contain water in some form, either as hot vapor close to the star or as cold ice in the outer protoplanetary disk. In those past instances, though, it has been “relatively hard to actually quantify how much water ice was present,” Hogerheijde says. “We’ve always thought that there should be a large amount, but we just didn’t know, because there’s no data.”
With a relatively clear look at one planetary system to compare with our own, astronomers can now more confidently ponder the existence of distant, watery worlds. For if TW Hydrae develops rocky worlds, there should be plenty of icy leftovers on the outskirts of the planetary system to supply those worlds with water, in much the same way that comets and asteroids may have provided for Earth billions of years ago. “If the mechanism that delivered Earth’s oceans happened here, it may be happening in other solar systems as well,” Hogerheijde says.
So my title this time is a pretty strong one, where does the water on our planet come from? That’s a big, very big question, yet a totally fundamental one too, what the physics research people call, a serious query.
Here I am studying cerebral concussions, so what does water have to do with getting ‘bonked on your noggin’? Pretty much everything I would say. First off, our bodies are practically all water, our blood has the same component ratio as from ancient oceans. Our brain sits in a pool of water-like fluid, cerebral spinal fluid, (CSF). My last post on the woodpecker blog concludes- these head hitting birds don’t get concussions because they have minimal CSF surrounding their brains, so water has a lot to do with the motion of the brain during a concussion.
One of the guiding books in my own little library was found earlier this year during my sabbatical search. The book is titled Sensitive Chaos by Theodor Schwenk. I still get goose bumps when I flick open the book. Its spoken passages are lyrically magical describing the movement of water in a majestic, sweeping fashion as if from a book of poetry. I get enormous inspiration from the tight poems containing Schwenk’s explanations. Everything I am currently doing, by trying to understand concussions this sabbatical year comes down to Schwenk’s water analysis, his singular vision trying to fathom the meaning of, water in motion.
Let’s break the ice by listening to the eloquent words describing being in water with Jacques Yves Cousteau. “Off the island of Alboran, above the forests of gigantic laminarians, I dived at night with Falco in the stream of Atlantic waters rushing into the Mediterranean at the speed of three knots. Under the keel of Espadon we drifted along with our floodlights: all around us there arose from the living sea a hymn to the ‘sensitive chaos’ – (Novalis Fragmente). The vast culture medium was swarming with clusters of eggs, transparent larvae, tiny, faintly colored crustaceans, long Venus girdles which a single gesture could wind at a distance, crystal bells indolently pulsating, turned by our lights into glittering gems. The salps, small barrel-shaped forms consisting of organized water, were joined together into trains sixty or ninety feet long, their transparency punctuated by the minute orange dots which are at the core of each individual. All that life around us was really water, modeled according to its own laws, vitalized by each fresh venture, striving to rise into consciousness.”
Let me take some descriptive words from the back cover of Sensitive Chaos, strategically to give a brief, compact overview.
“Why does water always take a winding course in streams and rivers? Do common principles and rhythms underlie its movement-whether it be in the sea, in a plant, or even in the blood of a human being?” Here’s some more…
“In this original and thought provoking work, the laws in the subtle patterns of water in movement are shown to be the same as those perceptible in the shaping of bones, muscles and a myriad of other forms in Nature. Sensitive Chaos reveals the unifying forces that underlie all living things.(that is my emphasis) Schwenk observes and explains such phenomena as the flight of birds, the formation of internal organs such as the heart, the eye and the ear, as well as mountain ranges and river deltas, weather and space patterns, and even the formation of the human embryo.”
“The water vortex is finely laminated, layer upon layer.” p.50
“Everywhere liquids move in rhythms. Countless rhythms run through he processes of nature. Not only are the great currents and tides of he oceans subject to the rhythms of the seasons; every lake, every pond, every well with it’s ground-water level has its movements that fluctuate with high and low tide or according to other laws.”
“Wherever water occurs it tends to take on a spherical form. It envelops the whole sphere of the Earth, enclosing every object in a thin film. Falling as a drop, water oscillates about the shape of a sphere; or as dew fallen on a clear and starry night it transforms an inconspicuous meadow into a starry heaven of sparkling drops. We see moving water always seeking a lower level, following the pull of gravity. In the first instance it is Earthly laws that cause it to flow, draw it away from its spherical form and make it follow a more or less. It finds many ways of maintaining a rhythmical balance between the spherical form natural to it and the pull of Earthly gravity.”
“A sphere is a totality, a whole, and water will always attempt to form an organic whole by joining what is divided and uniting it in circulation. It is not possible to speak of the beginning or end of a circulatory system; everything is inwardly connected a reciprocally related. Water is essentially the element of circulatory systems. If a living circulation is interrupted, a totality is broken into and the linear chain of cause and effect as an organic law is set in motion.”
“The cycle through the solid, liquid and gaseous phases may be counted the best known circulatory processes of water. Rising from oceans, lakes and rivers, it circulates with the air in the great atmospheric currents around the Earth. Where it enters cooler zones, for instance when rising to pass over a mountain range, it contracts into clouds and falls back to Earth as dew, rain, snow or hail. But only a small part- a little more than a third of the precipitation-finds its way to the sea in streams and rivers. The rest dissolves again into the atmosphere and continues on in the great wandering course of the low pressure areas or other air currents. In this way water completes a circulation from liquid through vapor back to liquid, which it repeats about thirty-four times during the course of a year. Whether hurrying towards the sea in river, whether borne by air currents or falling to the earth as rain or snow-water is always on the way somewhere at some point in one of its great or small circulatory systems. Having seemingly arrived at its goal in the sea, it is swept on by the great ocean currents, in which it continues in its circulation on the surface or in the depths. Currents of gigantic proportions fill the depths of the oceans. The extent of these huge currents is shown by the fact that the oceans account for about 71 percent of the surface of this Earthly planet. When cooled to its temperature of greatest density, 4 c., water sinks (in salt water conditions are somewhat modified), while warmer water from the depths rises to the surface. On the ocean bed the huge masses of water that have sunk in the polar regions roll toward the equator, and later in far distant places return again to the surface.”
“The plant world plays a special part in the great circulation of water. As plants consist mainly of water an immense stream transpires into the atmosphere from fields, meadows and woodlands. On a summer’s day a 40,000 litre stream of water is drawn through a hectare of woodland into the atmosphere. In this way the plant world plays a direct part in the life processes of the earth’s organism. It is indeed a most important member of this organism, a channel through which water passes on its great circulating processes over and around the whole Earth. For this same reason it is not possible to speak of an independent circulatory system of the plant. The visible streaming of the sap in the plant is only one half of its complete circulation; the other half exists in the atmosphere or in the Earth. The plants are vascular systems through which water, the blood of the Earth, streams in living interplay with the atmosphere. Together Earth, plant world and atmosphere form a single great organism, in which water streams like living blood.”
“What is here spread out over a large space, animal and man have within themselves. What in the plant world is spread in circulation over the face of the whole Earth is in them enclosed in a small space, where it moves in the same rhythms and according to the same laws as does the water outside them in Nature.”
So in attempting to come to terms with a brain in motion, you bring into the observation window the primal relevance of water as a extraordinary special element, ‘the blood of the Earth’, in Schwenk’s terms. Out of this amorphous water, shapes and layers of patterns emerge in the gravity motion of water moving. It is those water movements spiraling into design blueprints for the life forms within the vortexing water that captivated Cousteau during his night dive with his son Falco. Water is shapes in motion-water motion’s shape is the design blueprint for Nature.