Earth Has Less Water Than You Think


If you were to take all of the water on Earth — all of the fresh water, sea water, ground water, water vapor and water inside our bodies — take all of it and somehow collect it into a single, giant sphere of liquid, how big do you think it would be?

According to the U. S. Geological Survey, it would make a ball 860 miles (1,385 km) in diameter, about as wide edge-to-edge as the distance between Salt Lake City to Topeka, Kansas. That’s it. Take all the water on Earth and you’d have a blue sphere less than a third the size of the Moon.

Feeling a little thirsty?

And this takes into consideration all the Earth’s water… even the stuff humans can’t drink or directly access, like salt water, water vapor in the atmosphere and the water locked up in the ice caps. In fact, if you were to take into consideration only the fresh water on Earth (which is 2.5% of the total) you’d get a much smaller sphere… less than 100 miles (160 km) across.

Even though we think of reservoirs, lakes and rivers when we picture Earth’s fresh water supply, in reality most of it is beneath the surface — up to 2 million cubic miles (8.4 million cubic km) of Earth’s available fresh water is underground. But the vast majority of it — over 7 million cubic miles (29.2 cubic km) is in the ice sheets that cover Antarctica and Greenland.

Of course, the illustration above (made by Jack Cook at the Woods Hole Oceanographic Institution) belies the real size and mass of such a sphere of pure liquid water. The total amount of water contained within would still be quite impressive — over 332.5 million cubic miles (1,386 cubic km)! (A single cubic mile of water equals 1.1 trillion gallons.) Still, people tend to be surprised at the size of such a hypothetical sphere compared with our planet as a whole, especially when they’ve become used to the description of Earth as a “watery world”.

Makes one a little less apt to take it for granted.

Read more on the USGS site here, and check out some facts on reducing your water usage here.

Water, water, every where,
And all the boards did shrink;
Water, water, every where,
Nor any drop to drink.
– from The Rime of the Ancient Mariner, Samuel Taylor Coleridge

Enceladus On Display In Newest Images From Cassini


The latest images are in from Saturn’s very own personal paparazzi, NASA’s Cassini spacecraft, fresh from its early morning flyby of the ice-spewing moon Enceladus. And, being its last closeup for the next three years, the little moon didn’t disappoint!

The image above is a composite I made from two raw images (this one and this one) assembled to show Enceladus in its crescent-lit entirety with jets in full force. The images were rotated to orient the moon’s southern pole — where the jets originate — toward the bottom.

Cassini was between 72,090 miles (116,000 km) and 90,000 miles (140,000 km) from Enceladus when these images were acquired.

This morning’s E-19 flyby completed a trio of recent close passes by Cassini of the 318-mile (511-km) -wide moon, bringing the spacecraft as low as 46 miles (74 km) above its frozen surface. The goal of the maneuver was to gather data about Enceladus’ internal mass — particularly in the region around its southern pole, where a reservoir of liquid water is thought to reside — and also to look for “hot spots” on its surface that would give more information about its overall energy distribution.

Cassini had previously discovered that Enceladus radiates a surprising amount of heat from its surface, mostly along the “tiger stripe” features — long, deep furrows (sulcae) that gouge its southern hemisphere, they are the source of the water-ice geysers.

Cassini also used the flyby opportunity to study Enceladus’ gravitational field.

By imaging the moon with backlit lighting from the Sun the highly-reflective ice particles in the jets become visible. More direct lighting reduces the jets’ visibility in images, which must be exposed for the natural light of the scene or risk “blowing out” due to Enceladus’ natural high reflectivity.

The images below are raw spacecraft downloads right from the Cassini’s imaging headquarters in Boulder, CO.

Enceladus' geysers in action on May 2, 2012. (NASA/JPL/SSI)
Enceladus sprays ice into the hazy E ring, which orbits Saturn (NASA/JPL/SSI)

Cassini also swung closely by Dione during this morning’s flyby but the images from that encounter aren’t available yet. Stay tuned to Universe Today for more postcards from Saturn!

As always, you can follow along with the ongoing Cassini mission on JPL’s dedicated site here, as well as on the Cassini Imaging Central Laboratory for Operations (CICLOPS) site.

Playing With Water… in Space!

Expedition 30 astronaut and chemical engineer Don Pettit continues his ongoing “Science off the Sphere” series with this latest installment, in which he demonstrates some of the peculiar behaviors of thin sheets of water in microgravity. Check it out — you might be surprised how water behaves when freed from the bounds of gravity (and put under the command of a cosmic chemist!)

See more Science off the Sphere episodes here.

Were Martian Rocks Weathered by Water?


There are many ways rocks can be textured. Wind erosion, water erosion, the escape of volcanic gases during their formation (in the case of igneous rocks)… all these forces can create the pitted textures found on many rocks on Earth… and perhaps even on Mars. And according to a report published by a group of planetary geologists led by James Head of Rhode Island’s Brown University, another method may also be at play on Mars: melting snow.

Here on Earth in the hyper-arid dry valleys of Antarctica, water from melting snow erodes the surfaces of dark boulders, creating pitted textures similar to what has been found at many locations on Mars.

In order for that process to be truly analogous, though, a few conditions would have to be met on the red planet. First, the atmospheric pressure must be high enough to allow water to remain – if only temporarily – in a liquid state. Water that instantly boils away won’t have enough time to chemically attack the rock. Second, the rock itself must be at least warm enough to not freeze the water (again, must be liquid.) And third, there must actually be water, snow or frost present.

While one or more of these factors may be currently present in locations on Mars, they have not yet been found to exist all together in the same place. But that’s just what’s been found now… in Mars’ geologic past these may all have very well existed either in isolated locations or perhaps even planet-wide.

The paper’s abstract states:

For example, increases in atmospheric water vapor content (due, for example, to the loss of the south perennial polar CO2 cap) could favor the deposition of snow, which if collected on rocks heated to above the melting temperature during favorable conditions (e.g., perihelion), could cause melting and the type of locally enhanced chemical weathering that can cause pits.

In other words, if the dry ice at Mars’ south pole had melted at one point, freed-up water vapor could have fallen on rocks elsewhere as snow. If Mars were at a point in its orbit closest to the Sun and therefore experiencing warmer temperatures the snow could have then melted – especially upon darker rock surfaces.

Still, it’s possible – or even probable – that the weathering did not occur at a consistent rate across the entire surface of the rocks. Some sides may have weathered faster or slower than others, depending on how they were exposed to the elements. But if there’s one thing Mars has had a surplus of, it’s time. Even if the processes outlined in the report are indeed the cause of Mars’ pitted rocks, they have likely been in play over many hundreds of millions – even billions – of years.

Read the team’s report on the Journal of Geophysical Research here.

Thanks to Stu Atkinson for his color work on the images from Opportunity. Check out his blog The Road to Endeavour for updates on the rover’s progress.

Got Drought? Just Tow in an Iceberg


As an April Fool’s joke in 1978, Australian businessman Dick Smith claimed he was towing an iceberg from Antarctica to Sydney Harbour. He used a barge covered with white plastic and fire extinguisher foam in effort to convince those who gathered at the harbor to see it. Apparently, however, the idea is not such a joke after all. A team of engineers from France have studied the concept, did a simulation and found that icebergs floating around in the ocean could be tethered and towed to places that are experiencing a severe drought and water shortages.

The idea originally was conceived in the 1970’s by an graduate student named Georges Mougin, who even received some funds from a Saudi prince to test the idea, but not much came of it.

According to an article on PhysOrg, the French engineers looked into the idea and concluded that towing an iceberg from, for example, the waters around Newfoundland to the Canary Islands off the northwest coast of Africa, could be done, and would take just under five months when towed by a tugboat outfitted with a kite sail, traveling at about one knot.

The cost would be almost ten million dollars, however.

According to a simulated test, the iceberg would lose only 38 percent of its seven ton mass during the trip, if it was fitted with an insulated skirt.

Apparently Mougin is encouraged by the results and now at age 86 is trying to raise money for an actual iceberg-tow.

Read more details on PhysOrg.

Huge Reservoir of Water Discovered in Space 30 Billion Trillion Miles Away


From a Caltech Press Release:

Water really is everywhere. Two teams of astronomers, each led by scientists at the California Institute of Technology (Caltech), have discovered the largest and farthest reservoir of water ever detected in the universe. Looking from a distance of 30 billion trillion miles away into a quasar—one of the brightest and most violent objects in the cosmos—the researchers have found a mass of water vapor that’s at least 140 trillion times that of all the water in the world’s oceans combined, and 100,000 times more massive than the sun.

Because the quasar is so far away, its light has taken 12 billion years to reach Earth. The observations therefore reveal a time when the universe was just 1.6 billion years old. “The environment around this quasar is unique in that it’s producing this huge mass of water,” says Matt Bradford, a scientist at NASA’s Jet Propulsion Laboratory (JPL), and a visiting associate at Caltech. “It’s another demonstration that water is pervasive throughout the universe, even at the very earliest times.” Bradford leads one of two international teams of astronomers that have described their quasar findings in separate papers that have been accepted for publication in the Astrophysical Journal Letters.

Read Bradford & team’s paper here.

A quasar is powered by an enormous black hole that is steadily consuming a surrounding disk of gas and dust; as it eats, the quasar spews out huge amounts of energy. Both groups of astronomers studied a particular quasar called APM 08279+5255, which harbors a black hole 20 billion times more massive than the sun and produces as much energy as a thousand trillion suns.

Since astronomers expected water vapor to be present even in the early universe, the discovery of water is not itself a surprise, Bradford says. There’s water vapor in the Milky Way, although the total amount is 4,000 times less massive than in the quasar, as most of the Milky Way’s water is frozen in the form of ice.

Nevertheless, water vapor is an important trace gas that reveals the nature of the quasar. In this particular quasar, the water vapor is distributed around the black hole in a gaseous region spanning hundreds of light-years (a light-year is about six trillion miles), and its presence indicates that the gas is unusually warm and dense by astronomical standards. Although the gas is a chilly –53 degrees Celsius (–63 degrees Fahrenheit) and is 300 trillion times less dense than Earth’s atmosphere, it’s still five times hotter and 10 to 100 times denser than what’s typical in galaxies like the Milky Way.

The water vapor is just one of many kinds of gas that surround the quasar, and its presence indicates that the quasar is bathing the gas in both X-rays and infrared radiation. The interaction between the radiation and water vapor reveals properties of the gas and how the quasar influences it. For example, analyzing the water vapor shows how the radiation heats the rest of the gas. Furthermore, measurements of the water vapor and of other molecules, such as carbon monoxide, suggest that there is enough gas to feed the black hole until it grows to about six times its size. Whether this will happen is not clear, the astronomers say, since some of the gas may end up condensing into stars or may be ejected from the quasar.

Bradford’s team made their observations starting in 2008, using an instrument called Z-Spec at the Caltech Submillimeter Observatory (CSO), a 10-meter telescope near the summit of Mauna Kea in Hawaii. Z-Spec is an extremely sensitive spectrograph, requiring temperatures cooled to within 0.06 degrees Celsius above absolute zero. The instrument measures light in a region of the electromagnetic spectrum called the millimeter band, which lies between infrared and microwave wavelengths. The researchers’ discovery of water was possible only because Z-Spec’s spectral coverage is 10 times larger than that of previous spectrometers operating at these wavelengths. The astronomers made follow-up observations with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), an array of radio dishes in the Inyo Mountains of Southern California.

This discovery highlights the benefits of observing in the millimeter and submillimeter wavelengths, the astronomers say. The field has developed rapidly over the last two to three decades, and to reach the full potential of this line of research, the astronomers—including the study authors—are now designing CCAT, a 25-meter telescope to be built in the Atacama Desert in Chile. CCAT will allow astronomers to discover some of the earliest galaxies in the universe. By measuring the presence of water and other important trace gases, astronomers can study the composition of these primordial galaxies.

The second group, led by Dariusz Lis, senior research associate in physics at Caltech and deputy director of the CSO, used the Plateau de Bure Interferometer in the French Alps to find water. In 2010, Lis’s team was looking for traces of hydrogen fluoride in the spectrum of APM 08279+5255, but serendipitously detected a signal in the quasar’s spectrum that indicated the presence of water. The signal was at a frequency corresponding to radiation that is emitted when water transitions from a higher energy state to a lower one. While Lis’s team found just one signal at a single frequency, the wide bandwidth of Z-Spec enabled Bradford and his colleagues to discover water emission at many frequencies. These multiple water transitions allowed Bradford’s team to determine the physical characteristics of the quasar’s gas and the water’s mass.

Read Lis & team’s paper here.

What Is Water Made Of



The answer to ‘what is water made of’ is as easy as you want it to be. Do you want to just do some superficial research or do you want to look a little deeper? Superficially, pure, distilled water is composed of 2 hydrogen atoms and 1 oxygen atom. If the sample of water is not ‘pure’, the composition of the sample can be different.

Salt water obviously contains salt, but it can contain many other trace elements. Fresh water from different sources will contain different elements and minerals. These come from the rocks the water washes over and the pollutants from farms and industry. The water that you drink will contain several additives used for purification plus the fluoride that is added for our health. Rain water will have any number of pollutants that have accumulated in the atmosphere.

At high temperatures and pressures, like those in the interior of giant planets, scientists think that water exists as ionic water in which the molecules break down into a soup of hydrogen and oxygen ions, and at even higher pressures as superionic water in which the oxygen crystallizes but the hydrogen ions float around freely within the oxygen lattice.

There are many interesting facts about water. Water is a tasteless, odorless liquid. The natural color of water and ice is slightly blue, although water appears colorless in small quantities. Ice also appears colorless, and water vapor is essentially invisible as a gas. Since the water molecule is not linear and the oxygen atom has a higher electronegativity than hydrogen atoms, water carries a slight negative charge. As a result, water has a electrical dipole moment. Water can form a large number of intermolecular hydrogen bonds(four). These factors lead to to water’s high surface tension and capillary forces. Water is often referred to as the universal solvent. All major cellular components are dissolved in water. Water is at its maximum density at 3.98°C. Oddly, it becomes less dense when it is cooled down to its solid form, ice. It expands to occupy 9% greater volume in this solid state, which accounts for the fact of ice floating on liquid water.

Water covers the majority of our planet and can be found in one form or another throughout the known universe. No matter where you are on Earth, water affects you in some way each day.

We have written many articles about water for Universe Today. Here’s an article about the density of water, and here’s an article about the water on Earth.

If you’d like more info on Water, check out NASA’s Water, Water, Everywhere!. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Source: Wikipedia

Herschel Finds Water Around a Carbon Star


There’s something strange going on around the red giant star CW Leonis (a.k.a. IRC+10216). Deep within the star’s carbon-rich veil, astronomers have detected water vapor where no water should be.

CW Leonis is similar in mass to the sun, but much older and much larger. It is the nearest red giant to the sun, and in its death throes it has hidden itself in a sooty, expanding cloud of carbon-rich dust. This shroud makes CW Leonis almost invisible to the naked eye, but at some infrared wavelengths it is the brightest object in the sky.

Water was originally discovered around CW Leonis in 2001 when the Submillimeter Wave Astronomy Satellite (SWAS) found the signature of water in the chilly outer reaches of the star’s dusty envelope at a temperature of only 61 K. This water was assumed to be evidence for vaporizing comets and other icy objects around the expanding star. New observations with the SPIRE and PACS spectrometers on the Herschel Space Observatory reveal that there’s something much more surprising going on.

“Thanks to Herschel’s superb sensitivity and spectral resolution, we were able to identify more than 60 lines of water, corresponding to a whole series of energetic levels of the molecule,” explains Leen Decin from the University of Leuven and leader of the study. The newly-detected spectral lines indicate that the water vapor is not all in the cold outer envelope of the star. Some of it is much closer to the star, where temperatures reach 1000 K.

No icy fragments could exist that close to the star, so Decin and colleagues had to come up with a new explanation for the presence of the hot water vapor. Hydrogen is abundant in the envelope of gas and dust surrounding carbon stars like  CW Leonis, but the other building block of water, oxygen, is typically bound up in molecules like carbon monoxide (CO) and silicon monoxide (SiO). Ultraviolet light can split these molecules, releasing their stored oxygen, but red giant stars don’t make much UV light so it has to come from somewhere else.

An illustration of the chemical reactions caused by interstellar UV light interacting with molecules surrounding CW Leonis. ESA. Adapted from L. Decin et al. (2010)

The dusty envelopes around carbon stars are known to be clumpy, and that turns out to be the key to explaining the mysterious water vapor. The patchy structure of the shroud around CW Leonis lets UV light from interstellar space into the depths of the star’s envelope. “Well within the envelope, UV photons trigger a set of reactions that can produce the observed distribution of water, as well as other, very interesting molecules, such as ammonia (NH3),” says Decin. “This is the only mechanism that explains the full range of the water’s temperature.”

In the coming months, astronomers will test this hypothesis by using Herschel to search for evidence of water near other carbon stars.