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----------------- - 1723 - Water, Water, everywhere?
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- Astronomers are discovering water nearly everywhere they look. Water can exist as water vapor, liquid water, frozen ice, or water molecules. In fact ,water can exist in all three states, gas, liquid, solid at the same time, if pressure and temperature are just right.
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- Called the triple point on the pressure versus temperature x-y plot. Temperature / Pressure ratio = 273.16 Kelvin / 4.38 mm of mercury
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-------------------- T / P = 273.16 / 4.38
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- In Indiana where I was growing up our science was using a divining rod to find water. Farmers would walk around the farm with the rod pointing up. Then, when they were over water underground the rod would point down towards the ground. The “Y” shaped stick worked every time. When they dug the well they always found water.
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- Astronomers use spectroscopy to find water for their science. ( See Review #853 “ But a Spectrum of Light” and Review #38 “ Rainbows can tell us what the Universe is made of” ) Their science has discovered water on Jupiter’s moon Europa and on the asteroid Ceres. This signature for H2O comes from ultraviolet light that is reflected off the surfaces. This light passes through plumes, or geysers, of water vapor up to 120 miles above the surface.
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- Ceres’ water was detected in the infrared spectrum. This asteroid is orbiting between Mars and Jupiter. The water jets from the surface of the asteroid are similar to how comets create their tails.
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- A spacecraft is scheduled to arrive at the Ceres asteroid in April , 1025. We should learn much more of how Ceres is giving us this H2O “fingerprint”.
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- If astronomers find an abundance of water that will suggest that there really is not much difference between asteroids and comets.
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- But, where did all this water come from?
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- Water does not just have an H2O fingerprint. It also has a unique identity with the ratio of hydrogen to deuterium. Deuterium is an isotope of hydrogen that contains a neutron as well as a proton in the nucleus. Hydrogen has only one proton.
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- By studying the atomic structures of elements in water astronomers can determine the temperature and pressure and where it was formed. This can define time and location and environment. Water on asteroids that formed between Mars and Jupiter has a different composition than water formed in comets outside the orbit of Neptune.
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- Channels on Mars appear to have been created by running water. No liquid water exist on the surface of Mars today. Evidence shows that Mars did have rain and surface water in its distant past. Today water is frozen in the polar caps and in the top meter of surface soil.
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- Comets are ice-rich because they formed beyond the frost-line in their orbits. Comets also contain frozen carbon dioxide and carbon monoxide that are gases condensed only in the very coldest and most distant orbits in the Solar System.
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- Europa has an icy crust that likely hides a subsurface ocean of liquid water.
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- Ganymede is the largest moon in the Solar System. It has a surface of water-ice. It is thought that the large cracks and grooves in its surface are created by water erupting in the cracks, freezing, expanding , creating large craters and grooves. Some tidal heating and radioactive decay provide enough heat to liquefy the subsurface water.
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- Venus has virtually no water. Earth’s carbon dioxide is mostly in its rocks rather than in the atmosphere. If it were not the case Earth would be like Venus too hot to be inhabitable.
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- Recent studies with computer simulations are suggesting that the water was not all born in our Solar System. Maybe, more than half of the water in Earth’s oceans came form water that was in interstellar space before the Sun was even born.
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- If this were true then the water ice as well as the organic material would be equally abundant around the other stars, planets, moons. Life may be more common in many of these other solar systems. Stay tuned , there is more to learn.
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RSVP, with comments, suggestions, corrections. Index of reviews available ---
--- Some reviews are at: -------------------- http://jdetrick.blogspot.com -----
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---- www.twitter.com , --- 707-536-3272 ---- Tuesday, January 13, 2015 ---
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