Massive ocean discovered towards Earths core - 12 June 2014 by Andy Coghlan + Two giant Planets may cruise unseen beyond Pluto. (Posted @New Scientist, compiled by Rique Seraphico). Source Text Link: newscientist/article/dn25723-massive-ocean-discovered-towards-earths-core.html#.U5vNdpRdXni 12 June 2014 by Andy Coghlan, A reservoir of water three times the volume of all the oceans has been discovered deep beneath the Earths surface. The finding could help explain where Earths seas came from. The water is hidden inside a blue rock called ringwoodite that lies 700 kilometres underground in the mantle, the layer of hot rock between Earths surface and its core. The huge size of the reservoir throws new light on the origin of Earths water. Some geologists think water arrived in comets as they struck the planet, but the new discovery supports an alternative idea that the oceans gradually oozed out of the interior of the early Earth. Its good evidence the Earths water came from within, says Steven Jacobsen of Northwestern University in Evanston, Illinois. The hidden water could also act as a buffer for the oceans on the surface, explaining why they have stayed the same size for millions of years. Pinging the Planet: Jacobsens team used 2000 seismometers to study the seismic waves generated by more than 500 earthquakes. These waves move throughout Earths interior, including the core, and can be detected at the surface. They make the Earth ring like a bell for days afterwards, says Jacobsen. By measuring the speed of the waves at different depths, the team could figure out which types of rocks the waves were passing through. The water layer revealed itself because the waves slowed down, as it takes them longer to get through soggy rock than dry rock. Jacobsen worked out in advance what would happen to the waves if water-containing ringwoodite was present. He grew ringwoodite in his lab, and exposed samples of it to massive pressures and temperatures matching those at 700 kilometres down. Sure enough, they found signs of wet ringwoodite in the transition zone 700 kilometres down, which divides the upper and lower regions of the mantle. At that depth, the pressures and temperatures are just right to squeeze the water out of the ringwoodite. Its rock with water along the boundaries between the grains, almost as if theyre sweating, says Jacobsen. Damp down there: Jacobsens finding supports a recent study by Graham Pearson of the University of Alberta in Edmonton, Canada. Pearson studied a diamond from the transition zone that had been carried to the surface in a volcano, and found that it contained water-bearing ringwoodite, the first strong evidence that there was lots of water in the transition zone (Nature, doi.org/s6h). Since our initial report of hydrous ringwoodite, weve found another ringwoodite crystal, also containing water, so the evidence is now very strong, says Pearson. So far, Jacobsen only has evidence that the watery rock sits beneath the US. He now wants to find out if it wraps around the entire planet. We should be grateful for this deep reservoir, says Jacobsen. If it wasnt there, it would be on the surface of the Earth, and mountain tops would be the only land poking out. Journal reference: Science, DOI: 10.1126/science.1253358 _______________________________________________ Two giant planets may cruise unseen beyond Pluto. Text Link: newscientist/article/dn25711-two-giant-planets-may-cruise-unseen-beyond-pluto.html#.U5vPHpRdXng 11 June 2014 by Nicola Jenner, For similar stories, visit the Solar System Topic Guide. The monsters are multiplying. Just months after astronomers announced hints of a giant Planet X lurking beyond Pluto, a team in Spain says there may actually be two supersized planets hiding in the outer reaches of our solar system. When potential dwarf planet 2012 VP113 was discovered in March, it joined a handful of unusual rocky objects known to reside beyond the orbit of Pluto. These small objects have curiously aligned orbits, which hints that an unseen planet even further out is influencing their behaviour. Scientists calculated that this world would be about 10 times the mass of Earth and would orbit at roughly 250 times Earths distance from the sun. Now Carlos and Raul de la Fuente Marcos at the Complutense University of Madrid in Spain have taken another look at these distant bodies. As well as confirming their bizarre orbital alignment, the pair found additional puzzling patterns. Small groups of the objects have very similar orbital paths. Because they are not massive enough to be tugging on each other, the researchers think the objects are being shepherded by a larger object in a pattern known as orbital resonance. Planet Shepherd: For instance, we know that Neptune and Pluto are in orbital resonance – for every two orbits Pluto makes around the sun, Neptune makes three. Similarly, one group of small objects seems to be in lockstep with a much more distant, unseen planet. That world would have a mass between that of Mars and Saturn and would sit about 200 times Earths distance from the Sun. Some of the smaller objects have very elongated orbits that would take them out to this distance. It is unusual for a large planet to orbit so close to other bodies unless it is dynamically tied to something else, so the researchers suggest that the large planet is itself in resonance with a more massive world at about 250 times the Earth-sun distance – just like the one predicted in the previous work. Observing these putative planets will be tricky. The smaller bodies are on very elliptical orbits and were only spotted when they ventured closest to the sun. But the big planets would have roughly circular orbits and would be slow moving and dim, making them tough for current telescopes to see. Its not at all surprising that they havent been found yet, says Carlos. As there are only a few of these extremely distant objects known, its hard to say anything definitive about the number or location of any distant planets, says Scott Sheppard at the Carnegie Institution for Science in Washington DC, one of the discoverers of 2012 VP113. However, in the near future we should have more objects to work with to help us determine the structure of the outer solar system. Reference: arxiv.org/abs/1406.0715
Posted on: Sat, 14 Jun 2014 04:32:35 +0000
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