Monthly Archives: February 2016
meteorites hidden just under the Antarctic ice.
the surface in Antarctica, but compared to elsewhere on Earth, few of them are
made of iron.
missing metallic rocks might be burying themselves, by melting the ice as
sunlight heats them.
should be there. We just have to go and locate them,” said Dr Katherine
Joy from the University of Manchester, a co-author of the paper published in
hunting ground, because the rocks are collected from their landing sites by
glacial flows and transported to concentrated dumping-grounds.
ice, and then the ice progressively moves away from the plateau. And where it
hits these barriers, along the Transantarctic Mountains, the ice gets moved
up,” Dr Joy told the BBC.
meteorites from the interior fall sites to the ‘meteorite stranding zones’ for
the past couple of million years or so.”
|Iron meteorites. By Waifer X (originally posted to Flickr as 090423-1080887) [CC BY 2.0 (http://ift.tt/o655VX)%5D, via Wikimedia Commons|
that iron-rich meteorites – whether partly or wholly made of the metal – are
surprisingly scarce, compared to the percentage collected in other places
around the world.
one made of iron and the other rocky and non-metallic, inside blocks of ice. A special
lamp was trained on the ice from above, to mimic the rays of the Sun.
downward through the ice block. But because the metal conducts heat more
efficiently, the iron meteorite sank further, faster.
mathematical simulation. Their model showed that this Sun-driven burrowing
would be enough to cause iron-rich rocks to sink so much during the long summer
days that, over the course of the year, it would account fairly precisely for
the lack of iron space rocks welling their way to the surface of the Antarctic
They’re forever trapped, 50-100cm or so below the ice,” Dr Joy explained.
the hunt is on.
“The challenge is now set – to be the first team to locate this reserve of
meteorites and retrieve samples from it.”
handful – so far – have been pulled out from beneath the ice. This is mostly
for practical reasons, Dr Joy said.
controlled way is difficult enough with things sitting on the surface. To
access ones that are subsurface – nobody’s really tried to do that so
metal detectors might help target the search. And the potential rewards are
the Solar System,” Dr Joy said.
planet clumped together; others – like iron and rocky-iron meteorites – offer
clues from a more intermediate stage, when baby planets with cores, mantles and
crusts were trying to form.
the cores and the internal structures of different planetesimals.
planets, that formed in the solar system but never really got big enough and
were broken up in collision events.”
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|Rising sea levels will threaten residents of many countries, say researchers.|
Too much of the climate change policy debate has focused on observations of the past 150 years and their impact on global warming and sea level rise by the end of this century, the authors say. Instead, policy-makers and the public should also be considering the longer-term impacts of climate change.
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element 111, a team of German scientists led by Peter Armbruster at the
Gesellschaft für schwerionenforschung (GSI) facility at Darmstadt, Germany,
claimed to have created an atom of the element 112. Its nucleus has 112 protons
and 166 neutrons, giving it a mass number of 277. As a new element it was named
ununbium, symbol Uub, according to an internationally adopted system for naming
new elements. This was based on the presence of one atom of the element made by
accelerating zinc atoms to high speed and bombarding them into lead. When an
atom of each fused to make the new nucleus, it lasted a fraction of a
thousandth of a second before decaying, emitting an alpha particle to become a
nucleus of element 110.
the same number of protons in their atomic nuclei (i.e. the same atomic number,
Z). There are 118 elements that have been identified, of which the first 94
occur naturally on Earth with the remaining 24 being synthetic elements. There
are 80 elements that have at least one stable isotope and 38 that have
exclusively radioactive isotopes, which decay over time into other elements.
Iron is the most abundant element (by mass) making up the Earth, while oxygen
is the most common element in the crust of the earth.
|The Periodic Table, by Sandbh (Own work) via Wikimedia Commons|
the universe. However astronomical observations suggest that ordinary
observable matter is only approximately 15% of the matter in the universe: the
remainder is dark matter, the composition of which is unknown, but it is not
composed of chemical elements. The two lightest elements, hydrogen and helium
were mostly formed in the Big Bang and are the most common elements in the
universe. The next three elements (lithium, beryllium and boron) were formed
mostly by cosmic ray spallation, and are thus more rare than those that follow.
Formation of elements with from six to twenty six protons occurred and
continues to occur in main sequence stars via stellar nucleosynthesis. The high
abundance of oxygen, silicon, and iron on Earth reflects their common
production in such stars. Elements with greater than twenty-six protons are
formed by supernova nucleosynthesis in supernovae, which, when they explode,
blast these elements far into space as planetary nebulae, where they may become
incorporated into planets when they are formed.
with a given number of protons (regardless of whether they are or they are not
ionized or chemically bonded, e.g. hydrogen in water) as well as for a pure
chemical substance consisting of a single element (e.g. hydrogen gas).
atoms held together by chemical bonds, they form chemical compounds. Only a
minority of elements are found uncombined as relatively pure minerals. Among
the more common of such “native elements” are copper, silver, gold,
carbon (as coal, graphite, or diamonds), and sulphur. All but a few of the most
inert elements, such as noble gases and noble metals, are usually found on
Earth in chemically combined form, as chemical compounds. While about 32 of the
chemical elements occur on Earth in native uncombined forms, most of these
occur as mixtures. For example, atmospheric air is primarily a mixture of
nitrogen, oxygen, and argon, and native solid elements occur in alloys, such as
that of iron and nickel.
with primitive human societies that found native elements like carbon, sulphur,
copper and gold. Later civilizations extracted elemental copper, tin, lead and
iron from their ores by smelting, using charcoal. Alchemists and chemists
subsequently identified many more, with almost all of the naturally-occurring
elements becoming known by 1900.
the periodic table, which organizes the elements by increasing atomic number
into rows (“periods”) in which the columns (“groups”) share
recurring (“periodic”) physical and chemical properties. Save for
unstable radioactive elements with short half-lives, all of the elements are
available industrially, most of them in high degrees of purity.
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the early Earth and a “planetary embryo” called Theia approximately
100 million years after the Earth formed, UCLA geochemists and colleagues
which occurred almost 4.5 billion years ago, but many thought the Earth
collided with Theia (pronounced THAY-eh) at an angle of 45 degrees or more — a
powerful side-swipe (simulated in this 2012 YouTube video). New evidence
reported Jan. 29 in the journal Science substantially strengthens the case for
a head-on assault.
from the moon by the Apollo 12, 15 and 17 missions, as well as six volcanic
rocks from the Earth’s mantle – five from Hawaii and one from Arizona.
|By Gregory H. Revera (Own work) [CC BY-SA 3.0 (http://ift.tt/HKkdTz) or GFDL (http://ift.tt/KbUOlc)%5D, via Wikimedia Commons|
signature revealed in the rocks’ oxygen atoms. (Oxygen makes up 90 percent of
rocks’ volume and 50 percent of their weight.) More than 99.9 percent of
Earth’s oxygen is O-16, so called because each atom contains eight protons and
eight neutrons. But there also are small quantities of heavier oxygen isotopes:
O-17, which have one extra neutron, and O-18, which have two extra neutrons.
Earth, Mars and other planetary bodies in our solar system each has a unique
ratio of O-17 to O-16 – each one a distinctive “fingerprint.”
that the moon also has its own unique ratio of oxygen isotopes, different from
Earth’s. The new research finds that is not the case.
the moon’s oxygen isotopes; they’re indistinguishable,” said Edward Young,
lead author of the new study and a UCLA professor of geochemistry and
techniques to make extraordinarily precise and careful measurements, and
verified them with UCLA’s new mass spectrometer.
share chemical signatures was very telling, Young said. Had Earth and Theia
collided in a glancing side blow, the vast majority of the moon would have been
made mainly of Theia, and the Earth and moon should have different oxygen
isotopes. A head-on collision, however, likely would have resulted in similar
chemical composition of both Earth and the moon.
moon, and evenly dispersed between them,” Young said. “This explains
why we don’t see a different signature of Theia in the moon versus the
now makes up large parts of Earth and the moon) was growing and probably would
have become a planet if the crash had not occurred, Young said. Young and some
other scientists believe the planet was approximately the same size as the
Earth; others believe it was smaller, perhaps more similar in size to Mars.
Theia removed any water that the early Earth may have contained. After the
collision – perhaps tens of millions of year later – small asteroids likely
hit the Earth, including ones that may have been rich in water, Young said.
Collisions of growing bodies occurred very frequently back then, he said,
although Mars avoided large collisions.
professor at UC Davis; and, separately during the same year by Robin Canup of
the Southwest Research Institute.
researcher in Young’s laboratory; Paul Warren, a researcher in the UCLA
department of Earth, planetary, and space sciences; David Rubie, a research
professor at Germany’s Bayerisches Geoinstitut, University of Bayreuth; and
Seth Jacobson and Alessandro Morbidelli, planetary scientists at France’s
Laboratoire Lagrange, Université de Nice.
and a European Research Council advanced grant (ACCRETE).
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