VISIT WEBSITE >>>>> http://gg.gg/y83ws?3428345 <<<<<<
The force of the explosion was powerful enough to knock over trees in a region hundreds of miles wide. Scientists think the meteor itself was about feet 37 meters across and weighed million pounds million kilograms.
Locally, hundreds of reindeer were killed, but there was no direct evidence that any person perished in the blast. More recently, in the world was startled by a brilliant fireball that streaked across the sky above Chelyabinsk, Russia.
The house-sized meteoroid entered the atmosphere at over 11 miles 18 kilometers per second and blew apart 14 miles 23 kilometers above the ground. The explosion released the energy equivalent of around , tons of TNT and generated a shock wave that blew out windows over square miles square kilometers and damaged buildings.
More than 1, people were injured in the blast, mostly due to broken glass. The smaller piece in the foreground is called "Lebanon B. Meteor Crater in Arizona. Note vehicles in parking lot for scale. Credit: USGS. Full Moon Guide: October - November Models and lab tests suggest the asteroid could be venting sodium vapor as it orbits close to the Sun, explaining its increase in brightness. The Perseids are already showing up in our night skies, and they peak in mid-August.
The Perseids are on the Rise! The next full Moon will be on Thursday afternoon, Oct. The Moon will appear full from Wednesday morning through Saturday morning. Despite its small size, this space rock is a colossal find.
It's one of the best-preserved meteorites of its kind ever found. Ice-blue clouds are drifting over the Arctic and that means noctilucent cloud season is here. Australian Meteor Crater is the Oldest Known. What's Up for January? Morning meteors, Mars meets its "rival," and the Moon comes around for another visit with Venus.
What's Up for January Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Meteorites are the last stage in the existence of these type of space rocks. Before they were meteorites, the rocks were meteor s. Before they were meteors, they were meteoroid s.
Meteoroids are lumps of rock or metal that orbit the sun. Some meteorites, however, are as large as boulder s. The largest meteorite found on Earth is the Hoba meteorite discover ed in Namibia in The Hoba meteorite weighs roughly 54, kilograms , pounds. The Hoba meteorite is so big, and so heavy, it has never been moved from where it was found! Most meteorites look very much like rocks found on Earth, except meteorites usually have a dark, burned exterior.
This exterior is formed as friction from the atmosphere melts the meteorite as it crashes toward Earth. Known as thermal ablation , this process can also give meteorites a roughened, smooth, or thumbprint surface.
Thermal ablation creates these different texture s due to different chemicals present in the meteorite. Meteorites crash through the atmospheres of all planet s and moon s in our solar system. Some planets and moons don't have enough atmosphere to break apart meteors, resulting in large meteorites. These larger meteorites create deep, round impact crater s that can be found all over our Moon, Mercury, and Mars.
More than 60, meteorites have been found on Earth. Scientists have divided these meteorites into three main types: stony, iron, and stony-iron. Each of these types has many sub-groups. Stony meteorite s are made up of mineral s that contain silicate s—material made of silicon and oxygen. They also contain some metal—nickel and iron. There are two major types of stony meteorites: chondrites and achondrites.
Chondrite s themselves are classified into two major groups: ordinary and carbonaceous. Ordinary chondrites are the most common type of stony meteorite, accounting for 86 percent of all meteorites that have fallen to Earth. They are named for the hardened droplets of lava , called chondrule s, embed ded in them. Chondrites formed from the dust and small particle s that came together to form asteroid s in the early solar system, more than 4.
Ordinary chondrites can be classified into three main groups. The H chondrite group has a h igh amount of iron. The L chondrite group has a l ow amount of iron. The LL group has a l ow amount of iron and a l ow amount of metal in general. Carbonaceous chondrite s are much more rare than ordinary chondrites. Astronomer s think carbonaceous chondrites formed far away from the sun as the early solar system developed.
In later years, however, it became clear that the necessary catalysts were created on the meteorite parent body and were not present in the solar nebula Kerridge Also, the carbon isotopic compositions of meteoritic organic compounds were not consistent with a Fischer-Tropsch scenario; carbon monoxide, the proposed starting material for the Fischer-Tropsch reaction, contained more 12 C than the hydrocarbons in Murchison, not more 13 C as would be expected Yuen Moreover, the carbon isotopic measurements of individual normal alkanes reveal terrestrial values that are distinct from the majority of meteoritic organic matter Sephton b.
It appears, therefore, that normal alkanes in meteorites do not originate from Fischer-Tropsch reactions in the solar nebula but are simply contributions from our terrestrial environment once the meteorite has fallen to Earth. In chondrites, organic matter is present within the fine-grained inorganic meteorite matrix figure 1e which contains evidence of alteration by liquid water on the parent asteroid.
Hence, a general relationship between extraterrestrial organic matter and inorganic aqueous alteration products in carbonaceous chondrites has been recognized for some time. Recently, however, it has been discovered that the association is highly specific to a particular inorganic phase — clay minerals Pearson The discovery is enormously significant as clays are unique as mineral partners for prebiotic organic synthesis due to their ability to adsorb organic molecules and catalyse mutual reactions.
Clay minerals, therefore, may have trapped and concentrated organic matter in the early solar system and organic—inorganic interactions may have played a role in the assembly of increasingly complex organic entities 4. The recognition of clay mineral—organic matter relationships in ancient extraterrestrial samples has a bearing on the possible ubiquity of life in the early solar system. Chondritic material would have been a common component of the inner solar system shortly after its formation.
Thus, the biologically useful products of clay mineral—organic matter interactions would have also been widespread, and delivered to planetary surfaces through the accretion of carbonaceous asteroids.
Life, therefore, may have originated on planets other than the early Earth, if suitable conditions were available, even temporarily. With the recognition that meteorites contain many biologically useful molecules it is enlightening to consider that extraterrestrial objects can deliver considerable amounts of organic matter to the Earthk's surface. Even if only a small fraction of the molecules delivered during impact prove biologically relevant they would have had a significant impact on the prebiotic chemistry of the Earth.
It was suggested that extraterrestrial objects may have seeded the early Earth with an extensive list of ingredients for the recipe of life. Modern theories imply that the early Earth had a non-reducing atmosphere composed mainly of carbon dioxide and nitrogen in which the in-situ generation of organic matter would be rather sluggish and inefficient.
Under such conditions the supply of extraterrestrial organic matter to the Earth's surface would have been an important source of life's organic starting materials. Large disparities do exist between the molecular inventories of meteorites and life. For instance, the abundances of compound classes are very different; meteoritic organic matter contains greater amounts of aromatic organic matter Sephton However, as the recently detected association between clay minerals and organic matter illustrates, opportunities would have existed in the early solar system to selectively concentrate the more biologically useful molecules such as amino acids and carboxylic acids.
In addition, the complexity of molecules in life is far greater than that seen in meteorites. Murchison may contain some of the monomers but does not host more complex polymers used in living systems. For the meteoritic units to begin to resemble life, the monomers must be strung together in some way to form bigger more complex chemical structures. It is clear that on the early Earth significant hurdles must have been overcome if meteoritic organic matter was transformed into primitive life.
Yet these obstacles would be the same as those faced by any developing organic system irrespective of the source of starting material. With this in mind it is useful to recall the chirality of amino acids. The slight L-excess in meteoritic amino acids is thought to be an abiotic pre-solar feature while life on Earth contains the L form of amino acids exclusively.
If this is more than just coincidence, then it seems that the molecular preferences of Earth's organisms do in fact originate from environments external to the Earth. Carbonaceous chondrites provide an insight into the organic chemistry of the early solar system and the rich organic inventory in these objects is a record of the first chemical steps towards life, frozen in time.
Although much has been learned already, the carbonaceous chondrites remain an information source with much to reveal. Improving analytical techniques are detecting smaller amounts of fascinating substances and new materials for study are becoming available as fresh meteorites, such as the Tagish Lake meteorite which fell in , continue to arrive at the Earth's surface. In the future, scientists will not have to wait passively for the arrival of such materials because sample return missions to asteroids are already underway.
It appears inevitable that further glimpses of our cosmic beginnings will follow in the years ahead. Google Scholar. Google Preview. Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide. Sign In or Create an Account. Sign In. Advanced Search. Search Menu. Article Navigation. Close mobile search navigation Article Navigation. Volume Article Contents Abstract. Types of organic matter in meteorites.
Free compounds. Calcium salt. Short aliphatic molecules. Sulphur compounds. Macromolecular materials. Stable isotopes — a pre-solar record. Stone meteorites that contain these chondrules are known as "chondrites. Space rocks without chondrites are known as "achondrites.
Achondrites contain little or no extraterrestrial iron, making them much more difficult to find than most other meteorites, though specimens often display a remarkable glossy fusion crust which looks almost like enamel paint.
Stony-Iron Meteorite: A sea of gold and orange olivine crystals the gemstone peridot lie suspended in a matrix of extraterrestrial iron-nickel in this polished slice of the Imilac pallasite, first discovered in Chile's remote Atacama Desert in When properly prepared, pallasites are among the most alluring of meteorite, and are highly prized by collectors, both because of their rarity and beauty.
Do we really find lunar and martian rocks on the surface of our own planet? The answer is yes, but they are extremely rare. About one hundred different lunar meteorites lunaites and approximately thirty Martian meteorites SNCs have been discovered on earth, and they all belong to the achondrite group. Impacts on the lunar and Martian surfaces by other meteorites fired fragments into space and some of those fragments eventually fell on earth. Stony-Iron Meteorite: The mesosiderite Vaca Muerta shows characteristics of both iron and stone meteorites, hence its class—a stony-iron.
This weathered fragment was found in Chile's Atacama Desert. One face has been cut and polished to reveal a mottled black and silver interior. They are comprised of roughly equal amounts of nickel-iron and stone and are divided into two groups: pallasites and mesosiderites. Pallasites are perhaps the most alluring of all meteorites, and certainly of great interest to private collectors.
Pallasites consist of a nickel-iron matrix packed with olivine crystals. When olivine crystals are of sufficient purity, and display an emerald-green color, they are known as the gemstone peridot.
Pallasites take their name from a German zoologist and explorer, Peter Pallas, who described the Russian meteorite Krasnojarsk, found near the Siberian capital of the same name in the 18th Century. When cut and polished into thin slabs, the crystals in pallasites become translucent giving them a remarkable otherworldly beauty. The mesosiderites are the smaller of the two stony-iron groups. They contain both nickel-iron and silicates and usually show an attractive, high-contrast silver and black matrix when cut and polished-the seemingly random mixture of inclusions leading to some very striking features.
The word mesosiderite is derived from the Greek for "half" and "iron," and they are very rare. Of the thousands of officially cataloged meteorites, fewer than one hundred are mesosiderites.
Comments