|
NWA 480
NWA817
NWA856
NWA1069
NWA1669
| A
small, crusted meteorite found in Algeria in November 2004 joins NWA
1195, NWA 2046 and DaG 476 as olivine-orthopyroxene-phyric
shergottites, which represent the most primitive igneous rocks known
from Mars, and may be samples from the young Tharsis volcanoes. This
latest 31.07 gram stone, purchased in Morocco by Mike Farmer and Jim
Strope, was studied by Drs. Ted Bunch and Tony Irving and their
colleagues Drs. James Wittke and Scott Kuehner at Northern Arizona
University and the University of Washington in Seattle. Like NWA 2046,
this specimen contains relatively large crystals of both olivine and
orthopyroxene which exhibit a preferred alignment as a result of
magmatic flow processes. The finer grained groundmass of the rock
consists of compositionally-zoned clinopyroxene (pigeonite and some
augite), maskelynitized plagioclase, smaller olivine grains, titanium-rich
chromite, chromite, merrillite, ilmenite, ulvöspinel and pyrrhotite.
Although this sample is similar to NWA 1195 and NWA 2046, it differs
from them in having much less extensive compositional zoning in
pyroxene and olivine. Other distinctive features are irregular patches
of late-crystallizing merrillite adjacent to groundmass pigeonite
grains and within maskelynite grains, and moat-like cavities around
maskelynite grains (which formerly may have contained soluble salts or
soft alteration assemblages of Martian origin). NWA 2626 is further
distinguished by the presence of cross-cutting veinlets and small
pockets of dark glass with quenched crystallites, which are
interpreted to have formed by shock-induced melting as this specimen
was ejected from Mars. |
METEORITICS &
PLANETARY SCIENCE
is an international monthly
journal of planetary science published by the
Meteoritical Society—a scholarly
organization promoting research and education in planetary science. First
issued in 1953, the journal publishes research articles describing the
latest results of new studies, invited reviews of major topics in
planetary science, editorials on issues of current interest in the field,
and book reviews. The publications are original, not considered for
publication elsewhere, and undergo peer-review. The topics include the
origin and history of the solar system, planets and natural satellites,
interplanetary dust and interstellar medium, lunar samples, meteors, and
meteorites, asteroids, comets, craters, and tektites. Our authors and
editors are professional scientists
representing numerous disciplines, including astronomy, astrophysics,
physics, geophysics, chemistry, isotope geochemistry, mineralogy, earth
science, geology, and biology. MAPS has subscribers in over 40 countries.
Fifty percent of MAPS' readers are based outside the USA. The journal is
available in hard copy and online
The
tangible legacy of meteoritics in the western world can be traced back
more than 500 years to the memorable year of 1492. On a bright morning in
early November of that year a stone
chondrite weighing
almost 130 kilograms abruptly ended a multimillion year journey by hitting
the Earth near the town of Ensisheim, Alsace, France, then in the hands of
Germany.
The
fall was well observed and a woodcut was made of the event, but the only
official notice was political in nature. King Maximillian of Germany just
happened to be passing through a few weeks later and used the opportunity
to declare the meteorite to be a sign of God's anger towards the French
for warring with the Holy Roman Empire.
The
remaining 55kg mass of the meteorite is on display at the Ensisheim town
hall. The earliest observed fall of a meteorite from which material still
exists is the Nogata, Japan L-chondrite that fell in A.D. 861.
The next few
hundred years were marked by the gradual advance of scientific methodology
and continuing reports of stones falling from the sky. Finally, in the
late 18th century and early 19th century the two paths converged.
The 1790s and early 1800s
experienced and unusual number of witnessed meteorite falls. In 1794 Ernst
Friedrich Chladni (klad' nee), considered the father of meteoritics,
published a book in which he concluded that stone and iron masses did fall
out of the sky and were associated with high speed fireballs. Because of
the hundreds of eyewitness reports that were coming in, many scientists
were beginning to accept these conclusions. In his book, however, Chladni
took the next great leap and concluded these objects could only come from
space. For this he was immediately ridiculed, then ignored.
Los meteoritos son pequeños
fragmentos de materia sólida que flotan por el espacio del
Sistema Solar y acaban penetrando en el campo gravitatorio de la
Tierra. Entonces caen, atravesando la
atmósfera a velocidades de hasta 70 kms. por segundo. A semejante
velocidad, el aire que tienen delante,
comprimido por las ondas de choque, se vuelve incandescente.
Este aire supercalentado calienta
a su vez las capas externas del meteorito, hasta que éste acaba por
fundirse. El aire ardiente y el material fundido producen el efecto de
"estrella fugaz" que señala la caida del meteorito. |
 |
METEORITES
|
Slide 1:
WEATHER LORE PAST CLIMATE CHANGE
Slide 2:
Is the global climate changing? Well,
it would be very odd if that was not the case. Ever since the earth’s
atmosphere first formed global climatic change has been the norm
rather than the exception.
Slide 3:
The earth has
experienced a number of colder and warmer periods throughout its
history. The cold times are the glacials or ice ages, the warmer times
are the interglacials.
Slide 4:
We are in one of the interglacials now,
but it may, in fact, be the case that the earth and its atmosphere are
generally significantly colder than it is during this present period.
|
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Slide 5: It
usual to blame we humans for changes in climate; but since we weren’t
around for the vast majority of the climate changes it follows that there
must be one or more natural causes for these fluctuations in global
temperature.
Slide 6:
Scientists have come up with several
hypotheses. Could the energy output of the sun vary? If the intensity of
solar radiation changed over time, so would the earth’s temperature. We
tend to think of the sun as an unchanging feature, in fact its energy is
often called the ‘solar constant’, but it has a known and well-recorded
short term variation in energy production, the sunspot cycle.
Slide 7:
Over an 11 year period the suns energy
waxes and wanes. Who’s to say it doesn’t have a longer and more pronounced
cycle over thousands if not millions of years?
Slide 8:
Could the orbit of the earth
around the sun change from time to time? If the earth moved further out
from the sun our share if its solar radiation would decrease and our
temperatures would fall.
Slide 9:
Yet another theory relates to mega-volcanoes,
long periods of extreme volcanic activity emitting massive amounts of dust
and gases into the upper atmosphere blocking out the radiation from the
sun. Just think how one small cloud across the sun can reduce its heat
when you’re sunbathing!
Slide 10:
Perhaps meteorite impacts may occasionally
fill the upper atmosphere with dust to create an effect similar to that
produced by volcanoes. Around 65 million years ago an impact near present
day Mexico reduced incoming solar radiation and produced a knock-on effect
that caused the world- wide extinction of species. This included the poor
dinosaur!
Slide 11:
It’s not these natural changes we really
need to worry about now, however, but the fact that for the very first
time in the history of the earth we, its occupants, are able to have a
global impact on climate. Let’s hope we don’t cause changes so devastating
that we go the same way as the dinosaur
|
Slide 1:
Asteroids Murphy McGraw
Slide 2: What they
are • Rocky and metallic objects that orbit the Sun but are too small
to be considered planets • No atmospheres • Diverse group of small
celestial bodies in the solar system • Known as "minor planets" • Made
of rock and metal
Slide 3: History •
65 million years ago • 1801 – Ceres • June 30, 1908 • Theories on
chemicals
Slide 4: Why study
them? • Where are they? Could they strike earth (again?) • Mineral
Resources • Formation of the Solar System and our own Earth.
Slide 5: How to
study them • Telescopes • Spectroscopes • Rockets • Spacecrafts • Six
space missions • Laboratory analysis of meteorites |
Slide 6:
Types • C-type • S-type • M-type • Rare types
Slide 7:
How they are classified • Classified by Aledo • Composition
derived from spectral features in their reflected sunlight • Inferred
similarities to known meteorite types
Slide 8:
Where they are located • Asteroid Belt Between the orbits
of Mars and Jupiter • Near-Earth Asteroids (NEAs) – Amors – Apollos –
Atens • Trojans
Slide 9:
Sizes and Shapes • All different shapes and sizes • Nearly
spherical (Ceres) • Very irregular (Eros, most others) • Size ranging-
very small (rocks) very large (minor planets)
Slide 10:
Bibliography / Questions? • http://nssdc.gsfc.nasa.gov/planetary/text/a
steroids.txt • http://www.nineplanets.org/asteroids.html •
http://en.wikipedia.org/wiki/Asteroid • http://dawn.jpl.nasa.gov/DawnCommunity/
flashbacks/fb_12.pdf • http://www.noao.edu/education/asteroids/
|
Here are educated
guesses about the consequences of impacts of various sizes:
| Impactor Diameter (meters) |
Yield (megatons) |
Interval (years) |
Consequences |
| < 50 |
< 10 |
< 1 |
meteors in upper atmosphere
most don't reach surface |
| 75 |
10 - 100
|
1000
|
irons make craters like Meteor
Crater; stones produce airbursts like Tunguska; land impacts
destroy area size of city |
| 160 |
100 - 1000
|
5000
|
irons,stones hit ground; comets
produce airbursts; land impacts destroy area size of large urban
area (New York, Tokyo) |
| 350 |
1000 -
10,000 |
15,000
|
land impacts destroy area size
of small state; ocean impact produces mild tsunamis |
| 700 |
10,000 -
100,000 |
63,000
|
land impacts destroy area size
of moderate state (Virginia); ocean impact makes big tsunamis |
| 1700 |
100,000 -
1,000,000 |
250,000
|
land impact raises dust with
global implication; destroys area size of large state (California,
France) |
Data from 'The Impact Hazard', by Morrison,
Chapman and Slovic, published in Hazards due to Comets and
Asteroids
|
| Of the 24,000 or
so meteorites that have been discovered on Earth, only 34 have been
identified as originating from the planet Mars |
Meteorites are classified into
three main categories:
stones, stony-irons and irons, depending on their dominant
composition. Stones are similar to common terrestrial rocks in
that their mineral composition is dominated by silicates, by far
the most prevalent rock-forming minerals on our planet. Irons are
mostly metallic in composition; they consist of alloys of iron
(Fe) and nickel (Ni), in varying proportions. Stony-irons are
combinations of both; they contain silicate and metallic phases in
approximately equal amounts.
Stones are subdivided into
two classes: chondrites and achondrites. Chondrites get their name
from the fact that they all (with some exceptions) contain
chondrules, tiny mineral spherules made mostly of silicates.
Although some may be as large as a few millimeters in diameter,
most chondrules are less than 1 mm across. In chondrites,
chondrules are bound within a consolidated and fine-grained
background matrix. Chondrites are the most primitive meteorites
known. That is, they are the most ancient ones in terms of when
their constituents came together to form a rock, and the most
unprocessed ones in terms of how little their materials have been
altered since this rock formed. Achondrites, on the other hand,
lack chondrules and represent more processed materials.
Earth's surface rocks would be achondrites were they meteorites;
they lack chondrules and are the result of extensive geological
processing (melting, for instance).
Chondrites, achondrites,
stony-irons and irons are subdivided into groups and subgroups.
These will be presented in more detail below.
Falls are meteorites whose
arrival on Earth was witnessed and recorded. Their time of fall is
thus relatively precisely known. These meteorites were usually
recovered shortly after their arrival, although often enough in
the case of showers, additional fragments from a given fall may be
recovered a long time after the fall occurred. When all falls
exclusively are considered, a reasonably good estimate of the
general population of meteorites reaching the Earth may be made.
The vast majority of falls are stones (92.8%), most of which turn
out to be chondrites (85.7% of all falls). Irons are rare (5.7% of
all falls); stony-irons rarer still (1.5%). In other words, most
meteorites falling on Earth are by far chondrites.
Finds are meteorites that
were not seen to fall but were subsequently discovered on the
ground, often long after they landed. Their arrival on Earth
(time, circumstances) is thus not well documented. The vast
majority of meteorites in museum and private collections around
the world are finds, not falls. Because stones tend to look like
ordinary terrestrial rocks, especially if they were subjected to
weathering, they are easily overlooked. Stone finds are therefore
rare in spite of the commonness of stones among falls. Meteorite
collections are instead dominated by irons, which not only have a
distinctive appearance and are therefore easier to spot, but they
resist longer than stones to weathering and are particularly
amenable to being found by metal detectors. Stony-irons would also
be common among finds if it weren't for their lesser resistance to
weathering compared to irons and, more importantly, for their
extreme rarity among falls in the first place.
Meteorites, whether falls or
finds, are usually given the name of the locality (post office, if
any) nearest the site where they were recovered. In cases where
many meteorites representing several falls are found within a
relative small area (individual blue ice fields in Antarctica for
instance), the meteorites are designated by an abbreviated
locality name (the same name for all meteorites from that area)
followed by a number giving the year of recovery and a serial
number. ALH81005, for instance, is meteorite number 5 among those
recovered in the Allan Hills area of Antarctica during the
1981-1982 field season (Note: number 5 does not necessarily mean
that this meteorite was the fifth one recovered). |
|
|
Au 19ème siècle, quand les premières expéditions Sahariennes
s'engageaient dans le désert, les risques étaient grands et les
voyages hasardeux. Aujourd'hui le GPS et la précision des cartes
satellites permettent de s'aventurer hors des pistes, dans ces
paysages marqués par l'érosion, au coeur du plus grand désert de notre
planète. Le Sahara à lui seul couvre 9 000 000 km2, s'étend sur 4800
km d'Est en Ouest et 1900 km du Nord au Sud, à travers le continent
Africain. Des températures au delà de 57° à l'ombre ont été
enregistrées. La surface du désert alterne entre des massifs dunaires
(erg), représentant 15%, des plateaux caillouteux (hammada) ou des
plaines de graviers (reg), couvrant 70%, et plusieurs massifs érodés
et profondément découpés. Cet attrait
pour le désert, nous l'avons mon frère et moi depuis de nombreuses
années, la Mauritanie, l'Algérie, le massif du Hoggar, sont des
destinations pleines de souvenirs. Aujourd'hui le car-ferry nous
emporte vers la Libye, un pays où il y a trois ans une toute petite
météorite trouvée sur une dune a éveillé notre curiosité, avant de la
transformer en une passion de tous les jours.
La traversée est l'occasion de prendre un peu de repos. Les derniers
jours avant le départ sont toujours très importants, les préparatifs
sont nombreux sur les deux véhicules 4x4 de l'expédition: vérification
de la mécanique, des équipements, des stocks de nourriture et affaires
diverses, autant de petits détails qui demain dans le désert en cas de
problème auront toute leur importance. Essayer d'éviter un maximum les
mauvaises surprises, être complètement autonome et équipé pour faire
face aux problèmes, sachant que le hasard, l'aventure et l'imprévu
nous rattraperons bien assez tôt, eux aussi sont du voyage! |
|
Welcome to the Michael Farmer Collection of Meteorites |
 |
Les
météorites, mystérieuses " pierres noires tombées du ciel ", sont peut
être à l'origine de la vie sur Terre... |
Pour plus
d'information sur la chimie et la pétrologie des météorites
cliquez ici
si vous voulez acheter ou échanger des météorites
cliquez ici |
Un meteoro es lo que se conoce de
manera común como "estrella fugaz" (estela brillante que atraviesa
el cielo), mientras que el objeto que cae en llamas se le denomina
bólido o meteoroide . Muchos bólidos
pequeños, que penetran en la atmósfera casi verticalmente y a gran
velocidad, o que están compuestos de material fragmentable, se funden,
vaporizan y desintegran durante el descenso, y no llegan a caer en
tierra.
En términos estrictos, sólo se le
da el nombre de meteoritos a los bólidos que no se queman por
completo en la atmósfera y consiguen llegar al suelo. Algunos lo
logran gracias a su enorme tamaño inicial, que les permite conservar
algo de materia sin fundir antes de caer en tierra. Otros, sobre todo
los metálicos, porque son sumamente resistentes; otros, porque
penetran en la atmósfera en una trayectoria muy oblicua que les hace
perder velocidad poco a poco, sin calentarse demasiado. Esta es la
misma técnica que emplean las lanzaderas espaciales para regresar a
salvo a la Tierra.
La Tierra está sometida a un
constante bombardeo de meteoritos y meteoroides. Se ha calculado que
cada año llega a nuestra atmósfera más de 20.000 toneladas de material
del espacio.
¿De dónde proceden estos objetos?
La mayoría de las respuestas tienden a considerarlo residuos de las
primmeras etapas de formación del
Sistema Solar, ya que la mayoría de los meteoritos contienen cristales
minerales que, según los datos
científicos, cuando los granos de polvo interestelar de la nube -o
nebulosa- de la que surgirá el Sistema
Solar se condensaron en pequeños cuerpos denominados planetesimales.
|
 |
Hola y recepción a Arizona Skies Meteorites.
Compramos meteoritos. Si encuentra un meteorito contactarnos ahora.
¡Pagamos los mejores precios meteoritos!
|
Meteorites have been used and worshipped by various societies for
thousands of years. The Willamette
octahedrite of
Oregon, U.S.A., the Campo del Cielo octahedrite of Argentina and the
Cape York octahedrites of western Greenland were worked by indigenous
natives as a source of iron for tools and jewelry for hundreds, if not
thousands, of years before being discovered by Europeans. The Phrygian
stone, witnessed to fall in 2000 BC, was worshipped by ancient Romans
for hundreds of years and meteorites have been found in Egyptian tombs.
Many
early cultures recognized certain stones as having fallen from the sky
whether as a result of an oral history of the fall or as an attempt to
reconcile the unusual nature of a rock of pure metal. But to the
scientists of the Renaissance and later periods, stones falling from the
heavens were considered superstition at best, heresy at worst.
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