This is the blog homepage of the Facebook group "The Earth Story" (Click here to visit our Facebook group). “The Earth Story” are group of volunteers with backgrounds throughout the Earth Sciences. We cover all Earth sciences - oceanography, climatology, geology, geophysics and much, much more. Our articles combine the latest research, stunning photography, and basic knowledge of geosciences, and are written for everyone! Winner of the award for Best Education Weblog in the 2015 bloggies
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We looked inside some of the posts by earthstory and here's what we found interesting.
Airglow over the Atacama
One of the several rising steps that climbs to the main cordillera of the Andes through the driest desert on Earth resembles a beach abutting onto a sea of clouds below and provides the backdrop for this gorgeous photo of airglow above the southern skies with our galaxy in the sky above. The ripples are caused by atmospheric waves and produce a completely different pattern to those in the skies above the Tibetan Plateau I shared once before (see http://on.fb.me/1MC62j0).
It's not just auroras that fill our sky with eerie light. The weaker phenomenon in the photo is called airglow (aka nightglow), and unlike the aurora, which is focussed towards the poles by Earth's magnetic field, it can be seen from anywhere on Earth with luck and a dark sky or long exposure photo. Both phenomena arise from excited atmospheric atoms, but with different solar sources for the excitation energy. Like aurorae, airglow can be patchy and shift on a scale of minutes across the night sky. It is also present during the day but hidden in the glare.
Aurorae are due to high speed collisions with the high energy particles in the solar wind, usually during a coronal mass ejection that is pointed towards our planet and funnelled down our world's field lines. Airglow arises from high energy components of ordinary sunlight, in this case short wave ultraviolet and X-Rays. Several mechanisms combine in the lower reaches of space to produce this glow.
Between 80 and 100 Km up from the surface, oxygen atoms get chemically excited and ionised (the electrons are stripped off from the nuclei by the energy). They then react with hydroxyl molecules (OH) to form water, or recombine into O2 and start to glow green from both chemically stimulated energy and the decay of those atoms excited by cosmic rays (just once in my life I think I've had the blue flash of Cherenkov radiation in one eye reported by astronauts). They only occur at high altitude because lower down the nitrogen in the atmosphere quenches the reaction. Other types of atom also recombine to contribute to the effect, such as nitrogen and oxygen forming nitric oxide (NO), emitting a photon of light as they do so.
It was first identified by the Swede Angstrom in 1868, and subsequent laboratory studies have shown the chemical pathways that create the light as an energetic by product of the photochemical reactions. It limits the sensitivity of ground based telescopes at visible wavelengths, and is one of the reasons space telescopes are so useful to astronomers, as they can see faint objects normally masked by airglow. It usually appears bluish green, and seems brightest about ten degrees above the horizon. Only part of the layer of air that forms our bubble glows, too high up and the atoms are too tenuous to combine, too low and their density means that the energy is dissipated by collisions rather than photochemical reactions.
While it is normally quite weak, and the photographer tells me that this picture has an unusual intensity for the phenomenon, he states that a friend obtained similar results when shooting from the same place in the same direction.
Sometime in the next couple of days, we'll put up a photo of airglow from space, so you can see the shimmering band that encircles our wonderful Blue Marble.
Image credit: Yuri Beletsky (Carnegie Las Campanas Observatory) via APOD.
"In spring 2019 gigantic walls of snow piled up along the pass road to the Timmelsjoch, Austria. Johanna Bolanos Cabrera and Jasmijn Hanegraef grabbed their longboards and took the chance to downhill through this stunning scenery. Speed is what the girls are living for!"
These yellow crystals bear testament to the forces of metamorphism, which transformed the original sea bottom limestone into glistening white marble, concentrating the impurities in the rock into gems. This particular one was magnesium rich, since the marble is dotted with red spinel crystals (magnesium aluminium oxide) along with a larger yellow-brown chunk of normbergite (hydrated fluorated magnesium silicate).
The specimen comes from the Mogok stone tract of Burma, source of the traditional pigeon's blood ruby. The original limestone was transformed from sea bottom to land and limestone to marble by the collision of India with Eurasia that eliminated the eastern half of the near gone palaeoocean Tethys (the other half is but a sad remnant called the Mediterranean as Africa removes its last vesiges).
The mineral is named after its type location from which it was first scientifically described. Unlike the 4.9 x 2.9 x 1.7 cm Burmese example in the photo which was born in what is known as a regional metamorphic event (when a large area of land is transformed in belts that reflect variations in temperature and pressure conditions during a mountain building event), the original material from Norberg in Sweden came from a different kind of metamorphism called contact metamorphism, which occurs when existing rocks surrounding an intruding mass of molten rock rising from the bowels of the Earth are baked and stewed in the igneous juices. The granites (in this case) pushed into carbonate rocks and the last refined water rich remnants of the magma gave up its fluorine as a pegmatite.
The mineral fluoresces in UV light, as electrons are excited by the higher energy and wavelength rays and give up that energy after some time, emitting lower energy visible light wavelengths as it does so. Other sources include the Franklin mines in New Jersey, Canada, Finland and Italy. As well as the colour of the specimen, crystals can also be white, orange or red. The Mohs hardness weighs in at 6.5, between feldspar and quartz.
Image credit: Rob Lavinsky/iRocks.com
"Almost three weeks of non-stop shooting, 150 Gb of videos & raw image files along with 50 GB of rendered video files to combine into this piece.
The time lapse was shot across North Pacific Ocean & East China Sea. The time lapse was taken over span of 20 days experiencing mesmerizing shades of Nature .
*Note* The narrative of the time lapse is not linear . I purposefully reshuffled some of the shots to give it a Cinematic look."
The simplest kind of fault
When rocks tear and break they can do so in a variety of ways, depending on whether they are being pulled apart (aka extension to geologists), pushed together (compression) or slid alongside each other (strike slip, like the San Andreas) by the tectonic forces affecting the area. This example is a normal fault from Iran, produced by pull apart forces, at least on a local level. The layers pick out very well the block of rock that has dropped between two others, and the two fault lines bordering it. The tectonics in Iran are complex, the main forces are compressive as Arabia separates from Africa and is in a slow motion collision that is closing the Persian Gulf. As the rock is pushed out of the way and uplifted to form mountains such as the Zagros range some regions are twisting and buckling in a rotatory motion, leading to local extensive forces and normal faulting.
River basins - commonly dominated by plant life today, but very different in Earth's Precambrian when there was no plant life at the surface to anchor rivers in place. This scientist is working on how the shape of river basins and floodplains in the plantless Precambrian differ from those seen today.
Welcome to one of my favorite hikes in Chile, Laguna Cerró castillo. It was a spectacular day hike in the northern Patagonia region of Cerro Castillo. The whole area is quite remote and we had this whole hike only to ourselves.
P.S: You can see my brother @salmansabir1559 uttering random words which makes no sense.
Slide in Bingham Canyon Mine
The Bingham Canyon mine in Utah is, by volume, the largest open pit mine in the world. It has produced a huge amount of material, most notably copper, but also silver, gold, and molybdenum – in fact, it accounts for all nearly all of those materials produced in the entire state of Utah. In 2013, the mine suffered a major collapse which interrupted production for about 3 years. On May 31, a smaller portion of the walls of that mine collapsed, as seen in these press photographs.
Some mining activities in the portion of the mine are likely to be disrupted, but the company that operates this mine has for years managed the oversteepened walls of the mine by proactively monitoring the site for motion that could indicate a developing hazard. As was the case in the large slide in 2013, all workers were evacuated from this area before the slide occurred.
Image credit: Fox 13
This is the shadow of Ingenuity, the test helicopter carried by NASA's Perseverance Mars Rover, during its first ever powered flight this morning. The helicopter did a quick test hover and landed successfully afterwards.
#Bolivia absolutely blew my mind. I’d heard of the Salt Flats before but couldn’t visualize the rest of the country. The country is so diverse, you’ve got the highest administrative capital city in the world ( #LaPaz), the largest lake in South America (#LakeTiticaca), the world’s most dangerous road (#YungasRoad), the snow capped mountains of Mik’aya, the Amazon rainforest, the largest salt flats in the world (#Uyuni) and so much more!! As an example this is the incredible #ValleDeLasAnimas - The Valley of the Souls. It’s a 30 minute drive from La Paz. Crazy to think something like this is right in the city! After the trip we were so inspired by the destination, and how little we knew of it before going, that we decided to make our first ever Beautiful Destinations Guide.
A nicely matched pair
One of the toughest jobs jewellers face is finding stones with colours to match to include them in larger pieces such as parures (gem set necklaces) or in suites of jewellery (eg a combo of ring, earrings, pendant and bracelet). Some will accumulate stones for years that fit together from many varied sources until they have enough to complete the design that they have in mind. It is also uncommon for stones from a single mine to resemble each other closely enough so these two rubies of deepest crimson hue (adding up to 45 carats) are an exceptional find.
Mined in a relatively new source of high quality ruby in Mozambique called Montepuez, from the gem belt that covered many countries during the assembly of the supercontinent Gondwana that produces most of the world's best corundum, which I call the gemlands, see http://on.fb.me/1D548m8). The deposit is large, and the most significant find in decades.
Image credit: Gemfields