Spirals: Golden or Not: Fib O’ Gnocchi?

      I attended a presentation recently that included a discussion of the Fibonacci number sequence and golden spirals. We have discussed Fibonacci numbers and golden spirals here at Partial Ellipsis of the Sun before.

        The Fibonacci number series begins as 0, 1, 1, 2, 5, 8, 13, 21, 34, 55, 89,144; each term is the sum of the previous two terms. The Golden Spiral is created using phi, the ratio of 1.6180.  In mathematics, two quantities are in the golden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities thus: 

       The illustrations in the presentation included spirals that looked like this:

      Of course, Golden Spirals look like this:

       No one else in the audience seemed bothered by equal spacing on the spiral; it drove me bonkers.  Folks commented on how beautiful the illustration was; but it was wrong!

      The Golden Spiral can be seen in the Milky Way:

And in storm patterns:

      It can also be used in image composition:

     I brought the spiral conundrum to the kindergartners who all saw immediately that the spiral had to grow so the chambered nautilus could grow, too.

      From the mouths of babes. . .

      Speaking of babes, a shout-out to my co-teacher who turned 60 on the 6th. The Babylonians considered 60 the most sacred number and a resetting of the odometer to zero in their base-60 number system. Happy sexagesimal reset, Mary!

     Does it drive you bonkers when illustrations are wrong? 

    ^^^Thanksgiving Square Chapel, Dallas, TX

Steph

Christmas Eve at Great Sand Dunes National Park and Preserve. It was an extraordinary day shared with a herd of 30 elk. See if you can find them.

Happy Sandy Holidays!

Cratonically Yours: Thinner Lithosphere and Crust in Western Antarctica Than in Eastern Antarctica

        The frozen landmass of Antarctica has been studied using satellite imagery to understand some of the  earth's tectonics, revealing  several hidden structures of the least-understood continent in research published 11/5/18.

      Due to its remote location and abundance of ice, charting the geological characteristics of Antarctica is complicated, but the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite can see what other satellites can't. GOCE precisely measured the pull of earth's gravity to map out hidden terrain.

     GOCE crashed out of orbit after running out of fuel in late 2013, but researchers are still poring over the data it collected. The researchers say it offers new insights into how Antarctica was formed, and how plate tectonics can function. See the colorful, newly-created video of continental movement.

      "In East Antarctica we see an exciting mosaic of geological features that reveal fundamental similarities and differences between the crust beneath Antarctica and other continents it was joined to until 160 million years ago," says one of the team, Dr. Fausto Ferraccioli from the British Antarctic Survey. The shape index, tectonic regularization, and crystal thickness were combined to create the above video.

      Antarctica was once part of the supercontinent Gondwana, which began to disintegrate about 130 million years ago, although the bond between Antarctica and Australia held together as recently as 55 million years ago.

      By combining GOCE readings with seismological data, the researchers were able to create 3D maps of Earth's lithosphere, made up of the crust and the molten mantle beneath. That lithosphere includes mountain ranges, ocean backs, and rocky zones or cratons, the leftovers of ancient continents embedded in continents as we know them today.

      
     "The satellite gravity data can be combined with seismological data to produce more consistent images of the crust and upper mantle in 3D, which is crucial to understand how plate tectonics and deep mantle dynamics interact," says researcher, Dr. Jörg Ebbing from Kiel University in Germany.

     The GOCE satellite circled our planet for over four years, from March 2009 to November 2013. During that time it got unusually close to Earth – an altitude of just 225 km (140 miles) – to maximize the accuracy of its measurements.


     The International Space Station, by comparison, is about two times farther away from earth's surface.

      Among the findings from the new study was the discovery of a thinner crust and lithosphere under West Antarctica compared to East Antarctica.  The latter has a mosaic of older cratons interspersed with thinner regions of rock, similar to India and Australia, to which it was once joined.

      And the data is useful for more than just tracing the remnants of ancient continents across the past 200 million years: It can be used to help figure out how ice sheets above the underlying terrain might react to warmer temperatures.

     With so many variables to consider, predicting how ice melt might progress across Antarctica is a real challenge, so any help scientists can get will be welcome. GOCE is still proving its use long after its mission ended.

Antarctically yours,
Steph

Brussels Sprouts and Heirloom Tomato Omelette

Clock this: Dandelion Seeds Have a Vortex Floating Above Their Filaments

     "Dandelion seeds fly using a method that researchers thought would not work in the real world, according to a study published on October 17, 2018, in Nature." Here is a dandelion head, also called a dandelion clock:

     "When some animals, airplanes, or seeds fly, rings of circulating air called vortices form in contact with their wings or wing-like surfaces. These vortices can help to maintain the forces that lift the animal, machine, or seed into the air. 

     Researchers thought that an unattached vortex would be too unstable to persist in nature. Yet the light, puffy seeds of dandelions use vortices that materialize just above their surfaces and lift the seed into the air.

     Dandelion seeds bear filaments that radiate out from a central stalk like the spokes on a bicycle wheel, a feature that seems to be the key to their flight. Many insects harbor such filter-like structures on their wings or legs, suggesting that the use of detached vortices for flight or swimming might be relatively common, says study co-author Dr. Naomi Nakayama, a plant scientist at the U. of Edinburgh.

      As far as vortex rings go, the dandelion's is unusual. Normally, such air bubbles stay attached to an object or totally separate and disappear. But the dandelion’s bubble separates and hangs out above the seed. “When you show it to a fluid dynamicist, it blows their mind,” says study coauthor Dr. Cathal Cummins.

     Researchers were curious about how these bristly seeds of the pappus (the seed plus the filaments) stayed in the air because they looked so different from the wing-like seeds of other plants, such as maple trees. Those structures act like the wings of a bird or airplane, generating pressure differences above and below the wing to fly. To find the answer, Dr. Nakayama and her colleagues put dandelion seeds in a vertical wind tunnel and used a laser to illuminate particles that helped to visualize the airflow around the seed.

     That’s when they saw the vortex floating above the seeds. The amount of open space between the spokes of the seeds seems to be the key to the stability of these detached vortices, says Dr. Cummins. Pressure differences between the air moving through the spokes and the air moving around the seed creates the vortex ring.

     Previous studies have found that dandelion seeds always have between 90 and 110 bristles, says Nakayama. She described it as “extremely consistent”, and that consistency turns out to be very important.

     When the team designed small silicon discs to imitate these spokes, they produced models with a range of openings: from solid discs to ones that were 92% air, like the structures on the dandelion seeds. When the researchers tested these model seeds in their wind tunnel, they found that only the discs that best approximated dandelion seeds could maintain the detached vortex.

     If the number of openings in the discs was even 10% off of those in dandelion seeds, the vortex destabilized. The seed looks inefficient for flight because it has so much open space, says Dr. Nakayama, but these openings are what allow the unattached vortex ring to remain stable."

     “It’s great to see an analysis of something we see every day but didn’t fully understand,” says Dr. Richard Bomphrey, a comparative biomechanist at the Royal Veterinary College. “To discover that there were aerodynamic mechanisms that we didn’t already know — despite the fact that we can fly things at Mach 9 — is always exciting.”

        Wow, hanging vortices in a common flower. Nature sure is dandy!
Steph

Zoë had her Peace Corps gong out service, hitting the gong thrice to represent three years of service. Proud of her and looking ahead to what she'll do next!

“Permafrost” and Thermokarst

     As temperatures rise in the arctic, “permafrost,” permanently frozen ground, is defrosting at an increased rate. 

     "However, permafrost isn't the only thing in the arctic that is disappearing. Exposed rock that was once covered in ice is dissolving, eaten away by acid. The effects of this acid bath could have far-reaching impacts on global climate, according to a new study.

     Icy permafrost is rich in minerals, which are released when the ice melts. The minerals then become vulnerable to chemical weathering, or the breakdown of rock through chemical reactions. Scientists investigated areas once covered by permafrost in the western Canadian arctic, finding evidence of weathering caused by sulfuric acid produced by sulfide minerals that were released when the permafrost melted.

     Another type of naturally occurring chemical erosion is caused by carbonic acid, and it also dissolves rock. But although carbonic-acid weathering locks carbon dioxide (CO2) in place, sulfuric-acid erosion releases CO2 into the atmosphere, and it does so in quantities that were not previously accounted for, researchers described.

      Dramatic changes are underway in the Arctic, which is warming about twice as fast as any other location on earth. Sea ice is rapidly dwindling, which reduces the ocean's heat-reflecting cover, accelerating the rise of ocean temperatures. And polar bears, which depend on sea-ice cover to hunt for seals, are losing their hunting grounds, and have a harder time finding enough to eat. 

     On land, melting permafrost is shaping new landscapes, through a process called thermokarst — a term for thawing-driven erosion that originated in Russia, according to the U.S. Geological Survey (USGS).

     Thermokarst creates land formations such as lakes, pits, and sinkholes. It was not previously known how this process could affect weathering of exposed minerals, and how that might then impact CO2 release, according to the study.

     "These processes may influence the permafrost carbon-climate feedback, but have received little attention," the researchers reported.

     Over geologic time, weathering caused by carbonic acid can help to regulate climate, by trapping CO2 and restricting its transfer into the atmosphere. But the researchers found that thermokarst in regions that were rich in sulfides drove production of sulfuric acid, rather than carbonic acid, and thereby released quantities of CO2."

      These preliminary findings were published online 9/6/18 in the journal Geophysical Research Letters. (The "Plain Language" Abstract is something I've not seen before in professional journals; have you?)

       Thermokarst--easy enough for even kindergartners to understand, eh?
Steph










 


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Forty-four More Planets Beyond Our Own Solar System: Four Have a Year of Less Than 24 Hours

    In research published today, forty-four planets outside our solar system have been unveiled at once,  dwarfing (pun intended) the usual number of confirmations from extrasolar surveys, which is typically a dozen or less. The findings may improve models of solar systems and may help researchers investigate exoplanet atmospheres. Novel techniques developed to validate the findings could hugely accelerate the confirmation of more extrasolar planet candidates.       

     Shown above are the 44 confirmed planets and their approximate size class, orbits, and surface temperatures.
(Image Credit: John Livingston).   

     The 44 validated planets are from the 10th observing campaign of the NASA K2 mission, as well as high-resolution spectroscopy and speckle imaging follow-up observations. These newly-observed planets come from an initial set of 72 vetted candidates, which researchers subjected to a validation process incorporating pixel-level analyses, light curve analyses, observational constraints, and statistical false positive probabilities.

     An international team of astronomers pooled data from U.S. space agency NASA's Kepler and the European Space Agency (ESA)'s Gaia space telescopes, as well as ground-based telescopes in the U.S. Together with Dr. John Livingston, lead author of the study and a graduate student at the University of Tokyo, the team's combined resources led to the confirmed existence of these 44 exoplanets and described various details about them.    

      A portion of the findings yield some surprising characteristics: "For example, four of the planets orbit their host stars in less than 24 hours," says Dr. Livingston (we presume)."In other words, a year on each of those planets is shorter than a day here on Earth." These contribute to a small but growing list of "ultrashort-period" planets, so it could turn out they're not as unusual as they might seem.  

  

      "It was also gratifying to verify so many small planets," continues Dr. Livingston. "Sixteen were in the same size class as Earth, one in particular turning out to be extremely small -- about the size of Venus -- which was a nice affirmation as it's close to the limit of what is possible to detect."    The source observations for this study were made by Kepler, and they would not have happened were it not for a fault in 2013, which prevented accurate control of the space telescope. "Two out of the four control-reaction wheels failed, which meant Kepler couldn't perform its original mission to stare at one specific patch of the sky," explains Dr. Motohide Tamura of the University of Tokyo. "This led to its contingent mission, 'K2' -- our observations came from campaign 10 of this mission. We're lucky Kepler continues to function as well as it does."  

      The planets observed by K2 are known as transiting planets because their orbits bring them in front of their host stars, slightly reducing their brightness. However, other astrophysical phenomena can cause similar signals, so follow-up observations and detailed statistical analyses were performed to confirm the planetary nature of these signals. As part of his doctoral work, Dr. Livingston traveled to Kitt Peak observatory in Arizona to obtain data from a special type of camera, known as a speckle interferometer installed on a large telescope there. These observations, along with follow-up observations from a telescope in Texas, were necessary to characterize the host stars and rule out false positives.

       The combination of detailed analyses of data from these ground-based telescopes, K2 and Gaia enabled the precise determination of the planets' sizes and temperatures. The team's findings include 27 additional candidates that are likely to be real planets, which will be the subject of future research.

     Scientists hope to understand what kinds of planets might be out there, but can only draw valid conclusions if there are enough planets for robust statistical analysis. The addition of a large number of new planets, therefore, leads directly to a better theoretical understanding of solar-system formation. The planets also provide good targets for detailed individual studies to yield measurements of planetary composition, interior structure and atmospheres -- in particular, the 18 planets in several multiplanet systems. "The investigation of other solar systems can help us understand how planets and even our own solar system formed," says Livingston. "The study of other worlds has much to teach us about our own.

And no, I did not planet this way,

Steph 

To honor her 25 years on the planet Earth this month, here's Zoë, and the Peace Corps Malaria Elimination Team in Ethiopia. [Zoë is third from the right.]

Ch<i>ew</i>ing Gum Art from a friend.