L'Iguazù nel Paranà delimita il confine tra Argentina, Brasile e Paraguay

Il Río de la Plata che sfocia nell'Oceano Atlantico. Earth Sciences and Image Analysis Laboratory, NASA Johnson Space Center, fonte: eol.jsc.nasa.gov

 

La divisione dell'Iguazù nel Paranà delimita il confine tra Argentina, Brasile e Paraguay. Il Paraná è un fiume del Sud America che attraversa il Brasile, il Paraguay e l'Argentina. In Portoghese si pronuncia Rio Paraná, in spagnolo Río Paraná, o fiume del Sud America, è il secondo fiume più lungo dell'Amazzonia, sorge in pianura nel sud del Brasile centrale e scorre generalmente fino al punto in cui, dopo un percorso di 3.032 miglia (4.880 km), si unisce al fiume Uruguay per formare il vasto Río de la Plata che sfocia nell'Oceano Atlantico. Riferimento: Encyclopædia Britannica Paranà River

The World's Most Famous Meteor Shower Picture, November 13, 1883

SAO/NASA Astrophysics Data System (ADS)

Authors: Hughes, D. W.
Journal: Earth, Moon, and Planets, Volume 68, Issue 1-3, pp. 311-322
Bibliographic Code: 1995EM&P...68..311H
Credit: Harvard.edu

The Antikythera Mechanism

The Antikythera Mechanism
Credit & License: Wikipedia

Explanation: What is it? It was found at the bottom of the sea aboard an ancient Greek ship. Its seeming complexity has prompted decades of study, although some of its functions remained unknown. X-ray images of the device have confirmed the nature of the Antikythera mechanism, and discovered several surprising functions. The Antikythera mechanism has been discovered to be a mechanical computer of an accuracy thought impossible in 80 BC, when the ship that carried it sank. Such sophisticated technology was not thought to be developed by humanity for another 1,000 years. Its wheels and gears create a portable orrery of the sky that predicted star and planet locations as well as lunar and solar eclipses. The Antikythera mechanism, shown above, is 33 centimeters high and therefore similar in size to a large book. Credit: APOD/NASA

Novaya Zemlya archipelago, Arctic Circle

Credits: ESA

This Envisat image from 19 March 2012 shows the elongated islands of the Novaya Zemlya archipelago on the left, the mainland of northwestern Russia to the right and an ice-covered Kara Sea in the centre. The Barents Sea is off the islands’ west coast. Located completely within the Arctic Circle, Novaya Zemlya is an extension of the Ural Mountains.
The Arctic’s hard environment makes it difficult to explore. Today, satellites can provide a breadth of information on polar regions such as sea-ice extent, and can facilitate navigation and communications.
This image is featured on the Earth from Space video programme

Da dove produce il calore la Terra ?

Image credit: Discovery Enterprise

Image source: www.kidsgeo.com

Questo post pubblicato su AGU - Blogosphere da Ryan Anderson, Postdoctoral fellow (Assegnista di Ricerca) presso l'U.S. Geological Survey Astrogeology Science Center alla Cornell University, intende fornire alcune delucidazioni in merito a un argomento su cui, molte persone, fanno spesso confusione: dove e come produce calore la Terra. Di solito si commettono una serie di equivoci per cui è bene fare dei chiarimenti.

Michael Mann response to Climategate

Michael E. Mann

(11/26/09): 1. "I've just completed Mike's Nature trick of adding in the real temps to each series for the last 20 years (i. e. from 1981 onwards) and from 1961 for Keith's to hide the decline." (from Phil Jones).
Phil Jones has publicly gone on record indicating that he was using the term "trick" in the sense often used by people, as in "bag of tricks", or "a trick to solving this problem ...", or "trick of the trade". In referring to our 1998 Nature article, he was pointing out simply the following: our proxy record ended in 1980 (when the proxy data set we were using terminates) so, it didn't include the warming of the past two decades. In our Nature article we therefore also showed the post-1980 instrumental data that was then available through 1995, so that the reconstruction could be viewed in the context of recent instrumental temperatures. The separate curves for the reconstructed temperature series and for the instrumental data were clearly labeled.
The reference to "hide the decline" is referring to work that I am not directly associated with, but instead work by Keith Briffa and colleagues. The "decline" refers to a well-known decline in the response of only a certain type of tree-ring data (high-latitude tree-ring density measurements collected by Briffa and colleagues) to temperatures after about 1960. In their original article in Nature in 1998, Briffa and colleagues are very clear that the post-1960 data in their tree-ring dataset should not be used in reconstructing temperatures due to a problem known as the "divergence problem" where their tree-ring data decline in their response to warming temperatures after about 1960. "Hide" was therefore a poor word choice, since the existence of this decline, and the reason not to use the post 1960 data because of it, was not only known, but was indeed the point emphasized in the original Briffa et al Nature article. There is a summary of that article available on this NOAA site:
http://www.ncdc.noaa.gov/paleo/globalwarming/briffa.html
There have been many articles since then trying to understand the reason for this problem, which applies largely to only one very specific type of proxy data (tree-ring wood density data from higher latitudes).
As for my research in this area more generally, there was a study commissioned by the National Academies of Science back in 2006 to assess the validity of paleoclimate reconstructions in general, and my own work in specific. A summary of that report, and link to it, is available here:
http://www.realclimate.org/index.php/archives/2006/06/national-academies-synthesis-report/
The New York Times (6/22/06), in an article about the report entitled "Science Panel Backs Study on Warming Climate" had the following things to say:

A controversial paper asserting that recent warming in the Northern Hemisphere was probably unrivaled for 1,000 years was endorsed today, with a few reservations, by a panel convened by the nation's preeminent scientific body...At a news conference at the headquarters of the National Academies, several members of the panel reviewing the study said they saw no sign that its authors had intentionally chosen data sets or methods to get a desired result. "I saw nothing that spoke to me of any manipulation," said one member, Peter Bloomfield, a statistics professor at North Carolina State University. He added that his impression was the study was "an honest attempt to construct a data analysis procedure."
2. "Perhaps we'll do a simple update to the Yamal post. As we all know, this isn't about truth at all, its about plausibly deniable accusations." (from me)
This refers to a particular tree-ring reconstruction of Keith Briffa's. These tree-ring data are just one of numerous tree-ring records used to reconstruct past climate. Briffa and collaborators were criticized (unfairly in the view of many of my colleagues and me) by a contrarian climate change website based on what we felt to be a misrepresentation of their work. A further discussion can be found on the site "RealClimate.org" that I co-founded and help run. It is quite clear from the context of my comments that what I was saying was that the attacks against Briffa and colleagues were not about truth but instead about making plausibly deniable accusations against him and his colleagues.
We attempted to correct the misrepresentations of Keith's work in the "RealClimate article mentioned above, and we invited him and his co-author Tim Osborn to participate actively in responding to any issues raised in the comment thread of the article which he did.
3. "Can you delete any emails you may have had with Keith re AR4? Keith will do likewise. He's not in at the moment -minor family crisis. Can you also email Gene and get him to do the same? I don't have his new email address. We will be getting Caspar to do likewise." (from Phil Jones)
This was simply an email that was sent to me, and can in no way be taken to indicate approval of, let alone compliance with, the request. I did not delete any such email correspondences.
4. "I think we have to stop considering Climate Research as a legitimate peer-reviewed journal. Perhaps we should encourage our colleagues in the climate research community to no longer submit to, or cite papers in, this journal" (from me)
This comment was in response to a very specific incident regarding a paper by Soon and Baliunas published in the journal "Climate Research". An editor of the journal, with rather contrarian views on climate change, appeared to several of us to be gaming the system to let through papers that clearly did not meet the standards of quality for the journal. The chief editor (Hans von Storch), and half of the editorial board, resigned in protest of the publication of the paper, after the publisher refused to allow von Storch the opportunity to write an editorial about how the peer review process had failed in this instance.
Please see e.g. this post at RealClimate:
http://www.realclimate.org/index.php/archives/2009/11/the-cru-hack-context/
(3rd bullet item--see the various links, which lead to letters from chief editor Von Storch, and an article by the journalist Chris Mooney about the incident).
Scientists all choose journals in which we publish and we all recommend to each other and our students which journals they should publish in. People are free to publish wherever they can and are free to recommend some journals over others. For an example of this behavior in daily life, people make choices and recommendations all the time in their purchasing habits. It is highly unusual for a chief editor and half of an editorial board to resign and that indicates a journal in turmoil that should possibly be avoided. Similarly, authors are allowed to cite any papers they want, although usually the editor will note incorrect or insufficient citing.
I support the publication of "skeptical" papers that meet the basic standards of scientific quality and merit. I myself have published scientific work that has been considered by some as representing a skeptical point of view on matters relating to climate change (for example, my work demonstrating the importance of natural oscillations of the climate on multidecadal timescales). Skepticism in the truest scientific sense of the word is good and is indeed essential to science. Skepticism should not be confused, however, with contrarianism that does not meet the basic standards of scientific inquiry.
5 "'It would be nice to try to contain the putative "MWP" (from me)
In this email, I was discussing the importance of extending paleoclimate reconstructions far enough back in time that we could determine the onset and duration of the putative "Medieval Warm Period". Since this describes an interval in time, it has to have both a beginning and end. But reconstructions that only go back 1000 years, as most reconstructions did at the time, didn't reach far enough back to isolate the beginning of this period, i.e. they are not long enough to "contain" the interval in question. In more recent work, such as the IPCC Fourth Assessment Report published in 2007, the paleoclimate reconstructions stretch nearly 2000 years back in time, which is indeed far enough back in time to "contain" or "isolate" this period in time. References: Science - Michael Mann response to Climategate

Onde atmosferiche e gravitazionali

Onde atmosferiche fotografate a bordo di un aereo. Fonte: http://www.weathervortex.com

Le onde atmosferiche vengono identificate in presenza di variazioni dell'ondulazioni atmosferiche rispetto allo stato medio di quiete dell' atmosfera. Le onde sono incluse nei parametri meteorologici, come per esempio la temperatura atmosferica, la pressione, la velocità e la direzione del vento, e coprono una vasta gamma di valori nella scala planetaria, (con lunghezze d'onda di circa 10 mila chilometri orizzontali o anche maggiori) nella mesoscala, (100-1000 km) nella piccola scala con lunghezze d'onda orizzontali di solo alcuni km, (un esempio per la meso-e la piccola scala sono le onde gravitazionali).

Faglie nell'est della California

Queste pareti, in cui si possono osservare alcune faglie, sono esposte sulla strada che porta alla Death Valley attraversando la statale che conduce alla Panamint Valley a ovest. Riferimento: American Geophysical Union - Fault

I Moeraki Boulder in Nuova Zelanda

Moeraki Boulders New Zealand

 

Karsten Sperling, http://spiff.de/photo

 

Foto di William M. Connoley

I Moeraki Boulder sono delle concrezioni formatesi lungo la spiaggia di Koekohe Beach a Otago in Nuova Zelanda a causa della cementazione del fango indurito risalente al Paleocene. Queste rocce appartengono alla Formazione Moeraki da cui, l'erosione costiera, le ha riportate in superficie.

La struttura principale dei massi ha iniziato a formarsi nel fango situato in prossimità del fondale marino. Questo è dimostrato da studi effettuati sulla loro composizione, in particolare dal contenuto di magnesio e di ferro, dagli isotopi stabili di ossigeno e di carbonio. La relativa forma sferica indica che la quantità di calcio era maggiore rispetto al contenuto di acqua.

I massi più grandi, che misurano 2 metri (6,6 piedi) di diametro, secondo una stima, hanno impiegato tra i 4,5 - 5,5 milioni di anni per aumentare di dimensione, contemporaneamente, sopra queste pietre si accumulavano dai 10 ai 50 metri (da 33 a 165 piedi) di fango. In seguito si formarono le concrezioni, le grandi crepe note come septaria. Dopodiché della calcite marrone, calcite gialla, piccole quantità di dolomite e quarzo riempirono progressivamente queste crepe quando il calo del livello del mare permise all'acqua freatica di attraversare il fango indurito che ora le avvolge.

Le rocce che si muovono nella Death Valley in California

 

 

 

 

Credit. Daniel Mayer (mav)

 

Una roccia che si muove nella Death Valley Image Credit: Nathan Alexander, Wikipedia

Come è possibile che questa roccia sia arrivata in mezzo a questo deserto ? In uno dei luoghi più insoliti sulla Terra, la Death Valley, in California, USA, si verificano dei fenomeni alquanto insoliti.

L'esopianeta Corot-7b

ESO/L. Calcada

Le misurazioni effettuate dallo strumento HARPS annunciate nel 2009 hanno stabilito che l'esopianeta Corot-7b, essendo vicino ad una Stella simile al Sole, presenta le stesse condizioni estreme della Terra ai suoi albori.

Gli scienziati non sono tutti d'accordo sull'aumento della temperatura terrestre ?

Alcuni dicono che gli scienziati non sono d'accordo sulle variazioni della temperatura terrestre. Ecco come appare il"disaccordo". Per maggiori informazioni: NASA Hearth Observatory   | NASA Climate 365 - Tumblr

Il sesso degli uccelli mesozoici suggerisce lo stile riproduttivo dei dinosauri

Confuciusornis sanctus, University of Arizona

Ricostruzione artistica del Confuciusornis sanctus di Stephanie Abramowicz del NHM Dinosaur Institute 

Confuciusornis sanctus di Alain Bénéteau

In un articolo pubblicato su Nature Communications il 22 gennaio del 2013, una squadra di paleontologi tra cui il dottor Luis Chiappe, direttore del Museo di Storia Naturale del Los Angeles County Dinosaur Institute (NHM), descrivono il sesso di una specie di uccello preistorico.

Un nuovo fossile di dinosauro modifica le teoria del volo degli uccelli

Eosinopteryx brevipenna, Credit: Julius Csotonyi



 Phylogeny of Paraves



Eosinopteryx brevipenna • Reduced plumage and flight ability of a new Jurassic paravian theropod (Theropoda: Troodontidae) from China [2013]. Credit: Royal Belgian Institute of Natural Sciences)

Il Dr Gareth Dyke, Professore associato di Paleontologia dei Vertebrati presso l'Università di Southampton, descrive su Nature Communications "Reduced plumage and flight ability of a new Jurassic paravian theropod from Chinaun", un nuovo dinosauro piumato di circa 30 cm di lunghezza, che anticipa l'esistenza di dinosauri simili a uccelli. Nel corso degli anni, i paleontologi hanno stabilito che gli uccelli si sono evoluti da un gruppo di dinosauri teropodi provenieneti dal Cretacico inferiore, circa 120-130 milioni di anni fa. Le recenti scoperte di dinosauri piumati risalenti a un periodo più antico come il Giurassico Medio e superiore hanno rafforzato questa teoria.
Il nuovo 'dinosauro uccello' Eosinopteryx brevipenna fornisce ulteriori elementi di prova in tal senso ma genera nuovi dubbi sulla teoria del famoso fossile di Archaeopteryx - ritenuto dai paleontologi come il primo uccello - un reperto fondamentale per l'evoluzione degli uccelli moderni, spiega Dyke, che lavora presso il National Oceanography Centre di Southampton.
"I nostri risultati suggeriscono che l'origine del volo è molto più complessa di quanto si pensasse in precedenza."
Il fossile rinvenuto nel nord-est della Cina indica che, nonostante fosse munito di penne, era un dinosauro incapace di volare a causa della sua ridotta apertura alare e di una struttura ossea che avrebbe limitato la sua capacità di battere le ali.
Il dinosauro aveva le dita dei piedi adatte a camminare sul terreno, poche piume nella coda e nella parte inferiore delle gambe, in modo da essere agevolato negli spostamenti terrestri. 
Oltre al Dr Dyke i co-autori dello studio sono Pascal Godefroit del Royal Institute di Scienze Naturali belga, Helena Demuynck del Earth System Science Vrije Universiteit di Brussel, Dongyu Hu dell'Istituto di Paleontologia Shenyang Normal University in Cina, un Laboratorio chiave di Ecologia della Vegetazione della Northeast Normal University in Cina, François Escuillié dell' Eldonia in Francia e Philippe Claeys del Jilin, il Museo Geologico dell'Università cinese. Riferimento: ScienceDaily - New Dinosaur Fossil Challenges Bird Flight Origins Theories. 

Il nero di carbonio è il secondo composto artificiale che contribuisce al riscaldamento globale

 Secondo la prima analisi globale quantitativa dell' impatto sul clima, il nero di carbonio (BC) è il secondo composto artificiale che contribuisce al riscaldamento globale, la sua influenza sul clima in passato è stata molto sottovalutata.

Un'intensa esplosione di raggi gamma investì la Terra nel 775 d.C.

 (Credit: NASA / Dana Berry)

Secondo una nuova ricerca condotta dagli astronomi Valeri Hambaryan e Ralph Neuhӓuser, la causa di un'intensa esplosione di radiazione ad alta energia che colpì la Terra nell'ottavo secolo, può essere attribuita a un'emissione di breve durata di raggi gamma.

The cliffs of Beachy Head

Photo Credit: Andreas-Photography

Photo Credit: S__i

Photo Credit: abridgeover

Photo Credit: TOmO

Photo Credit: abridgeover

Photo Credit: Howzey

Credit Photos: Triggerpit

 

Beachy Head is a famous natural and historic site and tourist attraction on the south coast. The cliff top area is part of the Downland Country Park managed by Eastbourne District Council.

Necrolestes patagonensis, il mammifero sudamericano sopravvissuto all'evento Kp-g

Albero filogenetico semplificato che mostra il Necrolestes come un membro appartenente al gruppo dei Meridiolestida che vissero in sudamerica.  

Necrolestes patagonensis

Un squadra internazionale di ricercatori, tra cui lo scienziato John Wible del Carnegie Museum of Natural History, hanno risolto le relazioni evolutive del Necrolestes patagonensis, il cui nome si traduce in " grande ladro", riferendosi al suo stile di vita sotteraneo di scavatore.

La Cometa del secolo, C/2012 S1 (ISON)

La Cometa ISON ripresa da Vitali Nevski ed Artyom Novichonok, i due astronomi che l'anno scoperta il 12 settembre del 2012.

La nuova cometa ISON: Unione Astrofili Italiani

The Chicxulub Debate



The Princeton model shows (at left) that the structure of the Earth's surface at the time of the meteorite impact that caused the Chicxulub crater in Mexico would have placed the Deccan Traps in India far west of the crater's antipodal point, instead of directly opposite of the impact. Correspondingly, the model shows (at right) that the meteorite struck far east of the antipodal point for the Deccan Traps, which are remnants of large volcanoes thought to have contributed to the mass extinction event at the end of the Cretaceous period. The model also revealed that the Chicxulub impact, when the Earth's surface and shape are considered, would have likely been too small to cause the Deccan Traps. Source: Princeton University

1. Chicxulub predates the KT boundary and is not the cause for the end-Cretaceous mass extinction 2. Chicxulub Crater

CHICXULUB - THE NON-SMOKING GUN

• Chicxulub Impact Predates KT Mass Extinction in NE Mexico
• Chicxulub Crater
• Conclusions - Chicxulub Impact Predates KT by 300 kyr
• Chicxulub Evidence at Brazos, Texas
• The KT Transition in Brazil
• Chicxulub Impact - No Mass Extinction
• The Great Chicxulub Debate - 2003-2004
• Reference

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The following papers can be downloaded as pdf files:

• Chicxulub impact predates K-T Boundary: new Evidence from Brazos, Texas (Gerta Keller et al., Earth and Planetary Science Letters, 255 (2007), 339-356)
• Biotic effects of impacts and volcanism (by Gerta Keller, Earth and Planetary Science Letters 215 (2003) 249-264)
  
• The end-cretaceous mass extinction in the marine realm: year 2000 assessment (by Gerta Keller, Planetary and Space Science 49 (2001) 817-830)
• Multiple impacts across the Cretaceous-Tertiary boundary (by G. Keller et al., Earth-Science Reviews 62 (2003) 327-363)
• Spherule deposits in Cretaceous-Tertiary boundary sediments in Belize and Guatemala (by G. Keller et al., Journal of the Geological Society, London, Vol. 160, 2003, pp. 783-795)
• The Non-Smoking Gun (Geological Society London)
• The Non-Smoking Gun - DEBATE (Geological Society London)
• Chicxulub impact predates the K-T boundary mass extinction (by G. Keller et al., PNAS, Vol. 101 No. 11, 2004, pp. 3753-3758.
• More evidence that the Chicxulub impact predates the K/T mass extinction (by G. Keller et al., Meteoritics & Planetary Science 39 (2004) 1127-1144)

RFERENCES: The Chicxulub Debate - Princeton University