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sâmbătă, 4 august 2012

Alvarado And Tenochtitlan

While Hernan Cortes is known as the primary conqueror of the Aztec people and Mexico, he didn't do it alone. History has also shed light on his second in command, Pedro de Alvarado. 

This military strategist, later to be named Governor of Guatemala, became infamous for his role in the dramatic fall of Tenochtitlan and the ensuing battles for supremacy and survival.

Satellites watch stellar death throes

Astronomers think they have seen the flare of a dying star being eviscerated by a black hole. The signal, spotted by three different satellites, could shed light on the relationship between the smaller black holes seen in our own galaxy and the supermassive ones in distant reaches of the Universe.

The stellar victim was first seen1 in 2011 by Swift, a NASA satellite designed to spot bursts of high-energy photons known as γ-rays. For more than a month, Swift watched a signal from a distant galaxy, which eventually faded from view. Subsequent analysis showed that the γ-rays probably came from a star being ripped to pieces by a previously unknown black hole (see 'The awakening of a cosmic monster').

Arsenic eyes rice nutrients

ARSENIC accumulation in rice is something that is largely unexplored. A study has now found that the heavy metal can disrupt amino acid synthesis in the grain, a staple diet for many. This can reduce the levels of essential and non-essential amino acids found mainly in rice which are essential for a healthy life.

Essential amino acids like lysine, phenylealanine, histidine and methionine not only improve digestion, stimulate hormonal release and enhance memory, they are also the building blocks of all proteins. Deficiency of glutamic acid, a non-essential amino acid, has been linked to Parkinson’s disease.

Grupul Local

Galaxia noastra, Calea Lactee, este membra a unui grup din apropiere care este compus din aproximativ 40 de galaxii cunoscute, numit Grupul Local. Numarul real ramane necunoscut, intrucat recensamantul a crescut in mod constant de-a lungul anilor, pe masura ce noi membri au fost identificati. Grupul Local contine galaxii de aproape toate tipurile, inclusiv galaxii spirala ca M31, M33 si, desigur, Calea Lactee. Acesta contine dec asemenea cateva galaxii neregulate luminoase (norii lui Magellan), cateva galaxii neregulate slab iluminate, galaxii pitice (nucleate, sferoidale, eliptice si de tip compact). Singurul tip important de galaxie care nu este reprezentat in Grupul Local este tipul eliptic.

Gale Crater: Geological 'sweet shop' awaits Mars rover

John Grotzinger is the project scientist on Nasa's latest multi-billion-dollar mission to Mars.

He's going to become a familiar face in the coming months as he explains to TV audiences the importance of the discoveries that are made by the most sophisticated spacecraft ever sent to touch the surface of another world.

Building a supermassive black hole in under a billion years

Decades of astronomy have revealed that supermassive black holes, weighing up to billions of times the mass of the Sun, inhabit the centers of most galaxies, if not all of them. In some galaxies, these black holes power quasars, in which the energetic matter near the black hole emits copious amounts of light. 

This output has helped us spot quasars at great distances, meaning they date from when the Universe was just a few hundred million years old.

The Most Basic Theory About Black Holes Is Wrong

If most people know one thing about black holes, they probably know that nothing can escape from them, not even light.

Yet this most basic tenet about black holes has actually been disproven by the theory of quantum mechanics, explains theoretical physicist Edward Witten of the Institute for Advanced Study in Princeton, NJ, in an essay published online today (Aug. 2) in the journal Science.

Black holes, in the classical picture of physics, are incredibly dense objects where space and time are so warped that nothing can escape from their gravitational grasp. In another essay in the same issue of Science, theoretical physicist Kip Thorne of Caltech describes them as "objects made wholly and solely from curved spacetime."

Cea mai cunoscută teorie legată de găurile negre este greşită!

Toată lumea cunoaşte cel puţin un lucru legat de găurile negre şi anume că nimic nu poate scăpa acestora, nici măcar lumina.

Totuşi, acest principiu de bază legat de găurile negre a fost infirmat de teoria mecanicii cuantice, explică fizicianul Edward Witten de la Institutul pentru Studii Avansate din Princeton, New Jersey.

Double impact crater seen on Mars

PARIS, Aug. 3 (UPI) -- A spacecraft orbiting Mars captured images of interconnected impact craters astronomers say were formed by a single object that split in two just before impact.

The overlapping craters dubbed Sigli and Shambe, photographed by the European Space Agency's Mars Express orbiter, are located in an area of the Red Planet dubbed the Ladon Basin, an ESA release said Thursday.