Cometa Ison a supravietuit apropierea de soare – Comet Ison’s full swing around the sun – Coplesit de Creatia lui Dumnezeu

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Cometa ISON a supravieţuit trecerii sale pe lângă Soare, joi, şi a fost denumită „cometa zombie” de către astronomii americani, care consideră că acest corp ceresc neobişnuit „s-a întors dintre morţi”.

Trecerea cometei ISON pe lângă Soare s-a produs cu o viteză uluitoare, care a atins 1,4 milioane de kilometri pe oră. Concluziile iniţiale ale experţilor indicau faptul că ISON, un bulgăr uriaş de gheaţă şi praf stelar, venit de la marginea Sistemului Solar, nu a supravieţuit temperaturilor de câteva mii de grade Celsius în timpul apropierii de Soare şi că acest corp ceresc s-a dezintegrat.

Vineri, însă, spre surpriza specialiştilor, o pată strălucitoare şi-a făcut apariţia pe imaginile captate de sonda Soho, exact în locul în care era aşteptată traiectoria cometei ISON.

„Nu ştim deocamdată dacă este vorba de resturi rămase din cometă sau dacă o parte din nucleul cometei a supravieţuit”, afirmă NASA. Analizele preliminare sugerează faptul că cel puţin o parte din nucleul cometei ISON este intact. Deocamdată este prea devreme pentru ca astronomii să poată spune dacă ISON a rămas intactă sau a fost fragmentată şi să indice procentul din masa iniţială care a fost conservat, dar, în orice caz, masa rămasă este suficientă pentru a forma un nucleu cu o activitate vizibilă.

Sursa: Vezi mai multe faze cu apropierea de soare, imagini capturate de diferite telescoape NASA, din diferite unghiuri. Cometa o veti vedea venind din partea dreapta, jos a ecranului, va inconjura soarele si se va reintoarce.


After several days of continued observations, scientists continue to work to determine and to understand the fate of Comet ISON: There’s no doubt that the comet shrank in size considerably as it rounded the sun and there’s no doubt that something made it out on the other side to shoot back into space. The question remains as to whether the bright spot seen moving away from the sun was simply debris, or whether a small nucleus of the original ball of ice was still there. Regardless, it is likely that it is now only dust.

Comet ISON, which began its journey from the Oort Cloud some 3 million years ago, made its closest approach to the sun on Nov. 28, 2013. The comet was visible in instruments on NASA’s Solar Terrestrial Relations Observatory, or STEREO, and the joint European Space Agency/NASA Solar and Heliospheric Observatory, or SOHO, via images called coronagraphs. Coronagraphs block out the sun and a considerable distance around it, in order to better observe the dim structures in the sun’s atmosphere, the corona. As such, there was a period of several hours when the comet was obscured in these images, blocked from view along with the sun. During this period of time, NASA’s Solar Dynamics Observatory could not see the comet, leading many scientists to surmise that the comet had disintegrated completely. However, something did reappear in SOHO and STEREO coronagraphs some time later – though it was significantly less bright.
Whether that spot of light was merely a cloud of dust that once was a comet, or if it still had a nucleus – a small ball of its original, icy material – intact, is still unclear. It seems likely that as of Dec. 1, there was no nucleus left. By monitoring its changes in brightness over time, scientists can estimate whether there’s a nucleus or not, but our best chance at knowing for sure will be if the Hubble Space Telescope makes observations later in December 2013.
Regardless of its fate, Comet ISON did not disappoint researchers. Over the last year, observatories around the world and in space gathered one of the largest sets of comet observations of all time, which should provide fodder for study for years to come. The number of space-based, ground-based, and amateur observations were unprecedented, with twelve NASA space-based assets observing over the past year.


Quasars…region in the center of a massive galaxy surrounding a supermassive black hole

What are Quasars ?

A Primordial Quasar
Drawing Credit: Wolfram Freudling et al. (STECF), ESO, ESA, NASA

Explanation: What did the first quasars look like? The nearest quasars are now known to be supermassive black holes in the centers of galaxies. Gas and dust that falls toward a quasar glows brightly, sometimes outglowing the entire home galaxy. The quasars that formed in the first billion years of the universe are more mysterious, though, with even the nature of the surrounding gas still unknown. Above, an artist’s impression shows a primordial quasar as it might have been, surrounded by sheets of gas, dust, stars, and early star clusters. Exacting observations of three distant quasars now indicate emission of very specific colors of the element iron. These Hubble Space Telescope observations, which bolster recent results from the WMAP mission, indicate that a whole complete cycle of stars was born, created this iron, and died within the first few hundred million years of the universe.

A quasi-stellar radio source („quasar”) is a very energetic and distant active galactic nucleus. Quasars are the most luminous objects in the universe. Quasars were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than extended sources similar to galaxies.

While there was initially some controversy over the nature of these objects—as recently as the early 1980s, there was no clear consensus as to their nature—there is now a scientific consensus that a quasar is a compact region in the center of a massive galaxy surrounding its central supermassive black hole. Its size is 10–10,000 times the Schwarzschild radius of the black hole. The quasar is powered by an accretion disc around the black hole.

Quasars show a very high redshift, which is an effect of the expansion of the universe between the quasar and the Earth.[1] They are the most luminous, powerful, and energetic objects known in the universe. They tend to inhabit the very centers of active young galaxies and can emit up to a thousand times the energy output of the Milky Way. When combined with Hubble’s law, the implication of the redshift is that the quasars are very distant—and thus, it follows, objects from much earlier in the universe’s history. The most luminous quasars radiate at a rate that can exceed the output of average galaxies, equivalent to one trillion (1012) suns. This radiation is emitted across the spectrum, almost equally, from X-rays to the far-infrared with a peak in the ultraviolet-optical bands, with some quasars also being strong sources of radio emission and of gamma-rays. In early optical images, quasars looked like single points of light (i.e. point sources), indistinguishable from stars, except for their peculiar spectra. With infrared telescopes and the Hubble Space Telescope, the „host galaxies” surrounding the quasars have been identified in some cases.[2] These galaxies are normally too dim to be seen against the glare of the quasar, except with these special techniques. Most quasars cannot be seen with small telescopes, but 3C 273, with an average apparent magnitude of 12.9, is an exception. At a distance of 2.44 billion light-years, it is one of the most distant objects directly observable with amateur equipment.

More than 200,000 quasars are known, most from the Sloan Digital Sky Survey. Quasars have all the same properties as active galaxies, but are more powerful. You can read more here and enter the Astronomy portal here.

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