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  • richardmitnick 8:24 am on March 23, 2017 Permalink | Reply
    Tags: , , Colorado, , EarthSky, National Snow and Ice Data Center (NSIDC) in Boulder, Polar sea ice   

    From EarthSky: “Record low sea ice at both poles” 

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    EarthSky

    March 23, 2017
    Deborah Byrd

    Scientists at NASA and the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado said on March 22, 2017 that Arctic sea ice probably reached its 2017 maximum extent on March 7, and that this year’s maximum represents another record low. Meanwhile, on the opposite side of the planet, on March 3 sea ice around Antarctica hit its lowest extent ever recorded by satellites at the end of summer in the Southern Hemisphere. NASA called it:

    ” … a surprising turn of events after decades of moderate sea ice expansion.”

    Walt Meier, a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland said:

    “It is tempting to say that the record low we are seeing this year is global warming finally catching up with Antarctica. However, this might just be an extreme case of pushing the envelope of year-to-year variability. We’ll need to have several more years of data to be able to say there has been a significant change in the trend.”

    Satellites have been continuously measuring sea ice in 1979, NASA said, and on February 13, the combined Arctic and Antarctic sea ice numbers were at their lowest point since.

    On February 13, total polar sea ice covered 6.26 million square miles (16.21 million square km). That’s 790,000 square miles (2 million square km) less than the average global minimum extent for 1981-2010 – the equivalent of having lost a chunk of sea ice larger than Mexico.

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    These line graphs plot monthly deviations and overall trends in polar sea ice from 1979 to 2017 as measured by satellites. The top line shows the Arctic; the middle shows Antarctica; and the third shows the global, combined total. The graphs depict how much the sea ice concentration moved above or below the long-term average. Arctic and global sea ice totals have moved consistently downward over 38 years. Antarctic trends are more muddled, but they do not offset the great losses in the Arctic. Image via Joshua Stevens/ NASA Earth Observatory.

    NASA explained the seasonal cycle of sea ice’s growth and shrinkage at Earth’s poles, and described specific weather events this year that led to the lower-than-average sea ice:

    The ice floating on top of the Arctic Ocean and surrounding seas shrinks in a seasonal cycle from mid-March until mid-September. As the Arctic temperatures drop in the autumn and winter, the ice cover grows again until it reaches its yearly maximum extent, typically in March. The ring of sea ice around the Antarctic continent behaves in a similar manner, with the calendar flipped: it usually reaches its maximum in September and its minimum in February.

    This winter, a combination of warmer-than-average temperatures, winds unfavorable to ice expansion, and a series of storms halted sea ice growth in the Arctic. This year’s maximum extent, reached on March 7 at 5.57 million square miles (14.42 million square km), is 37,000 square miles (97,00 square km) below the previous record low, which occurred in 2015, and 471,000 square miles (1.22 million square km) smaller than the average maximum extent for 1981-2010.

    Walt Meier added:

    “We started from a low September minimum extent. There was a lot of open ocean water and we saw periods of very slow ice growth in late October and into November, because the water had a lot of accumulated heat that had to be dissipated before ice could grow. The ice formation got a late start and everything lagged behind – it was hard for the sea ice cover to catch up.”

    NASA also said the Arctic’s sea ice maximum extent has dropped by an average of 2.8 percent per decade since 1979. The summertime minimum extent losses are nearly five times larger: 13.5 percent per decade. Besides shrinking in extent, the sea ice cap is also thinning and becoming more vulnerable to the action of ocean waters, winds and warmer temperatures.

    This year’s record low sea ice maximum extent might not necessarily lead to a new record low summertime minimum extent, since weather has a great impact on the melt season’s outcome, Meier said. But, he added:

    ” … it’s guaranteed to be below normal.”

    Meanwhile, in Antarctica, this year’s record low annual sea ice minimum of 815,000 square miles (2.11 million square km) was 71,000 square miles (184,000 square km) below the previous lowest minimum extent in the satellite record, which occurred in 1997. NASA explained:

    “Antarctic sea ice saw an early maximum extent in 2016, followed by a very rapid loss of ice starting in early September. Since November, daily Antarctic sea ice extent has continuously been at its lowest levels in the satellite record. The ice loss slowed down in February.”

    This year’s record low happened just two years after several monthly record high sea ice extents in Antarctica and decades of moderate sea ice growth. The Arctic and Antarctica are very different places; the Arctic is an ocean surrounded by northern continents, while Antarctica is a continent surrounded by ocean. In recent years, climage scientists have pointed to this difference to help explain why the poles were reacting to the trend of warming global temperatures differently.

    But many had said they expected sea ice to begin decreasing in Antarctica, as Earth’s temperatures continue to warm. Claire Parkinson, a senior sea ice researcher at Goddard, said on March 22:

    “There’s a lot of year-to-year variability in both Arctic and Antarctic sea ice, but overall, until last year, the trends in the Antarctic for every single month were toward more sea ice.

    Last year was stunningly different, with prominent sea ice decreases in the Antarctic.

    To think that now the Antarctic sea ice extent is actually reaching a record minimum, that’s definitely of interest.”

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    There’s no real reason Earth’s poles should react in the same way, or at the same rate, to global warming. A fundamental difference between Arctic (left) and Antarctic (right) regions is that the Arctic is a frozen ocean surrounded by continents, while the Antarctic is a frozen continent surrounded by oceanic waters. Map via NOAA/ climate.gov/ researchgate.net.

    Bottom line: Considering both poles in February 2017, Earth essentially lost the equivalent of a chunk of sea ice larger than Mexico, in contrast to the average global minimum for 1981-2010.

    See the full article here .

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  • richardmitnick 8:42 am on March 22, 2017 Permalink | Reply
    Tags: , , , , EarthSky, , Star’s death spiral into black hole   

    From EarthSky: “Star’s death spiral into black hole” 

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    EarthSky

    March 22, 2017
    Eleanor Imster

    NASA said on March 20, 2017 that scientists used data from its Swift satellite to get a comprehensive look at a star’s death spiral into a black hole.


    NASA/SWIFT Telescope

    The star was much like our sun. The black hole contains some 3 million times the mass of our sun and lies at the center of a galaxy 290 million light-years away. As the black hole tore the star apart, it produced what scientists call a tidal disruption event. They’ve labeled this particular event – an eruption of optical, ultraviolet, and X-ray light, which began reaching Earth in 2014 – as ASASSN-14li.

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    Astronomers report the detection of flows of hot, ionized gas in high-resolution X-ray spectra of a nearby tidal disruption event, ASASSN-14li in the galaxy PGC 43234. This artist’s impression shows a supermassive black hole at the center of PGC 43234 accreting mass from a star that dared to venture too close to the galaxy’s center. Image credit: ESA / C. Carreau.

    The scientists have now used Swift’s data to map out how and where these different wavelengths were produced, as the shattered star’s debris circled the black hole. The video animation above is an artist’s depiction of what these scientists believe happened. They said it took awhile for debris from the star to be swallowed up by the black hole.

    Dheeraj Pasham, an astrophysicist at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts, and the lead researcher of the study, said:

    “We discovered brightness changes in X-rays that occurred about a month after similar changes were observed in visible and UV light. We think this means the optical and UV emission arose far from the black hole, where elliptical streams of orbiting matter crashed into each other.”

    Their study was published March 15, 2017 in the Astrophysical Journal Letters.

    A tidal disruption event happens when a star passes too close to a very massive black hole. ASASSN-14li is the closest tidal disruption discovered in 10 years, so of course astronomers are studying it as extensively as they can. During events like this, tidal forces from a black hole may convert the star into a stream of debris. Stellar debris falling toward the black hole doesn’t fall straight in, however, but instead collects into a spinning accretion disk, encircling the hole.

    The accretion disk is the source of all the action, as observed by earthly astronomers.

    Within the disk, star material becomes compressed and heated before eventually spilling over the black hole’s event horizon, the point beyond which nothing can escape and astronomers cannot observe.

    The animation above, from NASA’s Goddard Space Flight Center illustrates:

    … how debris from a tidally disrupted star collides with itself, creating shock waves that emit ultraviolet and optical light far from the black hole. According to Swift observations of ASASSN-14li, these clumps took about a month to fall back to the black hole, where they produced changes in the X-ray emission that correlated with the earlier UV and optical changes.

    According to the scientists, the ASASSN-14li black hole’s event horizon is typically about 13 times bigger in volume than our sun. Meanwhile, the accretion disk formed by the disrupted star might extend to more than twice Earth’s distance from the sun.

    Bottom line: A team of scientists used observations from NASA’s Swift satellite have mapped the death spiral of a star as it was destroyed by the black hole at the center of its galaxy.

    See the full article here .

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  • richardmitnick 8:38 am on March 19, 2017 Permalink | Reply
    Tags: , , , , EarthSky, , TDE's, When galaxies collide black holes eat   

    From EarthSky: “When galaxies collide, black holes eat” 

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    EarthSky

    March 12, 2017
    Deborah Byrd

    When our Milky Way galaxy and neighboring Andromeda galaxy collide, supermassive black holes will have a feast!

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    Artist’s concept of a Tidal Disruption Event, in which a black hole eats a star, in the distant galaxy F01004-2237. As the black hole swallows the star, there’s a release of gravitational energy from the star’s debris. The result is a visible flare. Image via Mark Garlick.

    What’ll our sky look like 5 billion years from now, when our Milky Way galaxy merges with the nearby Andromeda galaxy? If there are any people left to look then [this is false, there will be no people, as our sun will hve in 3 billion years grown into a red giant, consumed Mercury and Venue, and at least fried Earth before eating it] they’ll be able to see flares about every 10 to 100 years, each time our Milky Way’s central supermassive black hole swallows a star. The flares will be visible to the unaided eye [forget it, but still you need to pay your taxes]. They’ll appear much brighter than any other star or planet in the night sky. That’s according to astronomers at the University of Sheffield in England, who say that central, supermassive black holes in colliding galaxies swallow stars some 100 times more often than previously thought.

    Their study was published March 1, 2017 in the peer-reviewed journal Nature Astronomy.

    The study is based on a survey of just 15 galaxies, a very small sample size by astronomical standards. However, in that small sample, the astronomers were surprised to see a black hole swallow a star. Astronomers call this sort of event a tidal distruption event, or TDE. They’d been only been only seen before in surveys of many thousands of galaxies, leading astronomers to believe they were exceptionally rare: only one event every 10,000 to 100,000 years per galaxy.

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    Artist’s concept of Earth’s night sky in 3.75 billion years. The Andromeda galaxy (left) will fill our field of view then, astronomers say, as it heads toward a collision, or merger, with our Milky way galaxy. Image via NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger.

    The 15 galaxies of the University of Sheffield study are doing something those other thousands of galaxies weren’t doing. They’re undergoing collisions with neighboring galaxies. Study co-author James Mullaney said in a statement:

    “Our surprising findings show that the rate of TDEs dramatically increases when galaxies collide. This is likely due to the fact that the collisions lead to large numbers of stars being formed close to the central supermassive black holes in the two galaxies as they merge together.”

    Another study co-author, Rob Spence, said:

    “Our team first observed the 15 colliding galaxies in the sample in 2005, during a previous project.

    However, when we observed the sample again in 2015, we noticed that one galaxy – F01004-2237 – appeared strikingly different. This led us to look at data from the Catalina Sky Survey, which monitors the brightness of objects in the sky over time. We found that in 2010, the brightness of F01004-2237 flared dramatically.”

    Galaxy F01004-2237 – which is 1.7 billion light years from Earth – had flared in a way characteristic of TDEs. These events are known to cause flaring due to energy release, as a star edges toward a galaxy’s central, supermassive black hole.

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    NGC 2207 and IC 2163 are two spiral galaxies in the process of merging, or colliding. If the new study from University of Sheffield is correct, there is a much greater chance for stars to be eaten in these galaxies by their central, supermassive black holes.

    Bottom line: A study from the University of Sheffield shows that collisions – like that predicted for our Milky Way galaxy and neighboring Andromeda galaxy – cause black holes to eat stars some 100 times faster than previously thought.

    See the full article here .

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  • richardmitnick 11:42 am on March 16, 2017 Permalink | Reply
    Tags: , , , EarthSky, Great Barrier Reef is dying   

    From EarthSky: “Great Barrier Reef is dying” 

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    EarthSky

    March 16, 2017
    Deborah Byrd

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    Bleached coral in 2016 on the northern Great Barrier Reef. Image via Terry Hughes et al./Nature.

    Great Barrier Reef – the world’s largest reef system – is being increasingly affected by climate change, according to the authors of a cover story in the March 15, 2017 issue of the peer-reviewed journal Nature. Large sections of the reef are now dead, these scientists report. Marine biologist Terry Hughes of the ARC Center of Excellence for Coral Reef Studies led a group that examined changes in the geographic footprint – that is, the area affected – of mass bleaching events on the Great Barrier Reef over the last two decades. They used aerial and underwater survey data combined with satellite-derived measurements of sea surface temperature. Editors at Nature reported:

    “They show that the cumulative footprint of multiple bleaching events has expanded to encompass virtually all of the Great Barrier Reef, reducing the number and size of potential refuges [for fish and other creatures that live in the reef]. The 2016 bleaching event proved the most severe, affecting 91% of individual reefs.”

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    The NY Times published this map on March 15, 2017, based on information from the ARC Centre of Excellence for Coral Reef Studies. It shows that individual reefs in each region of the Great Barrier Reef lost different amounts of coral in 2016. Numbers show the range of loss for the middle 50% of observations in each region. Study authors told the NY Times this level of destruction wasn’t expected for another 30 years.

    Hughes and colleagues said in their study [Nature]:

    “During 2015–2016, record temperatures triggered a pan-tropical episode of coral bleaching, the third global-scale event since mass bleaching was first documented in the 1980s …

    The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016.

    Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs.”

    According to the website CoralWatch.org:

    Many stressful environmental conditions can lead to bleaching, however, elevated water temperatures due to global warming have been found to be the major cause of the massive bleaching events observed in recent years. As the sea temperatures cool during winter, corals that have not starved may overcome a bleaching event and recover their [symbiotic dinoflagellates (algae)].

    However, even if they survive, their reproductive capacity is reduced, leading to long-term damage to reef systems.

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    In March 2016, researchers could see bleached coral in the northern Great Barrier Reef from the air. Image via James Kerry/ARC Center of Excellence for Coral Reef Studies.

    Bottom line: Authors of a cover story published on March 15, 2017 in the journal Nature called for action to curb warming, to help save coral reefs.

    See the full article here .

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  • richardmitnick 6:27 pm on February 19, 2017 Permalink | Reply
    Tags: , , , , , EarthSky, NAOJ Nobeyama Radio Observatory, Supernova Remnant W44   

    From EarthSky: “Hints of a quiet, stray black hole” 

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    EarthSky
    Via NAOJ Nobeyama Radio Observatory
    No writer credit

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    Supernova Remnant W44. https://earthspacecircle.blogspot.com/2015/12/supernova-remnant-w44.html

    Graduate student Masaya Yamada and professor Tomoharu Oka, both of Keio University, led a research team that was surveying gas clouds around the supernova remnant W44, located 10,000 light-years away from us, when they noticed something unusual. Their statement explained:

    “During the survey, the team found a compact molecular cloud with enigmatic motion. This cloud, [nicknamed] the ‘Bullet,’ has a speed of more than 100 km/second [60 miles/second], which exceeds the speed of sound in interstellar space by more than two orders of magnitude. In addition, this cloud, with the size of two light-years, moves backward against the rotation of the Milky Way galaxy.”

    The energy of motion of the Bullet is many times larger than that injected by the original W44 supernova. The astronomers think this energy must come from a quiet, stray black hole, and they proposed two scenarios to explain the Bullet:

    ” In both cases, a dark and compact gravity source, possibly a black hole, has an important role. One scenario is the ‘explosion model’ in which an expanding gas shell of the supernova remnant passes by a static black hole. The black hole pulls the gas very close to it, giving rise to an explosion, which accelerates the gas toward us after the gas shell has passed the black hole. In this case, the astronomers estimated that the mass of the black hole would 3.5 times the solar mass or larger.

    The other scenario is the ‘irruption model’ in which a high speed black hole storms through a dense gas and the gas is dragged along by the strong gravity of the black hole to form a gas stream. In this case, researchers estimated the mass of the black hole would be 36 times the solar mass or larger. With the present dataset, it is difficult for the team to distinguish which scenario is more likely.”

    Via NAOJ Nobeyama Radio Observatory

    ASTE Atacama Submillimeter telescope
    ASTE Atacama Submillimeter telescope

    Nobeyama Radio Telescope - Copy
    Nobeyama Radio Telescope

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    (a) CO (J=3-2) emissions (color) and 1.4 GHz radio continuum emissions (contours) around the supernova remnant W44. (b) Galactic longitude-velocity diagram of CO (J=3-2) emissions at the galactic latitude of -0.472 degrees. (c -f): Galactic longitude-velocity diagrams of the Bullet in CO (J=1-0), CO (J=3-2), CO (J=4-3), and HCO+ (J=1-0), from left to right. Galactic longitude-velocity diagrams show the speed of the gas at a specific position. Structures elongated in the vertical direction in the diagrams have a large velocity width. Credit: Yamada et al. (Keio University), NAOJ

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    Schematic diagrams of two scenarios for the formation mechanism of the Bullet. (a) explosion model and (b) irruption model. Both diagrams show a part of the shock front produced by the expansion of the supernova remnant W44. The shock wave enters into quiescent gas and compresses it to form dense gas. The Bullet is located in the center of the diagram and has completely different motion compared to the surrounding gas. Credit: Yamada et al. (Keio University)

    These astronomers published their findings in January, 2017 in the peer-reviewed Astrophysical Journal Letters.

    A black hole is a place in space where matter is squeezed into a tiny space, and where gravity pulls so hard that even light can’t escape. Black holes are black. No light comes from them. Up to now, most known stellar black holes are those with companion stars. The black hole pulls gas from the companion, which piles up around it and forms a disk. The disk heats up due to the enormous gravitational pull by the black hole and emits intense radiation.

    On the other hand, if a black hole is floating alone in space – as many must be – its lack of light or any sort of emission would make it very, very hard to find.

    See the full article here .

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  • richardmitnick 1:20 pm on February 5, 2017 Permalink | Reply
    Tags: , , , EarthSky, Maarten Schmidt, , quasi-stellar radio source 3C273,   

    From EarthSky: “Today in science: Quasar mystery solved” A Fascinating Look Back to February 5, 1963 

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    EarthSky

    February 5, 2017
    Deborah Byrd

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    Maarten Schmidt via CalTech

    February 5, 1963. On this date, Caltech astronomer Maarten Schmidt solved a puzzle about the quasi-stellar radio source 3C273 that changed the way we think about our universe.

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    X-ray image of 3C273 and its jet. Today, this quasar is known to lie at the center of a giant elliptical galaxy. Image via Chandra X-ray Observatory.

    This object appeared starlike, like a point of light, with a mysterious jet. But its spectrum – the range of wavelengths of its light – looked odd. Astronomers routinely use spectra to learn the composition of distant objects. But, in 1963, emission lines in the spectrum of 3C273 didn’t appear to match any known chemical elements. Schmidt had a sudden realization that 3C273 contained the very ordinary element hydrogen. He realized that the spectral lines of hydrogen appeared strange because they were highly shifted toward the red end of the spectrum. Such a large red shift could occur if 3C273 were very distant, about three billion light-years away.

    Dr. Schmidt told EarthSky that he recognized immediately the implications of his revelation. He said:

    “This realization came immediately: my wife still remembers that I was pacing up and down much of the evening”

    The implications were just this. To be so far away and still visible, 3C273 must be intrinsically very bright and very powerful. It’s now thought to shine with the light of two trillion stars like our sun. That’s hundreds of times the light of our entire Milky Way galaxy. Yet 3C273 appears to be less than a light-year across, in contrast to 100,000 light-years for our Milky Way.

    So 3C273 is not only distant. It is also exceedingly luminous, implying powerful energy-producing processes unknown in 1963. Schmidt announced his revelation about quasars in the journal Nature on March 16, 1963.

    Today, hundreds of thousands of quasars are known, and many are more distant and more powerful than 3C273. It’s no exaggeration to say they turned the science of astronomy on its ear. Why, for example, are these powerful quasars located so far away in space? Because light travels at a finite speed (186,000 miles per second), we are seeing distant objects in space in the distant past. In other words, quasars existed in early universe. They do not exist in our time. Why?

    In the 1960s, 3C273 and other quasars like it were strong evidence against the Fred Hoyle’s Steady State theory, which suggested that matter is continuously being created as the universe expands, leading to a universe that is the same everywhere. The quasars showed the universe is not the same everywhere and thus helped usher in Big Bang cosmology.

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    Timeline of the universe. A representation of the evolution of the universe over 13.77 billion years. The far left depicts the earliest moment we can now probe, when a period of “inflation” produced a burst of exponential growth in the universe. (Size is depicted by the vertical extent of the grid in this graphic.) For the next several billion years, the expansion of the universe gradually slowed down as the matter in the universe pulled on itself via gravity. More recently, the expansion has begun to speed up again as the repulsive effects of dark energy have come to dominate the expansion of the universe. The afterglow light seen by WMAP was emitted about 375,000 years after inflation and has traversed the universe largely unimpeded since then. The conditions of earlier times are imprinted on this light; it also forms a backlight for later developments of the universe.
    Date circa 2006
    Author NASA/WMAP Science Team

    ESA/Planck supercedes WMAP
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    21 March 2013
    ESA’s Planck satellite has delivered its first all-sky image of the Cosmic Microwave Background (CMB), bringing with it new challenges about our understanding of the origin and evolution of the cosmos. The image has provided the most precise picture of the early Universe so far.

    But Steady State theory had been losing ground, even before 1963. The biggest change caused by Maarten Schmidt’s revelation about the quasar 3C273 was in the way we think about our universe.

    In other words, the idea that 3C273 was extremely luminous, and yet occupied such a relatively small space, suggested powerful energies that astronomers had not contemplated before. 3C273 gave astronomers one of their first hints that we live in a universe of colossal explosive events – and extreme temperatures and luminosities – a place where mysterious black holes abound and play a major role.

    According to a March 2013 email from Caltech:

    In 1963, Schmidt’s discovery gave us an unprecedented look at how the universe behaved at a much younger period in its history – billions of years before the birth of the sun and its planets. Later, Schmidt, along with his colleague Donald Lynden-Bell, discovered that quasars are galaxies harboring supermassive black holes billions of light-years away – not stars in our own galaxy, as was once believed. His seminal work dramatically increased the scale of the observable universe and advanced our present view on the violent nature of the universe in which massive black holes play a dominant role.

    What are quasars? Astronomers today believe that a quasar is a compact region in the center of a galaxy in the early universe. The compact region is thought to surround a central supermassive black hole, much like the black hole thought to reside in the center of our own Milky Way galaxy and many (or most) other galaxies. The powerful luminosity of a quasar is thought to be the result of processes taking place in an accretion disk, or disk of material surrounding the black hole, as these supermassive black holes consume stars that pass too near.

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    ULAS J1120+0641, farthest quasar known as of 2011. The quasar appears as a faint red dot close to the center. Composite image created from the Sloan Digital Sky Survey and the UKIRT Infrared Deep Sky Survey, via Wikimedia Commons.

    SDSS Telescope at Apache Point Observatory, NM, USA
    SDSS Telescope at Apache Point Observatory, NM, USA

    UKIRT, located on Mauna Kea, Hawaii, USA as part of Mauna Kea Observatory
    UKIRT interior
    UKIRT, located on Mauna Kea, Hawaii, USA as part of Mauna Kea Observatory

    The Chinese-born U.S. astrophysicist Hong-Yee Chiu coined the name quasar in May 1964, in the publication Physics Today. He wrote:

    So far, the clumsily long name ‘quasi-stellar radio sources’ is used to describe these objects. Because the nature of these objects is entirely unknown, it is hard to prepare a short, appropriate nomenclature for them so that their essential properties are obvious from their name. For convenience, the abbreviated form ‘quasar’ will be used throughout this paper.

    Today, the farthest known quasar is ULAS J1120+0641. Its co-moving distance is 28.85 billion light-years.

    Bottom line: On February 5 1963, astronomer Maarten Schmidt’s flash of inspiration led to the understanding that quasi-stellar radio sources, or quasars, exist in the very distant universe. Quasars became the most distant, and most luminous, objects known. They changed the way we think about the universe.

    See the full article here .

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  • richardmitnick 12:44 pm on January 6, 2017 Permalink | Reply
    Tags: , , EarthSky, Orion the Hunter easy to spot in January   

    From EarthSky: “Orion the Hunter easy to spot in January” 

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    EarthSky

    January 6, 2017
    Deborah Byrd

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    EarthSky.org

    Tonight – or any January evening – look for the constellation Orion the Hunter. It’s probably the easiest to pick out of all the constellations in the winter sky. It’s identifiable by Orion’s Belt, three medium-bright stars in a short, straight row at the mid-section of the Hunter. See these stars? They are easy to spot on the sky’s dome. As seen from mid-northern latitudes, you’ll find Orion in the southeast at early evening and shining high in the south by late evening (around 10 to 11 p.m. local time). If you live at temperate latitudes to the south of the equator, you’ll see Orion high in your northern sky at this hour. Pick out Orion’s Belt and the nearby bright stars in that part of the sky, and you’ve probably found Orion.

    There’s plenty to see in Orion, too, and it’s easy to find.

    Stars in distinct constellations like Orion look connected, perhaps even gravitationally bound, but usually they aren’t. Certainly Orion’s stars aren’t bound to each other by anything but their general location near one another along a single line of sight from Earth. The stars of Orion just happen to make an easy visual pattern on our sky’s dome.

    Meanwhile, the stars in Orion and most other constellations are located at vastly different distances from each other. For example, notice the two brightest stars in Orion, Betelgeuse and Rigel. Betelgeuse is estimated to be located 522 light-years away, while Rigel’s distance is 773 light-years.

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    Betelgeuse. http://astropixels.com/stars/Betelgeuse-01.html

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    Rigel. http://www.astronomytrek.com/star-facts-rigel/

    On the other hand, those prominent stars in Orion’s Belt are somewhat related. They are all giant stars in a nearby spiral arm of our Milky Way galaxy. These stars’ names are Mintaka, Alnilam, and Alnitak.

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    Mintaka. http://astrologyking.com/mintaka-star-orions-belt/

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    Anlilam. http://www.christiancyberspace.com/cosmic-discovery/html/stars/infopage-Orion’s_Belt.html

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    Alnitak. https://osr.org/blog/astronomy/alnitak/

    Bottom line: At this time of year, the constellation Orion the Hunter takes center stage in the star-studded sky! It’s identifiable by Orion’s Belt, three medium-bright stars in a short, straight row at the mid-section of the Hunter.

    See the full article here .

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  • richardmitnick 8:30 am on December 31, 2016 Permalink | Reply
    Tags: , , , EarthSky,   

    From EarthSky: “How far is a light-year?” 

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    EarthSky

    July 11, 2016 [Year end finds]
    Bruce McClure

    How can we comprehend the distances to the stars? This EarthSky post brings the scale of light-years down to the scale of miles and kilometers.

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    The large yellow shell depicts a light-year; the smaller yellow shell depicts a light-month. Read more about this image at Wikimedia Commons.

    Stars other than our sun are so far distant that astronomers speak of their distances not in terms of kilometers or miles – but in light-years. Light is the fastest-moving stuff in the universe. If we simply express light-years as miles and kilometers, we end up with impossibly huge numbers. But the 20th century astronomer Robert Burnham Jr. – author of Burnham’s Celestial Handbook – devised an ingenious way to portray the distance of one light-year and ultimately of expressing the distance scale of the universe, in understandable terms.

    He did this by relating the light-year to the Astronomical Unit – the Earth-sun distance.

    One Astronomical Unit, or AU, equals about 93 million miles (150 million km).

    Another way of looking at it: the Astronomical Unit is a bit more than 8 light-minutes in distance.

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    A light beam takes 8 minutes to travel the 93 million miles (150 million km) from the sun to the Earth. Image via Brews OHare on Wikimedia Commons.

    Robert Burnham noticed that, quite by coincidence, the number of astronomical units in one light-year and the number of inches in one mile are virtually the same.

    For general reference, there are 63,000 astronomical units in one light-year, and 63,000 inches (160,000 cm) in one mile (1.6 km).

    This wonderful coincidence enables us to bring the light-year down to Earth. If we scale the astronomical unit – the Earth-sun distance – at one inch, then the light-year on this scale represents one mile (1.6 km).

    The closest star to Earth, other than the sun, is Alpha Centauri at some 4.4 light-years away. Scaling the Earth-sun distance at one inch places this star at 4.4 miles (7 km) distant.

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    The red star in the center of this picture is Proxima Centauri, our sun’s nearest neighbor among the stars. A beam of light from this star takes about 4 years to travel to Earth. Image via hyperphysics.phy-astr.gsu.edu

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker
    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    Scaling the Astronomical Unit at one inch (2.5 cm), here are distances to various bright stars, star clusters and galaxies:

    Alpha Centauri: 4 miles (6.4 km)

    Sirius: 9 miles (14.5 km)

    Vega: 25 miles (40 km)

    Fomalhaut: 25 miles (40 km)

    Arcturus: 37 miles (60 km)

    Antares: 600 miles (966 km)

    Pleiades open star cluster: 440 miles (708 km)

    Hercules globular star cluster (M13): 24,000 miles (38,600 km)

    Center of Milky Way galaxy: 27,000 miles (43,500 km)

    Great Andromeda galaxy (M31): 2,300,000 miles (3,700,000 km)

    Whirlpool galaxy (M51): 37,000,000 miles (60,000,000 km)

    Sombrero galaxy (M104): 65,000,000 miles (105,000,000 km)

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    There are 33 stars within 12.5 light years of our sun. Image via Atlas of the Universe.

    Light is the fastest-moving stuff in the universe. It travels at an incredible 186,000 miles (300,000 km) per second.

    That’s very fast. If you could travel at the speed of light, you would be able to circle the Earth’s equator about 7.5 times in just one second!

    A light-second is the distance light travels in one second, or 7.5 times the distance around Earth’s equator. A light-year is the distance light travels in one year.

    How far is that? Multiply the number of seconds in one year by the number of miles or kilometers that light travels in one second, and there you have it: one light-year. It’s about 5.88 trillion miles (9.5 trillion km).

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    This scale starts close to home but takes us all the way out to the Andromeda Galaxy, the most distant object most people can see with the unaided eye. Image via Bob King / Skyandtelescope.com.

    Bottom line: The scale of light-years expressed as miles and kilometers.

    See the full article here .

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  • richardmitnick 8:48 am on December 27, 2016 Permalink | Reply
    Tags: , , , , EarthSky, , Witnessing the birth of today’s stars   

    From EarthSky: “Witnessing the birth of today’s stars” 

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    EarthSky

    December 27, 2016
    Deborah Byrd

    Dust shrouds the era of distant galaxies, in which most of today’s stars were born 10 billion years ago. Astronomers used radio telescopes to pierce the dust.

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    Radio/Optical combination images of distant galaxies as seen with NSF’s Very Large Array and NASA’s Hubble Space Telescope. Their distances from Earth are indicated in the top set of images. Images via K. Trisupatsilp, NRAO/ AUI/ NSF/ NASA.

    Due to the finite speed of light, looking outward in space is the same as looking back in time. So it would seem simple to peer back to the birth of the first stars, just by looking very far away. There was an era of rapid star formation, early in the history of our universe, 10 billion years ago. The first stars – and, in fact, since most stars are very long-lived – most stars still around today were born then. But the early birthplaces of most modern stars are shrouded in dust. Now astronomers say they’ve gotten their first clear look this distant time and place in our universe, during the era when most of today’s stars were born, using radio telescopes. Their paper was published in the peer-reviewed Astrophysical Journal.

    Astronomer Wiphu Rujopakam of the University of Tokyo and Chulalongkorn University in Bangkok, who is lead author of new research paper, explained:

    “We knew that galaxies [10 billion years ago] were forming stars prolifically, but we didn’t know what those galaxies looked like, because they are shrouded in so much dust that almost no visible light escapes them.”

    And that’s why, for example, the Hubble Deep Fields – very long exposures in visible light which allowed astronomers to look extremely far away in space and back in time – don’t reveal everything about that distant era.

    Unlike visible light, radio waves can penetrate this dust. But powerful radio telescopes are needed to do it. These astronomers used the recently upgraded and renamed Very Large Array or VLA, a radio telescope located on the Plains of San Agustin, some 50 miles (80 km) west of Socorro, New Mexico.

    NRAO/VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA
    NRAO/VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    They also used the Atacama Large Millimeter/submillimeter Array or ALMA in northern Chile, which officially went online as recently as 2013.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at  Chajnantor plateau, at 5,000 metres
    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    The astronomers chose to peer at the small area of sky previously observed in the Hubble Ultra Deep Field.

    Hubble Ultra Deep Field
    Hubble Ultra Deep Field

    The astronomers say the new observations have answered longstanding questions about mechanisms responsible for star formation in those early galaxies. In the galaxies they studied, for example, they found star formation most frequently occured throughout the galaxies. That’s in contrast to closer, younger galaxies exhibiting high rates for star formation today. In those relatively nearby galaxies, most star formation takes place in much-smaller regions of the galaxies.

    The new radio images obtained in this recent study were the most sensitive ever made by the Very Large Array. Astronomer Preshanth Jagannathan of the National Radio Astronomy Observatory (NRAO), a co-author on the study, said:

    “If you took your cellphone, which transmits a weak radio signal, and put it at more than twice the distance to Pluto, near the outer edge of the solar system, its signal would be roughly as strong as what we detected from these galaxies.”

    Bottom line: Astronomers have used radio telescopes to obtain a first-ever look at the distant galaxies where most of today’s stars were born, 10 billion years ago.

    See the full article here .

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  • richardmitnick 10:17 am on December 14, 2016 Permalink | Reply
    Tags: , , EarthSky, Tycho Brahe   

    From EarthSky: “Today in science: Tycho Brahe” 

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    EarthSky

    December 14, 2016
    Daniela Breitman

    Tycho Brahe is known for his partying, his prosthetic nose, and for being one of the greatest astronomers of all time.

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    Heroes of Space: Tycho Brahe. https://www.spaceanswers.com/astronomy/heroes-of-space-tycho-brahe/

    December 14, 1546. Today is Tycho Brahe’s 470th birthday. He was so influential that many astronomers today call him simply Tycho. We remember him for his golden nose, and for his highly accurate measurements of the positions of the planets and of over 777 fixed stars. Later, Tycho’s assistant, Johannes Kepler, used his master’s planet and star measurements to revolutionize physics and astronomy with his three laws of planetary motion.

    Tycho was born shortly before the invention of telescopes, in Denmark, on December 14, 1546. He grew up with his wealthy uncle who paid for his education in law at the University of Copenhagen from 1559 to 1562. On August 21, 1560, a total eclipse of the sun diverted Tycho’s course toward astronomy. The 14-year-old Tycho was said to be amazed beyond words, and his passion for astronomy was born. From that day, Tycho divided his time between law, to accommodate his uncle’s wishes, and astronomy to satisfy his own curiosity. His mathematics professor helped him with the only astronomy book available: one of Ptolemy’s works describing the geocentric – or Earth-centered – model of the universe.

    After he finished his studies at the University of Copenhagen, Tycho’s uncle sent him to the University of Leipzig for more studies until 1565. In 1563, Tycho made his first recoded astronomical observation, of the conjunction of Jupiter and Saturn. Shortly afterwards, he found out that such events were already predicted in various almanacs, but, at that time, were extremely inaccurate. He decided to devote himself to correcting the existing predictions.

    It was in 1566, while dueling with swords with his third cousin, that Tycho lost part of his nose. Afterwards, he wore a metal prosthetic nose.

    For the next five years, after completing his studies, he travelled across Europe and collected instruments for astronomical observation. Around 1571, after inheriting from his uncle and father, Tycho settled in a castle on what’s now an island of Sweden. A few years later, he constructed a small and now-famous observatory that he called Uraniborg, as a tribute to Urania, the Muse of Astronomy.

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    Tycho’s castle – site of one of the world’s most famous observatories – Uraniborg on the island of Hven, built between 1576 and 1580. This depiction of Uraniborg’s main building is from copper etching of Blaeu’s Atlas Major, published in 1663. Image via Wikimedia Commons.

    Tycho used his money on things other than astronomy. If he’d lived in modern times, he’d have been called a party animal and had regular guests with whom to drink. He even had a jester. Some say he also had a tame elk who died from falling down the stairs after drinking too much beer.

    On November 11, 1572, the most amazing event happened in front of Tycho’s eyes: he saw a new star appear, shining more brightly than than the sky’s third-brightest object (after the sun and moon), the planet Venus. The “new” star appears in the direction to the constellation Cassiopeia the Queen. He wrote:

    “When, according to my habit, I was contemplating the stars in a clear sky, I noticed that a new and unusual star, surpassing the other stars in brilliancy, was shining almost directly above my head. And since I had almost from boyhood known all the stars of the heavens perfectly . . . it was quite evident to me that there had never before been any star in that place in the sky, even the smallest, to say nothing of a star so conspicuously bright as this. I was so astonished at this sight that I was not ashamed to doubt the trustworthiness of my own eyes.”

    This was a very worrisome prospect for his time, when the sky was supposed to be a symbol for perfection and constancy. In addition to this new star, Copernican Theory already rattled the ideology of the time. This event was the subject of Tycho’s first paper that confirmed his capability as an astronomer. He wrote:

    “I conclude, therefore, that this star is not some kind of comet or a fiery meteor… but that it is a star shining in the firmament itself – one that has never previously been seen before our time, in any age since the beginning of the world.”

    Today, we know this star was a supernova, one of the very few seen in recorded history. In honor of the great astronomer whose mind so openly accepted it, the supernova of 1572 is sometimes called Tycho’s Star [SN 1572].

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    Tycho’s Supernova Remnant. In 1572, the Danish astronomer Tycho Brahe observed and studied the explosion of a star that became known as Tycho’s supernova. More than four centuries later, Chandra’s image of the supernova remnant shows an expanding bubble of multimillion degree debris (green and red) inside a more rapidly moving shell of extremely high energy electrons (filamentary blue). As a huge ball of exploding plasma, it was Irving Langmuir who coined the name plasma because of its similarity to blood plasma, and Hannes Alfvén who noted its cellular nature. The filamentary blue outer shell of X-ray emitting high-speed electrons is also a characteristic of plasmas. This is a false-colour x-ray image in which the energy levels (in keV) of the x-rays have been assigned a colours as follows: Red 0.95-1.26 keV, Green 1.63-2.26 keV, Blue 4.1-6.1 keV. All x-rays images must use processed colours since x-rays (as are radio waves, infra-red) are invisible to the human eye. But they are not invisible to suitable equipment, such as x-ray telescopes. The red and green bands highlight the expanding cloud of plasma with temperatures in the millions of degrees.
    Date 29 April 2003
    Source http://chandra.harvard.edu/photo/2005/tycho/
    Author NASA/CXC/Rutgers/J.Warren & J.Hughes et al.

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    Tycho’s Armillary Via Wikimedia Commons.

    Throughout his life, Brahe was also an artist. He loved making things, such as his astronomical instruments, look beautiful. Above is his plan for an armillary, an instrument used to measure the positions of celestial objects. The circles are divided into degrees. Notice the amount of detail and decoration.

    It was around 1600, a year before Tycho’s death, that Kepler entered the picture. Kepler believed in Copernican theory and was trying to explain planetary motion, especially the issue with the retrograde motion of Mars. Kepler understood that he needed the most accurate measurement to figure out this puzzle and so he set out to see Tycho and obtain them.

    Tycho wasn’t very cooperative at first. In fact, the two weren’t getting along very well. Kepler was finally able to get his hands on Tycho’s observations (it is unclear how, some say he might have stolen them).

    He used them to devise his three laws of planetary motion, which became the groundwork for later revelations about gravity by Isaac Newton.

    Tycho died in 1600 due to a bladder issue. The circumstances around his death were strange, some say … as strange as his life as a whole.

    See the full article here .

    Please help promote STEM in your local schools.

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