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Tag: Space observatory

  • Killer Asteroids Heading NASA Photos Video

    Asteroids,
    This chart illustrates how infrared is used to more accurately determine an asteroid‘s size.
    Credit: NASA/JPL-CaltechView full size image
    Asteroids.
    Asteroid 2013 002 as mapped by NASA’s NEP program (Image: NASA)

    NASA’s Wide-field Infrared Survey Explorer (WISE), an infrared space telescope, mapped the asteroid population near Earth and elsewhere in the solar system. The asteroid survey, which NASA says is the most accurate ever performed, also lowered the estimated number of giant near-Earth asteroids — space rocks the size of a mountain or larger — from 1,000 to 981, with about 911 of those already known, researchers said.

    “The risk of a really large asteroid impacting the Earth before we could find and warn of it has been substantially reduced,” said Tim Spahr, the director of the Minor Planet Center at the Harvard Smithsonian Center for Astrophysics in Cambridge, Mass.

    Getting WISE to asteroids

    By the end of the WISE telescope’s extended mission, called NEOWISE, last year, astronomers had found 90 percent of the largest asteroids near our planet, NASA scientists said, which met the goal that was set forth by Congress in 1998.

    The WISE space telescope mapped the entire sky twice between January 2010 and February 2011, surveying near-Earth asteroids, brown dwarfs, galaxies and other deep space objects in infrared light. As part of its near-Earth asteroid search, the space observatory scanned for space rocks that orbited within 120 million miles (195 million kilometers) of the sun. The Earth is about 93 million miles (150 million km) from the sun. [Video: Killer Asteroids, We’re WISE to You .Now

    Source: Space.com

    http://www.space.com/13132-potentially-killer-asteroids-earth-nasa.html

     

     

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  • Astronomers Reveal First Objects In Our Universe-Video.

    June 1, 2007 — Astronomers removed light from closer and better known galaxies and stars from pictures taken with the Spitzer Space Telescope. The remaining images are believed to be the first objects in space, 13 billion light years away.

    The first stars in our universe are long gone, but their light still shines, giving us a peek at what the universe looked like in its early years.
    Astrophysicists believe they’ve spotted a faint glow from stars born at the beginning of time. Harvey Moseley, Ph.D., an astrophysicist at the NASA Goddard Space Flight Center in Greenbelt, Maryland, says, “The reason they’re faint is just because they’re very, very far away, they’re over at the far edge of the universe.”
    After the big bang, the universe stayed dark for about 200 million years. Now, new pictures reveal the first light from objects 13 billion light years away, the infants of our universe. “So, we’re seeing what sometimes people call the first light in the universe, which formed after the big bang,” Dr. Moseley explains.
    Using pictures taken with the Spitzer Space Telescope, scientists first removed light from closer stars and galaxies. The light areas left in the background are believed to be the first objects in space. Alexander Kashlinsky, Ph.D., astrophysicist at the NASA Goddard Space Flight Center, says, “The early universe was a very hot place in this sense, like it was filled with objects that have been emitting light much more furiously than today.”
    Researchers say the objects are either stars, hundreds of times more massive than our own sun, or enormous black holes. Either way, the pictures bring us one step closer to learning how the universe was born. NASA’s planned James Webb Space Telescope will be able to identify the nature of the newfound clusters and determine if they are stars or black holes.
    BACKGROUND: Using a telescope as a time machine, scientists at NASA’s Goddard Space Flight Center are closer to identifying the first objects of the universe. The latest observations from the Spitzer Space Telescope suggest that infrared light detected in a prior study comes from clusters of bright objects that lived within the first billion years after the Big Bang.
    THE DARK AGE: According to current science, space, time and matter originated 13.7 billion years ago in a tremendous explosion called the Big Bang. A few hundred million years later, the first stars formed, ending the “dark age” of the universe. Astronomers believe the objects observed by the Spitzer telescope are either the first stars — hundreds of times more massive than our sun — or voracious black holes that are consuming gas and spilling out tons of energy. If they turn out to be stars, then the clusters might be the first mini-galaxies. Our own Milky Way was probably created when mini-galaxies like these merged.
    IN THE INFRARED: The Spitzer scientists were looking specifically at the cosmic infrared background of the universe, a diffuse light from the early epoch when structure first emerged in the cosmos. A prior study reported in 2005 detected infrared light, suggesting that it originated from clumps of the very first objects in the universe. This second analysis indicates that this patchy light is scattered across the entire sky and comes from clusters of bright, monstrous objects more than 13 billion light-years away. Although that light began its journey as ultraviolet or visible light, by the time it reached earth, its wavelengths had been stretched into the infrared by the growing space-time that causes the universe’s expansion. Based on the strength of the infrared light signal, they concluded that the total amount of energy produced by the objects was so large, only very large stars or black holes consuming a lot of matter would be capable of emitting it. Other parts of the cosmic infrared background are from distant starlight absorbed by dust and re-emitted as infrared light.
    SEEING IS BELIEVING: When we peer into space with a telescope, we are actually looking back in time. Telescopes detect emitted light, and the light that reaches us from the closest galaxy, Andromeda, for instance, has taken two million years to reach us. The Spitzer telescope looked at the first brilliant objects to exist in our universe. The Spitzer telescope scanned five areas of the sky for about 25 hours per region, collecting light even from the faintest of objects. Then astronomers meticulously subtracted light from things that were in the way, such as foreground galaxies and dust in our solar system, or in interstellar clouds. When all that was left was the most ancient light, the scientists studied fluctuations in the intensity of the infrared brightness, revealing a clustering of objects to produce the observed light pattern.
    The American Astronomical Society contributed to the information contained in the video portion of this report.
    http://www.sciencedaily.com/videos/2007/0607-first_stars_in_the_universe.htm

  • Hubble Reaches ‘Undiscovered Country’ of Most Distant Primeval Galaxies

    Mind boggling in terms of size and the Time Factor.Please see the Image, by following the link, enlarge the picture and read my blog TIME-A Nonlinear Theory.Would be interesting.
    ScienceDaily (Jan. 5, 2010) — NASA’s Hubble Space Telescope has broken the distance limit for galaxies and uncovered a primordial population of compact and ultra-blue galaxies that have never been seen before.

    The deeper Hubble looks into space, the farther back in time it looks, because light takes billions of years to cross the observable universe. This makes Hubble a powerful “time machine” that allows astronomers to see galaxies as they were 13 billion years ago, just 600 million to 800 million years after the Big Bang.
    The data from Hubble’s new infrared camera, the Wide Field Camera 3 (WFC3), on the Ultra Deep Field (taken in August 2009) have been analyzed by no less than five international teams of astronomers. A total of 15 papers have been submitted to date by astronomers worldwide. Some of these early results are being presented by various team members on Jan. 6, 2010, at the 215th meeting of the American Astronomical Society in Washington, D.C.
    “With the rejuvenated Hubble and its new instruments, we are now entering unchartered territory that is ripe for new discoveries,” says Garth Illingworth of the University of California, Santa Cruz, leader of the survey team that was awarded the time to take the new WFC3 infrared data on the Hubble Ultra Deep Field (imaged in visible light by the Advanced Camera for Surveys in 2004). “The deepest-ever near-infrared view of the universe — the HUDF09 image — has now been combined with the deepest-ever optical image — the original HUDF (taken in 2004) — to push back the frontiers of the searches for the first galaxies and to explore their nature,” Illingworth says.
    Rychard Bouwens of the University of California, Santa Cruz, a member of Illingworth’s team and leader of a paper on the striking properties of these galaxies, says that, “the faintest galaxies are now showing signs of linkage to their origins from the first stars. They are so blue that they must be extremely deficient in heavy elements, thus representing a population that has nearly primordial characteristics.”
    James Dunlop of the University of Edinburgh, agrees. “These galaxies could have roots stretching into an earlier population of stars. There must be a substantial component of galaxies beyond Hubble’s detection limit.”
    Three teams worked hard to find these new galaxies and did so in a burst of papers immediately after the data were released in September, soon followed by a fourth team, and later a fifth team. The existence of these newly found galaxies pushes back the time when galaxies began to form to before 500-600 million years after the Big Bang. This is good news for astronomers building the much more powerful James Webb Space Telescope (planned for launch in 2014), which will allow astronomers to study the detailed nature of primordial galaxies and discover many more even farther away. There should be a lot for Webb to hunt for.
    The deep observations also demonstrate the progressive buildup of galaxies and provide further support for the hierarchical model of galaxy assembly where small objects accrete mass, or merge, to form bigger objects over a smooth and steady but dramatic process of collision and agglomeration. It’s like streams merging into tributaries and then into a bay.
    These galaxies are as small as 1/20th the Milky Way’s diameter,” reports Pascal Oesch of the Swiss Federal Institute of Technology in Zurich. “Yet they are the very building blocks from which the great galaxies of today, like our own Milky Way, ultimately formed,” explains Marcella Carollo, also of the Swiss Federal Institute of Technology in Zurich. Oesch and Carollo are members of Illingworth’s team.
    These newly found objects are crucial to understanding the evolutionary link between the birth of the first stars, the formation of the first galaxies, and the sequence of evolutionary events that resulted in the assembly of our Milky Way and the other “mature” elliptical and majestic spiral galaxies in today’s universe.
    The HUDF09 team also combined the new Hubble data with observations from NASA’s Spitzer Space Telescope to estimate the ages and masses of these primordial galaxies. “The masses are just 1 percent of those of the Milky Way,” explains team member Ivo Labbe of the Carnegie Institute of Washington, leader of two papers on the data from the combined NASA Great Observatories. He further noted that “to our surprise, the results show that these galaxies at 700 million years after the Big Bang must have started forming stars hundreds of millions of years earlier, pushing back the time of the earliest star formation in the universe.”
    The results are gleaned from the HUDF09 observations, which are deep enough at near-infrared wavelengths to reveal galaxies at redshifts from z=7 to beyond redshift z=8. (The redshift value z is a measure of the stretching of the wavelength or “reddening” of starlight due to the expansion of space.) The clear detection of galaxies between z=7 and z=8.5 corresponds to “look-back times” of approximately 12.9 billion years to 13.1 billion years ago.
    “This is about as far as we can go to do detailed science with the new HUDF09 image. This shows just how much the James Webb Space Telescope (JWST) is needed to unearth the secrets of the first galaxies,” says Illingworth. The challenge is that spectroscopy is needed to provide definitive redshift values, but the objects are too faint for spectroscopic observations (until JWST is launched). Therefore, the redshifts are inferred by the galaxies’ apparent colors through a now very well-established technique.
    The teams are finding that the number of galaxies per unit of volume of space drops off smoothly with increasing distance, and the HUDF09 team has also found that the galaxies become surprisingly blue intrinsically. The ultra-blue galaxies are extreme examples of objects that appear so blue because they may be deficient in heavier elements, and as a result, quite free of the dust that reddens light through scattering.
    A longstanding problem with these findings is that it still appears that these early galaxies did not put out enough radiation to “reionize” the early universe by stripping electrons off the neutral hydrogen that cooled after the Big Bang. This “reionization” event occurred between about 400 million and 900 million years after the Big Bang, but astronomers still don’t know which sources of light caused it to happen. These new galaxies are being seen right in this important epoch in the evolution of the universe.
    Perhaps the density of very faint galaxies below the current detection limit is so high that there may be enough of them to support reionization. Or there was an earlier wave of galaxy formation that decayed and then was “rebooted” by a second wave of galaxy formation. Or, possibly the early galaxies were extraordinarily efficient at reionizing the universe.
    Due to these uncertainties it is not clear what type of object or evolutionary process did the “heavy lifting” by ionizing the young universe. The calculations remain rather uncertain, and so galaxies may do more than currently expected, or astronomers may need to invoke other phenomena such as mini-quasars (active supermassive black holes in the cores of galaxies) — current estimates suggest however that quasars are even less likely than galaxies to be the cause of reionization. This is an enigma that still challenges astronomers and the very best telescopes.
    “As we look back into the epoch of the first galaxies in the universe, from a redshift of 6 to a redshift of 8 and possibly beyond, these new observations indicate that we are likely seeing the end of reionization, and perhaps even into the reionization era, which is the last major phase transition of the gas in the universe,” says Rogier Windhorst of Arizona State University, leader of one of the other teams that analyzed the WFC3 data. “Though the exact interpretation of these new results remains under debate, these new WFC3 data may provide an exciting new view of how galaxy formation proceeded during and at the end of the reionization era.”
    Hubble’s WFC3/IR camera was able to make deep exposures to uncover new galaxies at roughly 40 times greater efficiency than its earlier infrared camera that was installed in 1997. The WFC3/IR brought new infrared technology to Hubble and accomplished in four days of observing what would have previously taken almost half a year for Hubble to do.
    http://www.sciencedaily.com/releases/2010/01/100105105209.htm