Mystery of cosmic rays' origin finally solved - physics-math - 14 February 2013 Video: Stellar cataclysm The protons that constantly smack into Earth's atmosphere at near the speed of light get their huge energies from exploding stars. At least that's what physicists and astronomers had long suspected, but direct evidence for the idea has been difficult to come by – until now. Cosmic rays are any charged particles arriving at Earth from space. "It's a 100-year-old mystery," says Stefan Funk of the SLAC National Accelerator Laboratory in Menlo Park, California. Physicists suspected that one possible source was the violent outburst of a supernova within the Milky Way. Because protons are charged, they can get caught in magnetic fields which carry them back and forth across the shock many times, like a tennis ball bouncing back and forth across a net. "Eventually their energy gets large enough that they can leave the shock region," Funk says. Total scramble But magnetic fields can also deflect cosmic rays on their way to our detectors. More From New Scientist
CMB Cosmic Background Radiation : One of the foremost cosmological discoveries was the detection of the cosmic background radiation. The discovery of an expanding Universe by Hubble was critical to our understanding of the origin of the Universe, known as the Big Bang. The steady state theory avoids the idea of Creation by assuming that the Universe has been expanding forever. The creation of new matter would violate the conservation of matter principle, but the amount needed would only be one atom per cubic meter per 100 years to match the expansion rate given by Hubble's constant. The discovery of the cosmic microwave background (CMB) confirmed the explosive nature to the origin of our Universe. Most of the photons that you see with your naked eye at night come from the centers of stars. Cosmic background photons have their origin at the matter/anti-matter annihilation era and, thus, were formed as gamma-rays. Where are the CMB photons at the moment? CMB Fluctuations :
Observable universe The surface of last scattering is the collection of points in space at the exact distance that photons from the time of photon decoupling just reach us today. These are the photons we detect today as cosmic microwave background radiation (CMBR). However, with future technology, it may be possible to observe the still older neutrino background, or even more distant events via gravitational waves (which also should move at the speed of light). Sometimes astrophysicists distinguish between the visible universe, which includes only signals emitted since recombination—and the observable universe, which includes signals since the beginning of the cosmological expansion (the Big Bang in traditional cosmology, the end of the inflationary epoch in modern cosmology). The universe versus the observable universe If the universe is finite but unbounded, it is also possible that the universe is smaller than the observable universe. Size Misconceptions 13.8 billion light-years
Forensic astronomy Forensic astronomy is the use of astronomy, the scientific study of celestial objects, to determine past celestial constellations. This has been used, if relatively rarely, in forensic science (that is, for solving problems of relevance to the legal system) and for resolving historical problems more generally, notably issues in art history. Forensic science As a forensic science in the strict sense of the term, astronomical knowledge can help resolve certain legal questions. History By extension, the adjective "forensic" has come to be used for any detailed analysis of past events, whether related to legal questions or not, and so the determination of past celestial constellations more generally is now increasingly referred to as "forensic astronomy". See also Forensic meteorology References External links Smithsonian Magazine: Forensic Astronomer Solves Fine Arts Puzzles
Astrometry Illustration of the use of interferometry in the optical wavelength range to determine precise positions of stars. Courtesy NASA/JPL-Caltech Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. The information obtained by astrometric measurements provides information on the kinematics and physical origin of our Solar System and our galaxy, the Milky Way. History The history of astrometry is linked to the history of star catalogues, which gave astronomers reference points for objects in the sky so they could track their movements. In the 10th century, Abd al-Rahman al-Sufi carried out observations on the stars and described their positions, magnitudes and star color, and gave drawings for each constellation, in his Book of Fixed Stars. James Bradley first tried to measure stellar parallaxes in 1729. Applications Astronomers use astrometric techniques for the tracking of near-Earth objects.
First Planck results: the Universe is still weird and interesting Our current model of cosmology—the origin and structure of the whole Universe—has survived another major test, with the release of the first 15 months of data from the Planck mission. Planck is a European Space Agency mission, designed to study the cosmic microwave background (CMB), which preserves information about the conditions that persisted immediately after the Big Bang. Combined with results from prior experiments, Planck has revealed a Universe a little older than previously thought, and with a slightly different balance of ingredients. But amid these incremental changes, there was a bit of a surprise: despite the best hopes of researchers, Planck data does not rule out the existence of anomalous temperature fluctuations at large scales. Planck is a phenomenally sensitive instrument, kept at a 0.1° C above absolute zero by the use of liquid helium. That image helps tell us the Universe's age. Tiny fluctuations have big meanings The weird side of the CMB
Universal Formula for Cosmic Voids +Enlarge image N. Hamaus/Paris Inst. of Astrophys. & M. Warren/Los Alamos National Lab Most of the matter in the Universe consists of the mysterious dark matter, and cosmologists would like to better understand how it is organized in space. Scarcely anything is known about dark matter except that, apart from its gravitational effects, it hardly interacts with ordinary matter or light. Earlier simulations have shown that a uniform dark matter “gas” collapses under its own gravity into a tangled web of sheets and filaments that is permeated by relatively empty voids [1, 2]. Nico Hamaus of the Paris Institute of Astrophysics and his co-workers have now carried out simulations that probe the density profiles of dark matter voids in more detail than previous studies. Just as in previous studies, the dark matter clustered and created voids having a wide range of shapes and sizes. –Philip Ball References J.
Better Not Avoid A Cosmic Void (Inside Science) -- Sometimes nothingness can reveal a whole lot. While the universe is mostly empty, it contains bubble-like voids that are even emptier, taking up most of the space in the cosmos. And new research shows that these voids all look similar regardless of size — a consistency that may help unravel some of the universe's biggest mysteries. If you zoom way out, all the matter in the universe looks like a huge cobweb, consisting of an expansive network of filaments and wall-like structures that crisscross one another. More than 80 percent of this matter is dark matter, the invisible and mysterious stuff that appears to interact only gravitationally with the regular matter that makes up stars and galaxies. Residing in these filaments and walls of dark matter are galaxies, and the densest regions — where the filaments intersect — are sites of massive clusters of hundreds to thousands of galaxies. But between the filaments and walls of this cosmic web are vast cosmic voids.
3D Galactic Map May Solve Interstellar Puzzle Scientists have created the first 3D map of a type of astronomical interference that has puzzled astronomers for nearly a century. The new map could help scientists finally nail down the identity of the material that creates "diffuse interstellar bands" (DIBs) in observations of stars, the study authors said. The researchers focused on the single DIB 8620, one of over 400 absorption lines, with the goal of narrowing down its source. [Top 10 Star Mysteries] "DIB 8620 does not seem special compared to other DIBs," lead author Janez Kos, of the University of Ljubljana in Slovenia, told Space.com by email. However, as a spectral feature often used to measure stellar motion, it is "the most observed DIB." The result was the first large-scale map of DIB interference, and the first three-dimensional study of the DIB-bearing clouds in the interstellar medium. Some of the first proposed sources were molecules on dust grainsbetween stars, according to Kos.
From Quark to Quasar: The Observable Universe “That tiny dot that you can hardly make out in the screen is the Virgo Supercluster, where our galaxy, our local group and several others reside. All of those other dots are superclusters, each containing perhaps trillions of stars. Via WikiMedia If you really want a headache (the good kind), take a long look at this “photo”. You and I, and all the things we’ve ever known, are smack in the middle of this image, along with our Local group (which is a part of the larger Virgo Supercluster). Since the speed of light is a constant in the vacuum of space, from our location on Earth, there is an outer edge to what is we can see in the cosmos. It seems confusing, but there is a simple explanation: the universe has expanded in all directions since the big bang. This diagram shows how Earth’s observable universe compares to other places in space (Image via Nina) The “observable” universe is thought to consist of roughly: -*10 million superclusters - *25 billion galaxy groups The bombshell?
Cosmic Spider Swallows Starlight in Amazing Telescope View (Video, Photos) A dark, spider-shaped cloud of cosmic gas blocks out light from stars in a new image taken by a telescope in the Southern Hemisphere. The amazing photo, taken by a telescope at the European Southern Observatory's La Silla Observatory in Chile, is filled with stars glowing brightly in a variety of colors. Red, blue, yellow and orange stars frame the gas blob called Lupus 4, which blots out light from other, more distant stars in the center of the image. Eventually, Lupus 4, which is located about 400 light-years from Earth, could give birth to its own stars. A dark cloud of gas called Lupus 4 blocks out more-distant stars. "How many stars might eventually start to shine within Lupus 4? Another gas cloud in the same area, called Lupus 3, already hosts about 40 young stars that formed over the course of the last 3 million years, ESO said. Lupus 4 — a dark, spider-shaped cloud of gas — takes center stage in this wide view of the cloud located 400 light-years from Earth.
Welcome To Our New Galactic Supercluster Home: Laniakea | The Skeptics Guide to the Universe Your ultimate address just changed. Astronomers have discovered that the supercluster we’ve long-believed our Milky Galaxy resides in is actually just an appendage on the outskirts of an even more giant new supercluster called Laniakea. Every now and then we receive an email from someone who lists their address in a much more complete way than most everyone else does. Earth/Milky Way/Local Group/Virgo-Cluster/Virgo-SuperCluster/Visible Universe. We now know that this is wrong (and perhaps why inter-galactic email is so slow) The organization of matter in the visible universe can be thought of as a hierarchy of groupings of stars. Galaxies: These are the tightest gravitationally bound groups of stars forming various shapes such as ellipticals, spirals, irregulars etc. Galaxy Groups: Small collections (less than 50) of gravitationally bound galaxies. Clusters: These are structures consisting of galaxy groups and can consist of hundreds or thousands of galaxies. Even Bigger? Press Release