Cervix Is Hard And Open

Chasing a comet to decipher our origins The dark galaxy clusters

We had to wait until 1800 and the fortuitous discovery of some 800 kg of grain to be able to translate Egyptian hieroglyphics. The "Rosetta Stone" is a sheet that contains the same text in Egyptian and greek, which allowed, thanks to the knowledge of greek, to decipher the hieroglyphs today and give us the knowledge of a language that would otherwise have remained forever immersed in the mystery .

Similarly, the Rosetta mission is now on the road to get to decipher his "subscriptions" testifying to the origins of our solar system. This time, however, rather than wait for the emergence of some random dusty archaeological site, the tracks that we are hiding on some of the most remote bodies in our solar system: modern sites archaeological anything but dusty. Comets and asteroids , in fact, may be regarded as cocoons remaining from the formation of our solar system and therefore represent the best places where to go in search of our subscriptions.

During the time of the formation of the Solar System (more than 4 billion years ago) a huge disk of dust swirling around an embryo of our Sun has begun to thicken, creating a body size gradually more significant. The largest, called planetoids, have also begun to have a "life" and geological own gravity, while the smaller bodies have not reached sufficient size to attract more dust. Formed in the outer regions of the solar system, so cold that many of the materials of the disk of dust, including water, were in solid form, have preserved some of their chemical structure without undergoing significant changes later.

Some of the bodies in question are now comets: piles of rock and ice above that move around the Sun in highly elliptical orbits. This allows them to experience completely different conditions and environments, from extremely dark and cold regions, far beyond the outermost planets, to areas where the solar influence is so strong, both in terms of gravity and heat, to change radically their structure Physico-chemistry, giving the other hand the superb foliage. To find and use our new stele we have to reach and explore a comet before its first approach to the Sun, "guilty" to completely erase the evidence of which we are looking for.

Rosetta, whose name is directly borrowed from the famous stele of the above was launched by European Space Agency (ESA) in 2004 and has as its primary objective the comet 67P/Churyumov-Gerasimenko. After almost five years Rosetta is about half way of his trip, which ends in 2014 beyond the orbit of Jupiter, 10 years after the launch and in conditions such that you can begin to turn around the comet rather than just pass by.

To read our stele and to take advantage of the long journey made, the probe carries with it Philae, a small robot (the one which is labeled a "lander") that will be issued by Rosetta very slowly to land on the comet. The severity of 67P, however, is so low (we're talking about a "mass" of about 4 km in diameter) that some drills and cables will be necessary so that the lander on the comet does not rebound and lost in interplanetary space.

reach a comet is a journey much more detail than the "standard" which is taken to reach a planet. The severity each of the massive bodies of the Solar System can be used to modify the initial orbit to reach a moderate spending more energy from the Earth in an orbit with a very low cost of fuel or, at worst, nothing at all. The trick is to 'steal' a bit of gravitational energy of the planet passing very near. The planet, infinitely more massive than our Rosetta, will not notice anything, the probe, however, receive a significant boost that will accelerate to its destination.

Road Rosetta has three gravitational encounters with the Earth and a Mars before he could reach the comet 67P and put into orbit around it so that it can be follow for a while on her way to the sun The last step of the probe close to the Earth occurred on November 13, 2009: we have seen, therefore, the last chance for us to see close to Rosetta and her a closer look at an inhabited planet. During his journey Rosetta has already visited, in September 2008, including the asteroid 2867 Steins, the next step in his short tour of small bodies in the solar system will, in about a year, the flyby with the asteroid Leutelia , another small step important for our search for clues about the origins of the Solar System.

Then the probe will be "off", or put in what is called a state of hibernation in which only a faint beep from his main computer will continue to reach Earth. Hibernation, planned to save energy during the coldest part of his trip will last for four years to make operational all the equipment back on board near the comet. Only then will again be switched on his instruments for our final assault to the hieroglyphics that still hide our origins.

Pierpaolo Pergola

Pictured from top to bottom: the Rosetta stone, dating from the second century BC and exhibited at the British Museum in London, a representation of the encounter between the Rosetta space probe and the comet 67P/Churyumov-Gerasimenko, what will happen in 2014, the complex trajectory of the Rosetta probe through the orbits of various solar system bodies.

Angela's Moncler Cost

The galaxies in the universe tend to stay together : astronomers noticed it already in the thirties, analyzing photographic plates made at the time that those were the most powerful observatories the world. Recognize the "clusters" of galaxies in an image in two dimensions is not trivial: often, two or more neighboring galaxies appear only for an effect of projection, which makes them fall into the same point of time Heavenly although in reality very far from each other. In other cases, however, it is physically nearby galaxies, one o'clock that feel the gravitational pull of the other: depending on the number of objects involved, astronomers speak of groups (a few dozen) or clusters (up to some thousand) of galaxies.

The clusters of galaxies are the largest structures in the universe, to be held together by gravity. They extend up to tens of millions of light years and have a mass of up to a few million billion times the Sun Yet this mass of galaxies accounts for less than ten percent! Astronomers continue to call them clusters galaxies for historical reasons, but as it turned out later, the main components of these giants are the cosmic gas, hot mixture of electrons and protons at a temperature of at least ten million degrees, emitting X-rays, and dark matter , which does not emit light and therefore can not be observed, but whose presence can be intuited indirectly.

isolate the contributions due to galaxies and gas is relatively simple: the first can be observed with conventional optical telescopes, the second thanks to satellites that operate in the band X-ray The dark matter, however, represents a sensitive subject and, in some circles, still controversial. The total mass

of a cluster can be studied by the effect of gravitational lensing, gravitational lensing or that it exerts on galaxies, located "behind" the cluster: their shape is distorted in a characteristic way, described by the theory of Einstein's general relativity, which depends on the total amount of matter contained in the cluster. Many astrophysicists, but not all, believe that the clusters are dominated by this elusive dark matter, and attach it to the total mass reconstructed by gravitational lensing.


In 2006, a very particular object has shed light on these obscure topics: "Bullet Cluster" (English, Bullet Cluster). This is actually two clusters that have "recently" clash "the cloud" of gas in the cluster on the right (the bullet) does have the typical form of a shock wave, shaped by the collision with the other . The gas has slowed down during the clash, a sort of "friction" that is separated from the galaxies from regions where it is saved most of the two clusters of matter as it was "discovered" by the study of lensing gravity. This separation shows that most of the material has interacted with the gas only via gravity. The appearance of these "scrap" cosmic is thus interpreted as evidence of the existence of dark matter.

CLAUDIA MIGNONE

In this image of the "Bullet Cluster observations of galaxies (white / yellow) and gas (pink) are coupled with the reconstruction of the mass is brought about by gravitational lensing (in blue). Image NASA / CXC / CfA / M.Markevitch et al. (Observations X) NASA / STScI, Magellan / U.Arizona / D.Clowe et al. (Optical observations), NASA / STScI, ESO WFI, Magellan / U.Arizona / D.Clowe et al. (Reconstruction by lensing).

Collapse Puzzle Hacks

All eyes on the Milky Way

Anyone admired the night sky will perhaps surprising to believe that our eyes are really blind than most of the "light" which comes from the universe. What we perceive is, in fact, only a small fraction of the energy that stars, galaxies and other astronomical sources produce.

The so-called light "visible" is but a fraction of what scientists call the "electromagnetic spectrum: radio waves, microwaves, infrared light correspond to lower energies than visible light, ultraviolet light, X rays and rays range rather have higher energies, but it's still light. The atmosphere

Earth, also contributes to our "isolation" taking some of this radiation and allowing only visible light and radio waves. If there were no atmosphere, and if our eyes have evolved in some of the countless other ways, probably the night sky would appear in a different way.

Thanks to technological advances of recent decades, astronomers have learned to look at the sky but also in other energy, thus creating innumerable discoveries. Using space telescopes that scan the universe from a privileged location outside the atmosphere, in orbit around the Earth, have been able to open "new eyes" on cosmos, observed by light infrared and ultraviolet, through X-rays, gamma rays and microwave .

In particular, the images of the same object made of different "bands" of energy reveal the wide range of physical phenomena that occur within it. This image, released last Tuesday by NASA, it is a shining example.


For being portrayed is the center of our galaxy, the Milky Way, which is hidden inside a supermassive black hole with a mass equal to four million times that of the Sun, whose presence you can not directly observe only sense in an indirect way. The different colors in the image correspond to observations made in different energy bands, and reflect different physical phenomena.

what he sees Hubble Space Telescope in visible light and the so-called "near-infrared, is shown in yellow: it is hundreds of thousands of stars, some of which are emerging while others shine, burning the their nuclear fuel. In red, however, shows the observations made by the infrared Spitzer Space Telescope. The infrared light corresponds to lower energies than visible objects Spitzer is so sensitive to colder than to Hubble, and can "see" the filamentary structure of the clouds of cosmic dust , forged by winds generated by nearby stars, and from which new stars are born in the future. Blue and purple, finally, to the observed data are reproduced by the Space Telescope Chandra X-ray: X-rays are emitted by gas at very high temperatures, over a million degrees, which is located near the galactic center, so warm thanks to 'energy released from the nearby stellar explosions and energy jets from the black hole hidden in the heart of the Milky Way.

combining the images obtained with different telescopes, astronomers have been able to discover previously unknown details about the phenomena violent and impetuous that take place in the center of our Galaxy, about 26.000 years-light from us.

CLAUDIA MIGNONE

This image, about the size of the full moon in the sky, shows the rising stars, explosions, clouds of gas and dust in the Milky Way's center. The different colors correspond to observations in different bands of the electromagnetic spectrum: the yellow is in the visible and near infrared observations (Hubble), red is infrared observations (Spitzer), the blue-violet shows the X-ray observations (Chandra). Image released by NASA, ESA, CXC, SSC, STScI.

Homemade Aluminium Boats

The energy gamma rays

All amateur astronomers are accustomed to seeing images of the same object in different energy bands from radio observations, optical, infrared, ultraviolet, X-ray It is not so common, however, hear about most of the energy of the electromagnetic spectrum: gamma rays.

This light has an energy about 10 billion times greater than the light to which the human eye is sensitive. Unfortunately it is not possible to directly observe this radiation as the Earth's atmosphere is not transparent at these energies. The problem can be circumvented in part through the use of space telescopes , but what about an important part of gamma rays, high energy ones, this is not possible for purely logistical reasons: these photons are so rare that the dimensions of the telescope are prohibitive for an experiment to be sent into orbit.

Another way to observe these photons uses the same atmosphere of the Earth as a large particle detector. The gamma rays that pass through the atmosphere interact with the atoms thereof and lose energy, producing a cascade of particles. The particles in the cascade have a speed faster than the speed of light in the atmosphere (but still less than the speed of light in vacuum!) And produce the so-called Cherenkov radiation: this is a cone of light that, when it reaches the ground, it can illuminate an area of \u200b\u200babout 100 meters range!

This light is then gathered by telescopes and analyzed. Among the latest experiments in this field include HESS (High Energy Stereoscopic System), located in Namibia, MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov Telescope), located in La Palma, Canary Islands, and VERITAS (Very Energetic Radiation Imaging Telescope Array System), Arizona, United States. These experiments take advantage of the stereoscopic technique, or use multiple telescopes spread over an extensive area, to cover the cone of light produced by the waterfall: this allows us to determine more certainty the direction from which the photons and their energy.


Each telescope is not fundamentally different from a traditional optical telescope. The main difference is the size of the mirror: the two telescopes MAGIC experiment, for example, have a diameter of about 17 meters each, while that of the telescope to be built during the next phase of the experiment HESS is even over 20 meters ! Of course it is not monolithic mirrors, which consist of a single block, but made up of many small pieces.

Many and various are the astronomical objects that can be studied with this technique: an example is jets of particles emitted by the nuclei of so-called active galaxies, which hide within them a supermassive black hole that devours the surrounding matter, or nebulae of energetic particles ejected from the stars when, at the end of their lives, explode in the form of supernovae.

GIOVANNA PEDALETTI

picture, the four telescopes currently comprising the HESS experiment in the Plateau of Khomas, Namibia. The experiment is fully operational since 2004, will be enhanced in the coming years with more telescopes to achieve even better performance. (Credits: HESS Collaboration)