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On June 16, 1963 is a historic date for space and humanity: Valentina Tereshkova, 26, Soviet citizen, became the first woman cosmonaut in the world. A little over two years in another historic flight, Gagarin Juri on the morning of April 12, 1961 opened to man the path of space, the Russians scored another victory in the space race.

And this of Tereshkova is also a record destined to last over time, much more than his colleague Gagarin. It will be necessary to wait twenty years for another women to go into space. It’s another Soviet Svetlana Savitskaja in August 1982, who repeated the experience of Tereshkova.

However, as times have changed and means (the Russians have opened since 1971 the system of the “space train” and sent on many missions to space crews of three or more astronauts to occupy the space stations), Svetlana Savitskaya in “Soyuz T-7″ does not travel alone as Valentina Tereshkova in the “Vostok 6.” beside it are the commander Leonid Popov and engineer on board Alecsandro Serebrov.

This male presence made rivers of ink in newspapers around the world. Immediately after the trio of Russian space flight, word spread that Svetlana, in the name of science have been player of the first space love. The Russians repeatedly denied such an event, but in reality with little conviction.

Moreover, the first two cosmonauts histora know very little. Tereshkova is known comes from a humble family, which Adrian sedivorció Cosmonaut Nikolayev, who has a daughter and that after the historic flight he became a kind of myth in Russia. This is to the point, left space activity was devoted to politics with great success, going even part of the presidium of the Supreme Soviet.

Svetlana Savitskaya was, however, “daughter of specialists.” His father was Air Marshal Evgeni Savitskja, twice Hero of the Soviet Union by the merit of World War II, and as “like father like son,” Svetlana was playing with airplanes as a child rather than with dolls. His great passion was sky diving, to the point that at age 17 had already won three world records over 500 releases to his credit.

Unlike the Russian cosmonauts, Sally Ride, the first American on board the shuttle “Challenger” flew in space in June 1983, he knows everything or almost everything. Sally Ride was born in Encino, a suburb of Los Angeles bourgeois something nice, blue eyes and dark hair, 1.63 meters tall and 52 kg. weight. It looked like a girl who arrived by mistake in sterile world of the American space agency. But this is only in appearance. In fact, Sally always wanted to be an astronaut: “Since I was 12 or 13 years and was the time of the Mercury and Gemini spacecraft,” he says. “And so when I read in a newspaper of the University (Ride Sally graduated from Stanford with a thesis in astrophysics) that NASA astronauts seeking candidates for the” shuttle “, I dropped everything and rushed to introduce myself.”

Along with it were presented as shown in the archives of NASA, 8079 candidates, of whom 1544 were women. “All,” continued Sally, “I said I was crazy and asked me what my chances might be. But I was determined to achieve my objectives.”

From the time of Newton has been able to speculate about the origin of the Earth and solar system as a problem other than the creation of the universe as a whole. The idea was the solar system was a structure with a certain unified features:

1. – All major planets circling the Sun in approximately the plane of the solar Ecuador. In other words, if we prepare a three dimensional model of the Sun and its planets, we find that can be introduced into a shallow pan.

2. – All major planets revolve around the Sun in the same direction, counterclockwise to clockwise, if you look at the solar system from the North Star.

3. – All the major planets (except Uranus and possibly Venus) made one rotation around its axis in the same direction that its revolution around the Sun, or in contravention of the clock, also the sun moves in this regard.

4. – The planets are evenly spaced at increasing distances from the Sun and nearly circular orbits.

5. – All satellites, with very few exceptions, revolve around their planets in the planetary plane of Ecuador, and always in the opposite direction to clockwise. The regularity of such movements suggested, naturally, the intervention of some unique processes in the creation of the whole.
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The ancients, observing that the comet came and went unpredictably, surrounded by a pale mane and tail followed by an extremely changeable, had no doubts: it was something that had upset the celestial order.

The very fact that comets did not follow the movement of the planets, did nothing but strengthen this belief that led to regard comets as generally responsible for serious historical events. Thus, for centuries thought that comets were messengers of misfortune and the appearance of a comet was the cause of great concern in the villages.

In the first century BC JC. the writer Pliny attributed the cause of the bloody war between Julius Caesar and Pompey the passage of a comet. The same happened in many other occasions, also in 1066 when the Duke of Normandy William the Conqueror landed in England and killed King Harold II proclaimed the new king, was spotted another comet. Today we know that it was Halley’s comet, the most illustrious representative of this category of stars, returning periodically.

Leaving aside the superstitions, scientific opinion about the nature of comets, that our ancestors shared, that Aristotle was established about 350 a. JC. The great Greek philosopher formulated the theory that both comets and meteors were nothing to atmospheric phenomena caused by vapors in boiling fell off the Earth and were driven to the top of the atmosphere.

Aristotle’s conviction on the Comets survived for centuries and Galileo himself failed to solve the riddle of the paths of comets, though Tycho had almost total Lobras calculate accurately their enormous distances from Earth.

Only in the second half of the seventeenth century, thanks to the studies of Newton and Halley, it was possible to know that comets are influenced by the pull of the Sun but, unlike the planets follow highly elongated paths .

Halley calculated that the appearances of a comet in 1531 produced in 1607 and 1682, were due to the same celestial object and predicted that the comet would return in 1758. Halley did not live long enough to be able to see with their own eyes confirmed the prediction. The comet was submitted in time for the appointment and has since become known by name.

But we got to today. Until recently it was thought that comets were celestial bodies formed by cosmic debris, very similar to meteorites, wandering aimlessly through the solar system. Today, our knowledge of comets have undergone a revolution.

The American astronomer Fred Whipple has formulated a hypothesis that fits perfectly with most astronomical observations. According to Whipple, comets are like “dirty snowballs”, ie they would be formed by a conglomerate of ices (water, ammonia, carbon dioxide) and solid grains constituted of carbon and silicates.

And composite cores, due to its small size, lightweight and compact, they can resist the gravitational pull of the Sun and the planets, but ai the same time are quite volatile to justify ia huge cloud which surrounds the effect of solar heat. This hypothesis would also explain why comets are not visible because they lack the mane and tail.

According to the theory of Big Bang or Big Bang, generally accepted, the universe emerged from an initial explosion that caused the expansion of matter from a state of extreme condensation. However, in the original formulation of the theory of Big Bang there were several unresolved issues. The state of matter at the time of the explosion was such that he could not apply the normal physical laws. The degree of uniformity observed in the universe was also difficult to explain because, according to this theory, the universe would have expanded too quickly to develop this consistency.

The theory of Big Bang, the universe’s expansion is slowing, while inflation accelerates theory and induces detachment, ever faster, some objects from others. This separation speed becomes greater than the speed of light without violating relativity theory, which prohibits any body of finite mass moving faster than light. What happens is that the space around objects is expanding faster than light, while the bodies remain at rest relative to him.

This extraordinary rate of expansion is attributed to initial uniformity of the visible universe were the parts that were so close together, they had a common density and temperature.

H Alan Guth of the Massachusetts Institute of Technology (MIT) in 1981 suggested that the hot universe, in an intermediate stage, could expand exponentially. Guth’s idea postulated that this unfolding process of inflation while the primordial universe was in the unstable state of supercooling. This condition is common in supercooled phase transitions, for example in proper condition the water remains liquid below zero degrees. Of course, the supercooled water freezing ends, this event occurs at the end of inflation.

In 1982 the Russian cosmologist Andrei Linde introduced what is called “new inflationary universe hypothesis.” Linde realized that inflation is something that arises naturally in many theories of elementary particles, including the simplest models of scalar fields. If the majority of physicists have assumed that the universe was born once, that at first it was very hot, and the scalar field in the beginning had a minimum potential energy, then inflation appears as natural and necessary away from an exotic phenomenon appealed by the theorists to get out of trouble. This is a variant that does not require quantum gravitational effects, phase transitions, a supercooling or super heating also a first.

Considering all the possible types and values ​​of scalar fields in the primordial universe and trying to see if any of them leads to inflation, is that in places where it occurs, is kept small, and occurs in domains where end be exponentially large and dominate the total volume of the universe. Considering that scalar fields can take arbitrary values ​​in the primordial universe Andrei Linde called this scenario “chaotic inflation”.

Inflationary theory predicts that the universe must be essentially flat, which can be determined experimentally, since the density of matter in a flat universe is directly related to its rate of expansion.

The other testable prediction of this theory has to do with the density perturbations produced during inflation. These disturbances in the distribution of matter in the universe, which could even be accompanied by gravitational waves. The disturbances leave an imprint on the cosmic microwave background that fills the universe almost 15 billion years.

How does one become an astronaut? What requirements must be taken to be cast as the lead a mission in orbit, or even planet? It was difficult to answer these questions when NASA, in the now distant 1959, invited the U.S. Army to provide the first astronaut candidates. Lacked experience, without precedent: the only astronauts were described in science fiction books or strips Flash Gordon and Buck Rogers.

In the difficult search for the right men to be the first to go into space, NASA had in mind certain features essential to ensure their spatial ability: a technical degree, extensive experience as a pilot of military aircraft and a height not too high that allowed to enter the small cabin of the Mercury capsule. He scored more than 500 men who underwent psychological testing techniques and a specialized medical staff. Finally, many candidates were eliminated and others decided not to continue.

Those who survived were seven: M. Scott Carpenter, Gordon Cooper, Virgil Grissom, Donald Slayton, John Glenn, Walter Schirra, Alan Shepard. Each flew in a Mercury capsule, with the exception of Slayton that remained on the ground because no satisfactory cardiac conditions. However, Slayton was reinstated in 1975, participating in the Apollo-Soyuz.

This first batch of astronauts, of course, followed by others that NASA has selected the following years for programs Gemini, Apollo and Shuttle. Essentially, the requirements for the first astronauts have not changed until today, although for the Space Shuttle in particular, has lowered the age to thirty-five years. It is not essential to belong to the army, should not be restrictively high and low, new, women have been part of the selection of candidates for orbital missions.

However, the training program is as hard and exhausting as the first time. Essentially, when it is chosen to be an astronaut is like going back to school desks, despite the title already acquired, candidates must reexamine mathematics, meteorology, astronomy, physics, become familiar with computers and study space travel.

However, physical training is the hardest obstacle. To accustom to all the astronauts to weightlessness they will encounter in space, begins to train aboard a plane, a suitably modified C-135 inside, which artificially recreates the absence of gravity for periods longer than half a minute. During the moments of zero gravity, astronauts should practice various types of activity, handling equipment, food and drink. And it’s not easy training yourself to eat and drink in the absence of gravity.

In the days of John Glenn was obviated with a tube similar to toothpaste, which contained food were just paste. Instead, aboard the Shuttle, space technology allows a true miracle of rehydrated freeze-dried food at the time of consumption.

The training of the astronauts, it is obviously much more complex than hitherto described: For longer exercises in simulated conditions of weightlessness using a special pool where astronauts can train even with the model of the space shuttle. No missing after manipulations in the daily flight simulators and specialized courses with computers. And that information has taken an important role, as in many other aspects of our lives.

The first scientific measurement of a cosmic distance was made around the year 240 a. J. C. By Eratosthenes of Cyrene – director of the Library of Alexandria, by then the best scientific institution in the world – who appreciated the June 21, when the Sun at noon was exactly at its zenith in the city of Siena (Egypt), he was not also at the same time, in Alexandria, some 750 km north of Siena. Eratosthenes concluded that the explanation must be that the surface of the Earth being round, was ever farther from the sun at some points than others.

Building on the length of the shadow in Alexandria at noon on the solstice, the already advanced geometry could answer the question concerning the extent to which the surface of the Earth is curved in the journey of 750 km between Syene and Alexandria . From this value could be calculated the circumference and diameter of the Earth, assuming it had a spherical shape, a fact that Greek astronomers back then accepted without hesitation.

Eratosthenes made the corresponding calculations (in Greek units) and, as we can judge, their numbers were approximately 12,000 km for the diameter and 40,000 for the circumference of the Earth. Thus, although perhaps by chance, the calculation was quite correct. Unfortunately, this value did not prevail for the size of Earth. Approximately 100 years a. J. C, another Greek astronomer, Posidonius of Apamea, repeated experience of Eratosthenes, reaching the very different conclusion that the Earth had a circumference of approximately 29,000 km.

This smaller value was agreed that Ptolemy and therefore it was considered valid during medieval times. Columbus also accepted this figure and thus believed that a journey of 3,000 miles to the West would lead to Asia. If I had known the actual size of the land may not have ventured. Finally, in 1521-1523, Magellan’s fleet – or rather, the only ship left of it – first circumnavigated the Earth, allowing to restore the correct value, calculated by Eratosthenes. Read the rest of this entry »

Radio astronomy, an important branch of astronomy, study of celestial bodies through their emissions in the domain of radio waves.

In the late 1920′s, a young American engineer. Karl Jansky was working in Holmdel (New Jersey) in investigating the causes of radio interference from atmospheric sources involved with the long-distance transmission. Jansky built an antenna structure formed by a cage-metallica and suspended on the wheels of an old Ford, so that a motor turn the antenna in different directions. Then began a long and patient work of data collection, which consisted in recording the different types of radio noise captured at different wavelengths, but especially in the short waves and from various directions in the sky.

The results of this study indicated the existence of three types of interference: short download time from local time for downloads like distant, persistent wheezing from a mysterious source of regular movement across the sky.

After months of intense research Jansky came in the spring of 1932 concluded that the source of the noise was located in the constellation Sagittarius: in the direction of the nucleus of our Galaxy.

The news caused great excitement among the public and made many conjectures about the origin of those signals, however Jansky himself, who was an astronomer, realized that there was nothing mysterious about them realized that many celestial bodies, as well to radiate energy in the form of visible light, so do the form of radio waves.
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The Hubble Space Telescope is located at the outer edges of the atmosphere, in a circular orbit around the Earth about 593 km above sea level it takes to travel between 96 and 97 minutes. It was launched on April 24, 1990 as a joint project of NASA and ESA. The telescope can achieve optical resolutions greater than 0, the second of arc. It weighs around 11,000 kilos, is cylindrical and has a length of 13.2 m and a maximum diameter of 4.2 meters.

The reflector telescope and has two mirrors, with the main 2, 4 meters in diameter. To explore the sky incorporates several spectrometers and three cameras, a narrow field of view for shooting small areas of land (because of its remoteness faint glow), another wide field to produce images of planets and third infrared. By two solar panels generate electricity that powers the camera, the four engines used to orient and stabilize the telescope and the refrigeration of the infrared camera and spectrometer operating at -180 º C.

Since its launch, the telescope has received several visits from astronauts to correct various malfunctions and installing additional equipment. Friction with the atmosphere (very dim at that point), the telescope is losing weight very slowly, gaining speed, so each time it is visited, the space shuttle has to push a slightly higher orbit.

The advantage of having a telescope above the atmosphere lies mainly in that it absorbs certain wavelengths of electromagnetic radiation striking the Earth, especially in the infrared that obscures the images obtained, leading to poor quality and limiting the scope , or resolution, ground-based telescopes. In addition, they are also affected by meteorological factors (presence of clouds) and light pollution caused by the large urban settlements, which reduces the chances of ground-based telescopes location.

Since it was launched into orbit in 1990 to avoid distortion of the atmosphere – historically, the problem of all ground-based telescopes – Hubble has enabled scientists to see the universe with a clarity never achieved. In their observations, the astronomers confirmed the existence of black holes, clarified ideas about the birth of the universe in a huge explosion, the Big Bang occurred about 13,700 million years, and revealed new galaxies and systems in the far corners of cosmos. Hubble scientists also helped to establish that the solar system is much younger than the universe.

At first it was thought to bring the telescope back to Earth every five years for maintenance, and also have a peacekeeping mission in space in each period. Later, seeing the complications and risks involved return the instrument to Earth and re-launch, it was decided that there would be a peacekeeping mission in space three years, being the first one scheduled for December 1993. When shortly after being launched, it was discovered that Hubble was suffering from an aberration due to an error in construction, officials began counting the days for the first servicing mission, hoping that the error could be corrected optics.

Starting in the first servicing mission system was installed to correct the telescope’s optics, sacrificing for this instrument (the fast photometer), the Hubble has proven to be an instrument without equal, capable of affecting observations continuously our ideas about the universe.

Hubble provided dramatic images of the collision of comet Shoemaker-Levy 9 with Jupiter in 1994 as well as evidence of the existence of planets orbiting other stars. Some of the observations that led to the current model of the expanding universe with this telescope were obtained. The theory that most galaxies host a black hole at its core has been partially confirmed by numerous observations.

In December 1995, the telescope photographed the Hubble Deep Field, a region the size of a thirty-millionth the area of ​​sky that contains several thousand galaxies. A similar picture was taken in the southern hemisphere in 1998 to appreciate significant similarities between the two, which has reinforced the principle that posits that the structure of the universe is independent of the direction in which you look.

The Big Bang, big bang literally, is the moment of “nothingness” emerge all matter, ie the origin of the universe. Matter, so far, is a point of infinite density, which at one time “explodes” generating the expansion of matter in all directions and creating what we know as our Universe.

Immediately after the time of “explosion” every particle of matter began to move very quickly from one another in the same manner that inflate a balloon it is occupying more space to expand its surface. Theoretical physicists have managed to reconstruct the chronology of events from a 1 / 100 second after the Big Bang. The material released in all directions on the primordial explosion consist exclusively of elementary particles: electrons, positrons, Inns, baryons, neutrinos, photons and so on up to more than 89 particles known today.

In 1948 the Russian physicist George Gamow modified U.S. citizen of Lemaître’s theory of the primordial nucleus. Gamow proposed that the universe was created in a gigantic explosion and that the various elements observed today were produced during the first minutes after the Big Bang or Big Bang, when the extremely high temperature and density of the universe merged subatomic particles in the chemical elements.

More recent calculations indicate that hydrogen and helium would have been the primary products of the Big Bang, and the heavier elements were produced later within stars. However, Gamow’s theory provides a basis for understanding the early stages of the Universe and its subsequent evolution. Because of its very high density of matter existing in the early Universe expanded rapidly. As it expanded, helium and hydrogen is cooled and condensed into stars and galaxies. This explains the expansion of the universe and the physical basis of Hubble’s law.

As the universe expanded, the residual radiation from the Big Bang continued to cool, until a temperature of about 3 K (-270 ° C). These vestiges of the microwave background radiation were detected by radio astronomers in 1965, providing what most astronomers consider confirmation of the theory of Big Bang.

One of the unsolved problems in the model of expanding universe is if the universe is open or closed (ie, whether it will expand forever or will collapse).

An attempt to solve this problem is to determine if the average density of matter in the universe is greater than the critical value in the Friedmann model. The mass of a galaxy can be measured by observing the motion of their stars, multiplying the mass of each galaxy by the number of galaxies is that the density is only 5 to 10% of critical value. The mass of a galaxy cluster can be determined similarly, by measuring the motion of galaxies it contains. Multiplying this mass by the number of clusters of galaxies we obtain a much higher density, approaching the critical limit indicating that the universe is closed.

The difference between these two methods suggests the presence of invisible matter, called dark matter within each cluster but outside the visible galaxies. Until you understand the phenomenon of hidden mass, this method of determining the fate of the universe is unconvincing.

Many of the regular work in theoretical cosmology is focused on developing a better understanding of the processes that must have led to the Big Bang. The inflationary theory, formulated in the 1980s, Solves Big Gamow’s original approach by incorporating recent advances in the physics of elementary particles. These theories have also led to speculation as bold as the possibility of an infinity of universes produced according to the inflationary model.

However, most cosmologists are concerned over the whereabouts of the dark matter, while a minority led by the Swede Hannes Alfvén, Nobel Laureate in Physics, held the idea that not only gravity but also the phenomena plasma, are the key to understanding the structure and evolution of the Universe.

According to the laws of motion first established in detail by Isaac Newton in 1680-89, two or more movements are added according to the rules of arithmetic. Suppose a train passes by us at 20 mph and a child throws a ball off the train at 20 miles per hour in the direction of motion of the train. For the child who moves with the train, the ball moves at 20 miles per hour. But for us train movement and the ball are added, so the ball will move at the speed of 40 miles per hour.

As you see, can not speak of the speed of the ball to dry. What counts is its speed relative to a particular observer. Any theory of movement attempts to explain how the speed (and related phenomena) seem to vary from one observer to another would be a “theory of relativity.”

The theory of relativity Einstein was born the following fact: what works for balls thrown from a train does not work for light. In principle it could be that the light spread, or for the earth’s motion or against it. In the first case would seem to travel faster than the second (the same way that a plane travels faster in relation to the ground when you carry a tailwind as when it is facing). However, very careful measurements showed that the speed of light never varies, whatever the nature of the motion of the source emitting the light.

Einstein then said, suppose that when measuring the speed of light in vacuum, it is always the same value (about 299,793 miles per second) in all circumstances. How can we have the laws of the universe to explain this? Einstein found that to explain the constancy of the speed of light had to accept a series of unexpected events.

He found that objects had to be shortened in the direction of movement, especially as most were its speed, and finally to zero in a length limit of the speed of light the mass of moving objects had to increase with speed to be infinite in the limit of the speed of light, that over time a moving object was getting slower with increasing speed, up to stop at this limit, the mass was equivalent to a certain amount of energy and vice versa.

All this developed in 1905 in the form of the “special theory of relativity”, which dealt with a constant velocity of bodies. In 1915 drew even more subtle consequences for objects with variable speed, including a description of the behavior of gravitational effects. It was the “general theory of relativity.”

The changes predicted by Einstein are only noticeable at high speeds. Such speeds have been observed between the subatomic particles, finding that the changes were predicted by Einstein really, and with great accuracy. Moreover, if the theory of relativity Einstein was wrong, particle accelerators could not function, atomic bombs would not explode and certain astronomical observations impossible to do.

But running speeds, the predicted changes are small enough to be ignored. In these circumstances governing the numeracy of Newton’s laws, and as we are accustomed to the operation of these laws, we now seem “common sense”, whereas Einstein’s law seems to us “weird.”