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Saturday, 17 January 2015

The Solar System And Planets


The solar system is, so to say, our "neighborhood" in space. The Earth, which is our home, orbiting the Sun making a revolution, ie a round, per year. Together with eight other major planets orbit the Earth, two closest to the Sun, the other more distant. Besides these there are dozens of moons that orbit the planets, and thousands of minor bodies, such as asteroids and comets.

The Sun is the body by far the largest of the system and that's what, with its heat, warms everyone else, that the orbit. This set of bodies is the Solar System and has originated from the same cloud about 5 billion years ago. We will see together some slides of the main bodies of the system, imagining a journey from the Sun to the suburbs. Most of the images that we will have been taken from scientific satellites with on-board special cameras that can work in the space, at temperatures and prohibitive conditions. 

Sun:

We perceive the sunlight and see sometimes it’s hard to sunset or behind a blanket of clouds. The light that warms us takes less than 8 minutes to get to us which means - at about 300,000 kilometers per second, which is the speed of light - that the Sun is approximately 149.5 million kilometers away from us, or 1 astronomical unit (UA). The diameter of the Sun is about 1.4 million kilometers.

The energy produced by the core a little at a time, By committing about a hundred thousand years since it was first produced (in a vacuum would take 2 seconds), comes out on the surface of the sun, that the photosphere, where there are about 6000 degrees, and then takes eight minutes to get to the Earth through the short layer of the chromosphere and then the crown, an immense cloud of plasma that surrounds the entire Sun and that fades slowly in space.

As you can see from the pictures, the Sun is not a quiet place to spend the weekend. From Earth, with our telescopes properly filtered can see various phenomena, such as sunspots. These in particular are areas where the magnetic field becomes so intense that blocks the warm currents which rise from below to warm the surface, and then the areas appear darker because slightly colder (we talk of less than one thousand degrees less of about six thousand degrees). The warm currents that peek on the surface appear as grains: why the Sun through a telescope looks wrinkled like the skin of an orange.

Mercury 

If the Sun were great an inch, and the Earth far it was 1 meter (then 1UA = 1m), the first planet that would meet, at 39 cm, would be Mercury. As you can see from the pictures, this planet looks a little like our Moon. The diameter of Mercury is 4878 km, and less than half of the Earth. The filming of the probe Mariner 10, which was the first to approach the planet, in 1973, have now been replaced by those of the probe Messenger. There are craters, like the Moon, and flat surfaces.

The day, which is the period of the day when there is the Sun, Earth lasts 176 days with temperatures around 400 ° C
Mercury has no seasons, and then the Sun, during the year, it is always at the same height. There are craters that never see the sun, and are thus always extremely cold temperatures. Some surveys conducted with radio telescopes would have shown the characteristics of ice reflections.

Venus

So get away from Mercury and 72 cm from the Sun (0.72 AU) meet Venus, the second planet of the Solar System and the one whose orbit is closest to Earth. It is often seen at dusk or dawn, and appears very bright.

It has the same size as Earth, and probably a time Earth and Venus were similar. The development, however, was completely different. The temperature of Venus is 460 ° C, so that the rocks appear luminescent. The climate is dominated by a very effective greenhouse, because the large amount of CO2 traps heat from the Sun (Mercury, where there is no atmosphere, the heat escapes at night).
 There is no free water, and there is a ground pressure of about 90 atmospheres.

Earth

As you know well, however, a few feet from our Sun (1 AU) is the planet with a very large satellite: the Moon. The Earth seen from space is very nice, but at night you see so many unnecessary lights that waste energy and resources and pollute so much: it is the phenomenon of 'light pollution.

Mars

At 152 cm from the Sun (1,52UA) is the red planet, Mars, which is visible to the naked eye. It has an equatorial diameter of 6786 km (the Earth has 12,700) and has polar caps where there is strong evidence of the presence of water ice.

Many pictures taken from various probes showed some real rivers dry, a sign that the planet was once liquid water, essential for life. No atmosphere, although it is much more tenuous than the Earth: the pressure is only 6 thousandths of atmosphere (about 6 milli bars). There are many craters, valleys and plains, and there is also the largest volcano in the solar system: Olympus Mons.

Jupiter

At 5.2 meters from the Sun (5.2 AU) meet the first gaseous planet, ie on the surface you cannot walk. This is Jupiter, who observed with a small telescope shows its stripes and its major satellites, discovered by the great Italian astronomer Galileo Galilei.

Jupiter than Earth, is huge: it has an equatorial diameter of 143,000 kilometers, compared to 12,700 of the Earth. Its atmosphere has bands of clouds and stains, and is composed of methane, ammonia, H, He, C, N.

Emits three times more heat than it receives from the Sun, thus helping to warm its satellites, which are very interesting and we will see quickly. Jupiter, like all gas giants, presents a ring, not visible to the naked eye even with larger telescopes, but resumed by interplanetary probes that have studied.

Saturn

At 9.5 meters from the Sun is Saturn, the second planet by diameter. With a small telescope you can see its rings and its moon main, Titan. And 'the farthest planets easily visible to the naked eye, and 'the second, also by distance from the Sun, the four gas giants, and has an atmosphere composed principal men ballet hydrogen (H) and helium (He). Takes 29.5 years to complete one revolution around the sun. The atmosphere resembles that of Jupiter.

Saturn is most famous for its spectacular rings which are inclined at 28 ° to the orbit and are structured in different groups. Are very thin: with a diameter of 250,000 kilometers have thickness of only 1 km.

Uranus

And 'the seventh planet, another gas giant, visible with a little' difficulty to the naked eye, but easily observed with a small telescope. It was discovered in 1781 by William Herschel. And 'far, more than twice the distance of Saturn: 19.2 UA. E 'was only visited by Voyager 2 in January 1986.

 The planet "roll" along its orbit, as the axis of rotation is perpendicular to the revolution. This is due to a collision with a great body at the dawn of the Solar System. The orbital period is 84 years. Have very thin rings, which were discovered from the ground.

Neptune

It was discovered in 1846 and visited by Voyager 2 in 1989. The engineers struggled with the lack of available light for the filming of its surface, but eventually got the beautiful images. It 'a gas giant and has 4 rings and 8 satellites. It is located at 30.1 AU.

Pluto (134340) (dwarf planet)

Was only discovered in 1930 by Charles Tombaught and for 76 years has been considered the ninth planet in the solar system. On 25 August 2006, during the IAU Congress 2006 in Prague, the IAU-International Astronomical Union redefined the parameters for the identification of the planets and was introduced the new class of objects called "dwarf planets" (dwarf planets), in which were included the former asteroid Ceres, Pluto, Eris (2003 UB313) and perhaps others in the future.

Later he was assigned an identification also asteroid; its catalog number becomes therefore 134340.

Pluto is located at an average distance of 39.5 AU from the Sun and has a satellite half the size of the planet, Charon, 1,100 km in diameter. Not much is known of this body, which was until 2006 the smallest and most distant of the planets has a diameter of 2200 km and only the Hubble Space Telescope has allowed mapping course. And 'the only object over 2000 kilometers in diameter to be not yet been visited by a space mission.

Radioactivity

Radioactivity

Radioactivity is the phenomenon whereby some nuclei, not stable, are transformed into other emitting particles. Radioactivity was not invented by man, but on the contrary, man is exposed to radioactivity from the moment of its appearance on Earth. The radioactivity is as old as the universe and is present everywhere: in the Stars, in the Earth even in our own bodies.

The discovery of radioactivity occurred to the 800 by Henry Becquerel and Marie Curie spouses, who received the Nobel Prize for Physics for their research. They discovered that some minerals, uranium and radio, had the property of impressing photographic plates placed in their vicinity. Photographic plates, once developed, had dark spots.

Elements such as uranium, radium and polonium were referred to as "active" and the phenomenon of particle emission was told radioactivity. They have since been identified nearly 2,500 species of different nuclei, and only a small percentage of them, about 280, are stable.

Origin of Radioactivity

Radioactive isotopes can be natural or artificial origin. However one must not think that the natural radioactivity and artificial phenomena are different, since the physical process at the base is the same for both.

The natural radioisotopes have originated at the center of the stars, through nuclear reactions or during the explosions of supernovae. Some of these nuclei, such as potassium-40 (40K), thorium-232 (232Th) and uranium-235/238 (235U / 238U) are still active, as their half-life is several billion of years. The measurement of the abundance of these isotopes remaining on Earth can be traced back to the age of our planet, which is calculated in 4.5 billion years.

The artificial radioactive nuclei were created in the laboratory or in nuclear reactors.

The Radioactivity In Nature

The radioactivity is a natural phenomenon: for this reason anything on Earth, including our bodies, contains a certain percentage of radioactive elements.

The radioactivity in the air is due to the presence of radon (Rn). This element is produced by the decay of uranium and thorium, which are found in many materials, especially in the rocks. As gas, radon is able to "evaporate" spreading in the air. In 1,3 of air in a closed building occur on an average 30 radon 

Chemical Bonds

Chemical-bonds

Formation of chemical bonds

With the term chemical bond is globally indicate interactions between atoms that lead to formation of molecules or even to the formation of ionic crystals or crystals of metallic type. These interactions are mainly the outer electrons of atoms and produce changes in the electronic structure of atoms.

The fundamentals of electronic theory of the chemical bond are based on the model of GN Lewis that the binding affects only the outer electrons of atoms: each atom tends to complete the orbital of the outermost level (and therefore to have eight valence electrons) is taking or giving electrons, is putting electrons in common. But a satisfactory understanding of the nature of the chemical bonds is achieved only with hypotheses that take account of quantum mechanics: these theories originated by two distinct approaches, the method of valence bond and molecular orbital method.
Classification of the chemical bonds

Types of chemical bonds:

1 Covalent bond

The covalent bond is formed between atoms that have a high value of electro negativity between atoms and therefore "non-metallic". There are two types of covalent bond: the covalent bond and the pure polar covalent bond.

The pure covalent bond (covalent or homopolar) occurs between atoms of the same element.

The polar covalent bond (covalent or heteropolar) occurs between atoms of different elements (but 
the two atoms must have a difference of electro negativity of less than 1.9).

In reality, there is also a special type of covalent bond called dative bond in which an atom donor or said employer provides the pair of bonding electrons. This pair of electrons is shared with an atom acceptor said. This bond once formed is not distinguishable from a normal covalent bond.

2 Ionic Bond

Ionic bonding is achieved when the difference in electro negativity between the two elements that intend to bind is greater than 1.9. Occur the transfer of one or more electrons from the less electronegative atom more electronegative. The metallic bond holds together the atoms of a metal.


Surface Of The Moon

Surface-of-moon

The Moon has a spherical shape as a whole, but the irregularities which should define the exact shape of solenoid (the equivalent of the geoids for the Earth) are still being studied, using satellites Lunar Orbiter that reveal changes in gravity and density in various parts.

It is also observed with the naked eye the Moon has some large dark spots.

A small telescope is sufficient to highlight the features of the lunar landscape. The `` sea '' are of great extensions of rocks similar to basalt. The ancients did not have them watched and Galileo was the first to reveal them by giving them special names with Serenitatis, Nectaris etc.

 The seas are virtually absent hemisphere invisible to us, as revealed probes. The `` amphitheaters or circuses '' are circular depressions with diameters measuring from just over 200km telescopic and are surrounded by ramparts generally steeper toward the inside, are numerous, so that the surface of the Moon appears pitted, as devastated by a terrible bombing. In total these circuses would be about 30,000 and often in a circus is an isolated peak. 

The `` crater '' are much more numerous circuses and much larger than the terrestrial ones: in fact, the largest terrestrial crater measuring 5km in diameter, while the moon there are some with a diameter of at least 150km. These craters, unlike the circuses that are low on the lunar surface, may be located at a height of 2000m and beyond.

Since the moon is not possible to refer to a zero level (such as the sea level here on Earth), was taken as the base point for all measurements, the horizontal and vertical bottom of the crater Molesting 

A, which is located almost in center of the hemisphere visible and to which cartographers have assigned a height difference of 7km from the edge. It can be said that there are around the moon it atmosphere or water since the mountains are not weathering and during eclipses do not have the slightest deformation of the outline of the moon. The temperature of the Moon is excessive: it presents the maximum and minimum 120gc -150gC.

The color of the moon can be said that the name of "silver disc" is wrong because its color tending to pale yellow. The color is not uniform, due to the irregularities of the surface and the interaction with the Earth: it is said that the light came from the Sun to Earth, is reflected by this on the moon, in turn, reflected towards the Earth. This light is very weak, because for the Earth, the relationship between the amounts of light receives from the Sun and the one that it reflects is 0.45 and the ratio analogous to the Moon is 0:07. Because the Moon can be faintly visible even during the new moon.

The crescent Moon has a higher brightness to the average, and this makes it look bigger. At the Observatory has detected that the Earthshine is greater when the "solar wind" is richer than protons; it is therefore a phenomenon of luminescence similar to that which some chemicals present when certain chemicals are affected by ultraviolet or X. Another typical conformation of the Moon rays are the, thin streaks of clear powder, which depart as rays, from the craters larger and younger; it is thought that they are formed due to the impact of meteorites that crushing rocks. The entire lunar surface is covered with debris, caused by weathering, but certainly not from the degradation of space, that is, by the continuous abrasion caused by meteorites.

Amoeba

Amoeba
Amoebas are living rhizopods consisting of a single cell that is mobile. Amoebae live in wetlands and can enter the human body through drinking water or contaminated food outlet. A species of amoeba called entamoeba histolytic is responsible of a disease called amebiasis.

After localized in the colon, the amoeba can be involved in dysentery with often painful and possibly bloody diarrhea associated with abdominal pain. It can then colonize other organs including the lungs, the brain or the liver more frequently taking it up in the form of abscesses.


Given these digestive symptoms or discovery of abscess imaging tests, confirmation of the parasitic infection is done on a blood sample, and so-called amoebic ides drugs can treat it.