Saturday, June 18, 2011

THE SOLAR SYSTEM AND PLANETS


The solar system consists of a star is the sun, 9 planets in order of distance from the Sun are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.
Elliptical orbit between Mars and Jupiter are planets and asteroids, along with some 1800 satellites.
They are also a few thousand comets, which are bodies formed mainly of rocks and ice. Since their orbits very squashed, passing near the Sun sublimates the ice, giving rise to the wake. For each round until a comet then you consume to lose a few pieces of rock that can be attracted to nearby planets or bodies, giving rise to the phenomenon of meteorites.
These blocks are called meteors if you consume through the atmosphere of planets and meteorites but if it come to the surface.
The study of meteorites allows us to study different materials.
The solar system was formed about 4.6 billion years ago to the collapse of a nebula, which is an area where there are gas and dust (interstellar matter) which take particular values ​​of pressure, temperature and density.
Some nebulae are expanding, others are in a state of balance and still others are collapsing. In these stars form.
In the solar system is part of the Milky Way Galaxy and other galaxies together to give life to the Universe. Galaxies take many forms, the Milky Way has a spiral shape with a central galactic nucleus, from which two main and two shorter arms.
The solar system is about 27000 years the light from the nucleus of one of the longest arms, that of Orion, the other is that of Perseus.

The solar system makes a movement of revolution around the nucleus, a transversal, towards the constellation of Hercules and a recession that affects the motion of the galaxy.
The units of measurement are used to evaluate the astronomical distances are:
the astronomical unit (au) to calculate distances within the Solar system and serves as the average distance between the sun and the earth that is 149600000 km;
the light-year (until) that is used to measure distances between stars and goes as the distance light travels in one year;
PARSEK worth the 3.26 light years, and is used to calculate distances.



THE SUN
The sun has a structure common to many stars. What characterizes the fate of a star is its mass if the mass is remarkable that collapses the body will become a star because there is a value called critical mass beyond which the fusion reactions start in the nucleus. If the mass is smaller but the body becomes a planet and here you do not reach those temperatures to initiate fusion reactions.
The sun is a low-mass star that has formed from a collapsing nebula that gave birth to a protostar, and then a star.
Now start the fusion reactions and the energy that is released stops the gravitational collapse starting the stable phase.
The stars are studied based on some parameters such as brightness and surface temperature: these data are placed in a Cartesian reference where the stars will occupy certain regions and not distributed evenly.
The diagonal called main sequence is occupied by the stars who live the life phase stable, ie those in which the gravitational attraction that tends to collapse the star is balanced by the energy produced by fusion causes an internal pressure.
The length of the period of stability depends on the mass: low-mass stars have longer main sequence.
When the star leaves the main sequence begins its final phase: if it is a small star becomes a red giant and then the first white dwarf, while if it is large it becomes a supernova.
The sun is a star of the second generation and is composed of hydrogen, helium, but also heavier elements from supernovae that are synthesized after the explosion undergo conditions of temperature and pressure so high as to form even heavier elements.
Therefore, there are first-generation stars, which should contain only hydrogen and helium, the primitive elements, but in fact have traces of other elements. So you think that there existed very first generation of stars and now are gone.
The sun makes certain movements. During the rotation around its axis the sun takes on two different linear speed of rotation which is greater at the equator to complete the round in 25 days and less at the poles it is complete in about 30 days. This is possible because the sun acts as a fluid and this also affects certain phenomena such as sunspots.
The structure of the sun is organized in concentric layers. The innermost is the core where there is a component of degenerate matter, that is surrounded by a fluid of electrons with protons. Hydrogen atoms are then broken down into their essential components.
The high temperature and pressure allow for the presence of fusion reactions within the nucleus, the atoms in these reactions small get together and give birth to larger atoms. The nuclei repel each other so it is necessary to allow a high kinetic energy collisions between particles. The feedback is a lot of free energy that is transported toward the surface.
The transportation around the nucleus occurs by radiation, because the area is made up of hydrogen and helium at high pressure that does not allow movement of matter.
The photons are then transported in the convection zone where there is movement of matter and energy is transported by convection.
The reactions occur according to the proton-proton chain. The biggest stars is necessary to ensure greater energy and talk of a carbon-nitrogen-oxygen cycle.
The stages of the three proton-proton chain.
The first is that two hydrogen nuclei are based to give an atom of deuterium (hydrogen isotope that has a proton and a neutron). In this reaction you lose a positive charge called the positron and a neutrino.
Neutrinos are tiny particles with no electric charge and that do not interact with matter.
There may be components of the dark mass, ie that part of the Universe can not be detected because it emits electromagnetic radiation, but feel its gravitational effects.
In the second step deuterium fuses with a proton, creating a light isotope of helium and releasing a photon of energy.

In the third step two helium nuclei combine to give a lightweight helium atom releasing two protons.
In essence, four protons are fused to give a helium nucleus. The energy comes from the missing mass that is matter that has been transformed into energy according to the formula E = mc.
Part of the energy used to counteract the action of gravity and some is radiated into space.
The solar surface is called the photosphere, while the solar atmosphere is formed from the chromosphere and the Crown.
The photosphere is located at 6000 K and this determines the color of the sun is a yellow star.
The surface presents some special structures such as granules and sunspots.
The granules are the top part of the convection, because they are brighter and warmer so it seems that the solar surface bubbled continuously.
Sunspots are depressed areas however, are darker because of about 1500 degrees colder than the rest of the surface.
The spots have a darker inner zone of that area outside and a lighter shade called Twilight Zone.
The spots are cyclical and move from a north and south of 40 ° to the equator where they disappear. Reach their maximum of expansion and number next to the north and south of 15 °.
The time period of a cycle is one week.

The spots are due to disturbances of the solar magnetic field. The sun acts as a fluid and rotation disturbs the lines of force in certain areas of the field is intensified by compressing the material and creating depressions.
The chromosphere is observed during the eclipse is made up of hydrogen and the sun glows red.
The surface is frayed and has spicules at the domes of convection.

The crown has an often very powerful, but is rather thin. It 'consists of ionized gas and protons, which have a kinetic energy to escape the gravitational force that rise to the solar wind.

The sun then continually loses material in the form of solar wind affects the whole system.
There are structures related to the sun's ultra-activities:
Prominences jets of hydrogen at high temperature through the chromosphere to fall back on the surface.
Then there are the flares that are flashes of light. The sun also emits stationary radiation in addition to ultra-energy radiation that are much like the cosmic rays.

During periods of solar activity on Earth ultra special phenomena occur due to the interaction of solar particles with the Earth's magnetic field.
For example, the polar auroras occur when the ionized gas of the solar particles interact with the ionosphere. The ionized particles are pushed towards the magnetic poles can come in here and the atmosphere, ionizing gases, which have a particular color and produce the phenomena of light. Another example is the magnetic storms



PLANETS
The planets of the solar system are 9 and are divided into two groups: the terrestrial planets (Mars, Venus, Earth and Mercury), small, made of metal and rock, with a few satellites and very thick atmosphere, and the jovian planets more massive , consisting of gas and ice, but with a metallic core.
The planets describe elliptic orbits coplanar, except Pluto. They all have a rotational motion about its axis in a counterclockwise direction, except for Venus and Neptune, which rotate clockwise.
Jupiter emits more energy than it should and this is perhaps because its mass is close to what determines the difference between star and planet. Perhaps at its core is a reaction of fusion.
Between Mars and Jupiter there is a range of about 1800 asteroids, small bodies of variable shape, running on stable orbits.

There are two hypotheses on the origin of asteroids, some think they are fragments of larger bodies, others are small bodies that have found favorable conditions to join.
In addition to planets and asteroids are other bodies such as meteorites, planets that pass near them attract consumers through the atmosphere. If you arrive on the surface are called meteorites, meteors otherwise.
Some meteorites are composed of rocks, metals, other, other, and both still contain other organic molecules (carbonaceous chondrites).
There are also comets, bodies composed of rock and ice. Some have elliptical orbits and become visible when passing near the sun heat the ice is sublimating.
Others have parabolic orbits, and in and out continuously from the solar system.
Comets formed in the Oort cloud.

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