THE SOLAR SYSTEM -BASIC

There are many stars in the universe that host planets; those are also solar systems like the one in which we dwell, some with more, and some with less planets revolving around the star. That does not mean that we have found life in those planets found around other stars, because they might not be suitable for developing life. Water is the major compound that we are looking for among other elements. Our star is the Sun. In this 7 min video, you can find more about the Solar System.

http://www.showme.com/sh?h=aCzZ17I

As we commonly know, rocks are classified as igneous rocks, metamorphic rocks, and sedimentary rocks. Igneous rocks are rocks that have been melted, and are formed when a hot molten rock cools, from magma. These rocks melt in the upper mantle of the Earth and below the crust. The igneous rocks are rich in minerals mainly silicates, like feldspars, that are silicates of aluminum, or potassium (alkaline feldspars) or rich in sodium and calcium like in the plagioclase feldspars. This magma that moves upwards towards the surface of the Earth in the mantle could cool underground, forming intrusive rocks, and when magna, like after expelled by a volcano, is lava that will form extrusive rocks. The molten rock will solidify in different ways, depending on the rate of loss of heat. The magma in the mantle and deep in the crust, will cool down much slower that the lava that comes out from a volcano; this rate of cooling will give rocks different forms and structure. If the cooling is very fast, it can produce rocks that look like glass with no crystal forms, like obsidian.

Metamorphic rocks are modified by high temperature and pressure do to the forces acting on the crust, and the interior of the Earth. These rocks are chemically combined with many ingredients that are then given the names to these rocks accordingly, like marble, gneiss and slate, for some examples.

Sedimentary rocks are the result of the erosion by water (rain, ice) and air (winds). These can only happen in planets that have an atmosphere were winds can form, and flowing water that can transport the rocks over the surface. Shale and sandstone are the most abundant sedimentary rocks on the surface of the Earth, in a proportion of 70% shale and 20% sandstone.

But what about primitive rocks? These rocks were not transformed inside planets by pressure and temperature changes as we just read for the igneous and metamorphic rocks. There primitive or original rocks are common in asteroids and what we can see in the meteorites.

Geologists also teach us about breccias, rocks that are broken that show sharp edges glued together by high temperature and pressure, but not from the interior of the Earth, but from impacts that can be discover in the interior of craters.

Have you ever thought about the reason why, when we have in the northern countries, like in the USA and Canada, and the countries in Europe, cold winter season, and in South America, like in Argentina and Chile during the same time a warm summer? First, we need to remove the idea that it is because of the distance to the sun. Actually, yes, during the summer in the northern hemisphere we are closer to the sun, but it is not only the northern hemisphere that is closer to the sun, it is the whole Earth that is closer to the sun, during the summer in the north. But why is it summer in Argentina or in Australia, and in the Northern Hemisphere cold winter? It has to do with the inclination of the Earth axis of rotation. The axis of rotation will always point toward the northern star, Polaris. The Earth will not point to another star while revolving around the Sun. Because of that, the Sun will have an apparent motion between the southern hemisphere to the northern hemisphere passing the Equatorial line. The Sun describes a curve in the sky that is called the ecliptic, and when the ecliptic cuts the Equator on March 21, we call this point the Venal Equinox. This is the point when the day and the night have equal lengths. In the picture you can see how the sun is sending more warm rays to the north in June, and less to the south, and in December is the opposite. Just the axis of inclination!

The states of matter depend on how the average distance between their molecules is compared with the size of the molecules themselves. In a gas, the molecules are separated in average by distances much larger than the molecules sizes. There are, as we know, substances in solid state at normal temperature and pressure. Their molecules are not individual isolated units like in the gaseous state. The separation of the molecules in a solid state can be considered in the order of the size of the molecule itself, and the force that keep the molecules together are of the same magnitude as the strength of the forces that keep the atom in the molecule together. This is typical os solids that present a crystal lattice formation.