Knowledge About Nature
 
Why is the sky blue? ? ?When the weather was sunny during the day , we will see the blue sky . But in the afternoon , the sky will be reddish yellow . Perhaps many of us who do not know the cause . we only year when the sky is blue , it means that it was already morning and if the sky was reddish yellow sign was late afternoon , z tow ? ? ?Cause of the color of the sky was not separated from the influence of the earth's atmosphere . Gas molecules such as nitrogen , oxygen , argon and water vapor causes the sunlight that consists of length variation wave absorbed . The absorbed light will radiation resulting color spectrum . Although all wavelengths of sunlight is absorbsion , but the blue color that has a low wavelength will terabsorsi more red than blue is the dominant color so visible to the eye . This process is called Rayleigh scattering.Rayleigh explains that light has a smaller wavelength will have a greater intensity perpendaran . Because blue has a small wave long so dominant blue color in the sky. Additionally , perpendaran color is also influenced by the distance to the light source so that the observer at sunset , the distance light source will cause perpendaran further and Rayleigh scattering effect is reduced by the color blue . This process can be seen clearly at sunset , where the red color will be dominant on the horizon line .Planets close to the sunMars is the fourth closest planet from the Sun . After Mercury , Venus and Earth . Named after the ancient Greek god of war . But the planet is also known as the red planet because of the reddish appearance .Mars environment more hostile to life than the state of Planet Venus . However , the situation is not quite ideal for humans . Sufficiently low temperatures and low air pressure , air composition coupled with the majority of carbon dioxide , causing humans to use breathing apparatus if you want to stay there . Missions to the red planet , until the end of the 20th century , yet to find traces of life there , although very simple .This planet has 2 satellites , Phobos and Deimos are . This planet in orbit for 687 days around the sun . This planet also rotates . When the rotation is 24.62 hours .In Greek mythology , Mars is identical with the god of war, namely Aries , the son of Zeus and Hera .On Mars , there is a unique feature in the Cydonia region Mensae . This feature is an hills when viewed from above appears as a human face . Many people who regard it as a proof of the long- extinct civilization on Mars , although at the present time , has proved that the feature is just an ordinary natural appearance .Impact of antiquity Toba eruption destroyed the forest in the Indian subcontinentExperts from the U.S. palaeogeografi study presents the latest findings about the massive eruption of Mount Toba in Sumatra, which presents irrefutable evidence of how the eruption of " mega - colossal " volcano antiquity that occurred 73,000 years ago, causing devastating effects to destroy the existence of exceptional forest areas in the Indian subcontinent which is located 3,000 miles apart from the eruption center who is now a lake Toba .Evidence of research include dust sample were found in the location of mainland India , Indian Ocean , Bay of Bengal , and the South China Sea from the incident eruption expected cast material and volcanic ash up to some 800 km ³ into the Earth's atmosphere and make volcanoes antiquity is gone stay left craters in the earth that is now the lake Toba - with dimensions of length of 100km and a 35km wide volcanic lake greatest evidence of the universal -Described by the eruption of awesomeness is made ​​of dust particles in the layers of the atmosphere blocking sunlight to the earth and reflecting radiant heat back up during the interval of 6 ( six ) years of age to immediately bring up the " Instant Ice Age " in the land - based ice sheets in the research analysis Greenland ice age lasted for 1,800 years -The research was conducted by Prof . Anthropology expert Stanley Ambrose of the University of Illinois - United States , as leader of the main researchers in collaboration with Professor Martin AJ Williams of the University of Adelaide - Australia , published in the scientific journal " Palaeogeography , Palaeoclimatology , Palaeoecology " current issue . Prof . Williams is the first track to prove the presence of dust remains of ancient Toba volcanic eruption in mainland Indian subcontinent in 1982 .In this latest study researchers took samples of marine research is a core layer of boulders from the sea floor depths of the Bay of Bengal and the fossil beds at three (3 ) separate locations on the mainland Indian subcontinent and then perform test analysis of carbon isotopes : carbon isotopes . Carbon isotope analysis results reflect the type of vegetation that existed at a particular place and time period . Heavily wooded area on the left cirian different "fingerprints " of different carbon isotopes from grassland or savanna woodlands .Presents the research findings on the layer 5-7 cm above the dust layer of Toba eruption indicate a change in the presence of fossil vegetation typical plant shrubs and ferns that unlike the case with vegetation sedimentation perennials like trees tropical wilderness areas .Described by Prof . Ambrose that the decline in world temperatures of up to 16 degrees Celsius with the advent of the age " Instant Ice Age " is the case since the state of the earth's temperature will cause a decrease in the impact of decreased rainfall , causing the destruction of wilderness areas . Whereas if judging based on fossil layer thickness such circumstances runs lasted at least until 1,000 years after the eruption .If examined from VEI scale data : Volcanic explosivity Index, which is used USGS - United States Geological Survey - eruption of Mount Toba extraordinary antiquity VEI is classified categories : 8 to so-called " mega - colossal " that among others characterized burst of massive volumes of volcanic material eruption - / + 1,000 km ³ .In comparison eruption g . Tambora ( Th. 1815 ) in the Nusa Tenggara islands included in the VEI scale : 7 , while the terrible events of the eruption g . Krakatau ( th.1883 ) left to live up to the island of Anak Krakatau is now included in the VEI : 6 .At the turn eruptions " mega - colossal " Toba volcano also has implications for the process of human evolution on earth , although it is still a matter of controversy among scientists . Prof . Ambrose himself holding his research study published in the scientific journal " Journal of Human Evolution " in 1998 , including experts who believe that the mega volcano Toba eruption and the Ice Age appearance afterward making the situation was that there was a lack of genetic diversity in modern humans today. Even declared unusual events this almost resulted in people perish .The investigators' hypothesis about the origin of the solar systemMany hypotheses about the origin of the Solar System has been suggested by experts , including :Pierre - Simon Laplace , supporting Hypothesis NebulaGerard Kuiper , supporting Hypothesis CondensationNebula hypothesisNebular hypothesis was first proposed by Emanuel Swedenborg (1688-1772) in 1734 and refined by Immanuel Kant ( 1724-1804 ) in 1775 . A similar hypothesis was developed by Pierre Marquis de Laplace independently in 1796 . This hypothesis , which is better known as Nebula Kant - Laplace hypothesis , states that in the early stages , the solar system is a giant fog . This mist is formed from dust , ice , and gas called a nebula , and that most of the elements of hydrogen gas . Its gravitational force causes it to shrink and rotate the fog with a certain direction , fog temperature heats up , and eventually became a giant star ( the sun ) . The sun continues to shrink and the giant spinning faster and faster , and the gas rings and ice thrown around the sun . Due to gravity , these gases condense along with a decrease in temperature and form planets and outer planets . Laplace argued that the nearly circular orbits of the planets is a consequence of their formation .hypothesis planetesimalsPlanetesimals hypothesis first put forward by Thomas C. Chamberlin and Forest R. Moulton in 1900 . Planetesimals hypothesis says that our solar system formed as a result of another star passing close enough to the sun , in the early days of the formation of the sun . The closeness causes a bulge on the surface of the sun , and the sun with internal processes , interesting material repeatedly from the sun . Gravitational effects lead to the formation of two spiral arms extending from the sun . While most of the material drawn back , some will remain in orbit , it cools and solidifies , and a small -sized objects called planetesimals and they are great as a protoplanet . The objects collide from time to time and form the planets and the moon , while the other remains of material into comets and asteroids .Tidal hypothesis StarsTidal hypothesis first put forward by James Jeans in 1917 . Considered planets are formed due to the approach of another star to the sun . Circumstances which almost collided causing a large amount of material from the attraction of the sun and the other stars by tidal forces with them , which is then condensed into planets . But astronomer Harold Jeffreys in 1929 denied that such a collision is nearly impossible. Similarly astronomer Henry Norris Russell expressed his objection to the hypothesis.Condensation hypothesisCondensation hypothesis originally put forward by the Dutch astronomer named GP Kuiper (1905-1973) in 1950 . Condensation hypothesis explains that the solar system formed from a giant rotating ball fog forming giant discs .Twins star hypothesisBinary star hypothesis was originally proposed by Fred Hoyle (1915-2001) in 1956 . Hypothesis suggests that firstly our Solar System in the form of two stars of similar size and adjacent to one of them burst leaving small pieces . The debris trapped by the gravity of unexploded and start surrounding