Possibility Of Life In Solar System

                         Formation Of Sun 

   

 Massive Concentration of interstellar gas and dust created a molecular cloud resulting in the formation of Sun's birthplace . Cold temperature caused the gas to clump together , growing steadily denser . The densest  part of the clouds collapsed under its own gravity , resulting  in the formation of the wealth of the young stellar objects known as protostars .Gravity continued to collapse the material onto the infant object, creating a star and disk of material from which the planets would form. When fusion kicked in , the star began to blast the stellar wind which helped to clear out the debris and stopped it from falling inwards.  

 The young protostar  was a  ball of hydrogen and helium not yet powered by fusion. Over tens of millions of years  the temperature and pressure of material inside increased , jumpstarting the fusion of hydrogen that drives the sun today .

   Existence ,Evolution, Possibilities Of Life In Our Solar System 

                                

                                Origin Of Earth

  

Formation of Earth took place when gravity pulled swirling gas and dust thus leading to the formation of a third planet in our solar system from Sun . Earth consist of the central core , rocky mantle and solid crust .

At the early stage the Earth's surface was under continuous bombardment by meteorites and intense volcanism , that is believed to be severe due to large heat flow and geothermal gradient of that era. This first era is also known as Hadean Eon.  Outgassing and volcanic activity produced the primordial atmosphere , and evidence states that liquid water existed at this time, despite the conditions on the surface. Condensing  water vapor ,  augmented by ice delivered by comets , accumulated in the atmosphere and cooled the molten exterior of the planet to  form a solid crust and produced the oceans .

                                 Evolution Of Earth 

Evolution of the planet earth and origin of life is reviewed under structural functional , biochemical , chemical and physical aspects . The biosphere is organized as self regulating, thermodynamically open system , which however consist of individual organisms .They are operating as biochemical closed structures , which have the ability to transport energy and matter actively from there surrounding environment to their interior .

     Theories regarding past existence of life in Mars and Venus 

              Mars

Four billion years ago , the Martian surface was quite habitable , featuring rivers , lakes and even a deep ocean , some astrobiologists  view ancient mars as even better cradle for life than Earth . More than 90% of Earth's methane is produced by microbes and other organisms , so its possible the gas is a signature of modern Martian Life . Mars early atmosphere was rich enough in heat trapping carbon dioxide to create a greenhouse effect , warming the surface . An oxidized form of element molybdenum , which may have been crucial to origin of life was likely available on the Red Planet Surface long ago unavailable on Earth, said Benner , who presented his findings recently at the annual Goldschmidt Geochemistry conference in Florence , Italy.  Earth was completely covered with water while ancient Red planet had substantial dry areas . All of this liquid would had made it difficult for Boron , which currently found only in extremely dry places , to form in high enough concentration on Earth when life was first evolving .

           Venus

The surprise discovery of gas that could be a sign of life on Venus has reignited scientific interest in Earth's closest neighbor . Researchers and Space agencies are racing towards the planet to confirm the presence of  the  gas , called phosphine and to investigate whether  it could really be coming from a biological source . Recently scientist have revealed that they had found phosphine in Venus's atmosphere around 55 kilometer above the surface. Astrobiologists  have flagged phosphine a toxic compound of hydrogen and phosphorous as a possible signature for life on other planets and it is made by some organisms on Earth .

    

                                     Gas giants in our Solar System

         Jupiter 

        Jupiter's atmosphere resembles that of the sun , made up mostly of hydrogen and helium . Dark bands and colorful lights that surround Jupiter are created by strong east west winds in the planets upper atmosphere traveling more than 355 mph (593 km/hr) . White clouds in the light zone are made of crystals of frozen ammonia , while darker clouds made up of other chemicals are found in Dark belts . The most extra ordinary feature in Jupiter is the great Red spot , a giant hurricane like storm that's lasted more than 300 years . At its widest the great Red spot is twice the size of earth . At the deepest visible levels are the blue clouds . Inside the atmosphere, diamond rain may fill skies. 

      

                             Saturn

       

      Adorned with thousands of beautiful ringlets , Saturn is unique among the planets . It is not the only planet to have rings made of chunks of ice and rock but none are as spectacular or as complicated as Saturn's.  Twice every 29 and a half years the great planet Saturn appears ring less . Saturn doesn't have a true surface . The planet is mostly swirling gases and liquids deeper down. Saturn is blanketed with clouds that appear as faint stripes , jet streams and storms . Saturn rings are thought to be pieces of comets , asteroids or shattered moons that broke up before they reach planet, torn apart by Saturn's powerful gravity . They are made of billions of small chunks of ice and rock coated with another material such as dust . The rings would mostly look white if you look at them from the cloud top of Saturn , and interestingly each rings orbit at different speed around the planet . 

  

          Uranus  

    

   It is very cold and windy . The ice giant is surrounded by 13 faint rings and 27 small moons as it rotates 90 degree angle from the plane of its orbit. The unique tilt makes Uranus appear to spin on its side , orbiting the Sun like a rolling ball . The 80 percent or more mass of the planet is made up of a hot dense fluid of icy materials  (water , methane  and ammonia) above a small rocky core .Uranus is slightly larger in diameter than the Neptune , yet smaller in mass, its the second least densest planet. Saturn is the least dense of all. The blue green color of the Uranus is from the methane gas in its atmosphere. 

               Neptune 

Neptune's cloud cover has an especially blue tint that is partially due to an unidentified compound and the result of the absorption of red light by methane in the planets mostly hydrogen-helium atmosphere . Neptune reveals a Blue planet since its an ice giant , it posses a thick slushy fluid mix of water , ammonia and methane ices under its atmosphere and is roughly 17 times Earth's mass and 58 times its volume. Neptune's magnetic poles are tipped over by roughly 47 degrees compared with poles along which it spins .Neptune unusual rings are not uniform , but posses bright thick clump of dust called arcs.