Sunday, October 26, 2014

The tiny thing called the sun

       When it was not known that the sun was not the only star in the universe it was regarded as god as the sole sustainer of life on earth. However as astronomy advanced with the development of better telescopes it was discovered that the sun was just another star that is nearest to the earth. There are quadrillions of other stars in the universe many of whom are much larger than our sun

       This stars are basically composed of Hydrogen atoms in plasma state of matter . At the core of the sun  the temperature exceeds 1 million degree centigrade , this temperature is ideal for initiation of a thermonuclear fusion reaction in which two hydrogen nuclei fuse to form a helium nucleus . The mass of this helium nucleus is slightly less than than the combined mass of the two hydrogen nuclei . The disappeared mass is actually converted into energy, the amount of energy is given by the equation (E=mXcXc) . Thus the equation indicates that a massive amount of energy is released this energy is transferred across the solar system in the form of electromagnetic radiation. The same phenomenon goes on in all other stars.

       In terms of volume the sun is more than a million times larger than the earth and in terms of weight the sun is more than 1,00,000 times heavier than the earth. But in the universe there are stars that have a radius that is more than 1500 times that of the sun. Which makes them 3.3 million times larger and more massive than the sun. Every galaxy in the universe has a super massive blackhole at the centre. There are super massive black holes that are 17 billion times more massive than the sun. The stars and other planetary bodies encircle this black hole and revolve around it.

      Just a few days ago NASA shared photograph of a Pulsar that is radiating electromagnetic energy at the rate of 10 million suns a second. While a supernovae which is an exploding star can radiate an amount of energy that is equivalent to what the Sun or any other ordinary star radiates in its entire lifetime before is fades away in a few weeks or few months . 

      So in terms of size and the amount of energy radiated  there are stellar bodies in the universe in front of which our sun appears to be a microsome. 

    

Tuesday, October 21, 2014

Space

"Space the final frontier" the famous beginning line of long running TV soap Star Trek tells us about the ultimate ambition of humankind. Ever since humans existed on the face of earth they wondered what is up there in the sky? What are those twinkling stars ? Why there are some stars that don't twinkle at all? Why does the sun travel across the sky ? and what is there beyond the sky? There were myths and legends in ancient times the sun , moon and stars were called gods in different cultures. Some races called themselves decedents of sun. Some called themselves decedents of moons. Some planet was called the the god of war and another planet was called the goddess of love. The periodic partial and full view of the moon that humans got to see because of the shadow of the earth falling on the moon while the moon was rotating around the earth made some cultures think that the moon was swallowed up by some demon , or some curse from a sage makes it shirk and then regain its shape. Some believed that the position of the stars in the sky determines the future of people .

         This continued for centuries later on ancient astronomers from India, China ,Europe  made different observations of the motions of stars and planets made some calculations about the orbital periods of various planets that can be observed from the naked eye. But the major change came with the invention of telescope by Galileo and the subsequent improvements made in its design, humans started knowing more facts about the universe. They discovered Milky Way as a Galaxy and later on discovered that there are billions of galaxies in the observable universe.

     The General Theory of Relativity helped to explain various phenomenons in the universe that could not be explained by Newtonian theory of Gravity. As humans knew more and more about the universe the desire to visit moon and other planets in solar system grew. Rocket technology has been there since a long time mostly used in war it was also used in World War and there was lot of improvement done in rocket technology between World War 1 and World War 2 , while it was for military purposes then, after the world war the focus began shifting on peaceful uses of rocket technology .The Russians and Americans started working on space technology and developed rockets that were powerful enough the send satellites that would orbit around earth and use it for the purpose of communication. The following years showed rapid development in rocket technology. 

         In the Cold War era there was a race between USA and USSR for space dominance . The USSR became the first nation to launch a satellite and then put a man in space. The following years saw great competition between USA and USSR both countries launched satellites and sent orbiters and probes to different planets including the Moon. The space race ended with the Apollo mission in which man for the first time set his foot on moon. 

    As for India its space journey began with the launch of Aryabhatta the first Indian satellite launched from USSR. So India was actually one of the early entrants into the space age. At that time it was unthinkable for a developing nation to get into space race . Eventually India developed its own satellite launch vehicle the first was SLV that launched Rohini series of satellites with 50% success rate. Followed by ASLV for heavier satellites weighing upto 150 kilos ASLV had a success rate of 25%. Then came PSLV only the first launch was a faliure after that next 26 launches were success however in 1997 the launch was only a partial success since the fourth stage underperformed and the satellite was set to a lower than expected orbit. However the satellites own propulsion was used to get it into the correct orbit. So one can consider that PSLV has a success rate of 96%. 

        The biggest success of PSLV is surely the success in launching Chandrayaan and Mangalyaan .Chandrayaan detected water in form of solid ice present on lunar poles ,  ISRO became only the fourth space agency in the world to successfully launch an orbiter into Mars. India was the first country to have its mars mission as a success. The Mars Orbiter Mission(MOM) cost only $ 74 million a fraction of other Mars missions. 

      Space research is an expensive business with no immediate returns so if other space agencies collaborate with ISRO they will save on costs. They will achieve more for the same amount of money. 

      At the moment only Voyger 1 has gone beyond the solar system. The universe is so vast that the star that is nearest to our solar system is 4.2 light years away. To send space probes to distant stars we would require engines that can travel almost at the speed of light or find some regions in space with wormhole that would help it go directly to a desired location in space.