GEOGRAPHY: Study of earth and related factors is called geography.
Earth: The planet on which we are living that also revolves around the sun.
Sun: A self-luminous body that is a consequence of a nuclear fusion reaction between Hydrogen atoms to form Helium. The sun is a member of a huge group of stars in the galaxy called “Milky Way”.
Origin of Universe
The big bang theory is the most accepted theory regarding the origin of the universe. It was given by the scientist F.F Friedman who discovered that the universe is expanding. To prove his concept he used relative field equations. Later, this concept was supported by Edwin Hubble, an American astrophysicist. He gave the concept of Red Shift which later on came to be known as Hubble’s Law. He gave this theory based on observations he made on “Cepheids” (also known as stars). He said that characteristic colors or spectral lines emitted by stars in galaxies do not have the same wavelength observed in the laboratory. Rather, they are systematically shifted to longer wavelengths i.e. towards the Red end of the spectrum. Such Redshift could occur because the other galaxies are moving away from our galaxy Milky Way. This theory was given in 1929.
In 1965 cosmic “Microwave Background Radiation” was discovered by Penzias and Robert Wilson. Those are high-frequency radio waves that are thought to be leftover radiation of the previous exploitation i.e., the Big Bang.
Galaxy: Galaxies are a huge group of stars. A single galaxy has a billion stars. Galaxies are categorized based on their shape viz:
- Elliptical Galaxy: It has an egg-like shape
- Spiral Galaxy: It is spiral. Our galaxy i.e., Milky way in a spiral in shape.
- Irregular Shape: No irregular Shape
Our galaxy is 10000 million light-years wide and 1,00,000 million light-years long.
Stars: Stars are burning disk of gases, mainly of Hydrogen. Our sun was originated almost 4.5-5 billion years ago and it is supposed to survive for the next 5.5 billion years. The HERTZ-RUSSEL-BERGSCHRUND diagram is used for the classification of stars. It is a graph on which the brightness of the star is plotted. Sun is the type g2 main-sequence star on these criteria. The visible layer of our sun is called Photosphere. The above the photosphere is the layer called Chromosphere and the topmost layer is called Corona which becomes visible only during the eclipse.
The fate of our sun: it will take almost5.5 billion more years to exhaust its entire Hydrogen and it will enter the phase of Red Giant and it will swell up and occupy the orbits of Mercury and Venus coming close to the Earth. After a further period of 1 billion years as a Red Giant, it will turn into White Dwarf. The size of the sun in that stage will be reduced to the size of the earth.
To decide the future of any star, the Chandrashekhar limit is used worldwide. According to this, stars having mass up to 1.4 times that of our sun or less than that forms white dwarf and stars having a move of 3-4 times or greater than the sun forms a black hole.
Black holes: These are interesting spots in the Universe which are known for their intensive gravity which does not allow even light to escape. The center of the blacklight hole is called core which is squeezed to a dot or point of singularity.
The first layer outride the outride they are is called event zone load activity. Light cannot escape from there. Beyond the activity zone, there is an Ergosphere where nothing can stop itself. It has to rotate in the opposite direction with the speed of light to remain stationary.
Artificial Sun- The Thermonuclear Energy program
To overcome the problem of energy security, the international community is running a program that is a scientific research program called ITER- International Thermonuclear Experimental Reactor. This is in a place south of France near the French-Italy border called Cadrich.
This program was started in 2007 and the countries that are contributing are European Union China, Japan, India, U.S, and South Korea & Russia. The largest contributor is the European Union with 46% of total finance.
- The Hydrogen isotope is available on our earth in abundance.
- Deuterium isotope could be extracted from the oceans.
- Tritium shall be taken from the nuclear fusion reactor itself.
- The disposal of nuclear waste of the nuclear fusion reactor is relatively much easier than the nuclear wastes of the conventional nuclear reactors. Nuclear fusion research was started in 2007 and the first plasma is expected to come by the year 2020.