Mighty Sun

SUN:Unlimited Source of Energy 

           

 

           Sun,star around which Earth and the other components of the solar                        system revolve. It is the dominant body of the system, constituting more than 99 percent         of its entire mass. The Sun is the source of an enormous amount of energy and the                basis of all power , a portion of which provides Earth with the light and heat necessary            to support life. The Sun is personified in many mythologies: the Greeks called                         it Helios and the Romans called it Sol.

 

        The Sun is classified as a G2 V star, with G2 standing for the second hottest stars of the         yellow G class—of surface temperature about 5,800 kelvins (K)—and the V representing         a main sequence, or dwarf, star, the typical star for this temperature class. The Sun                exists in the outer part of the  Milky Way Galaxy and was formed from material that had            been processed inside a Supernova.

 

         Index:

•           Our Sun
•           Profile
•       Sun as a star

•       Atmosphere

•  Photo sphere
•  Chromo sphere
•  Corona

 

• Internal Structure
• Core
• Radioactive Zone
•  Convective Zone

•  Magnetic activities
• Sun: Nuclear Powerhouse

 

 

           Physical Characteristics:

     

                   

            

                    

                    

                            

Parameter	Value
Mean Diameter	1.392 x 106     km
Equatorial Radius	6.955 x 105   km
Mass	1.989 x 1030 kg
Average Density	1.408 x 103 kg/m3
Equatorial Surface Gravity	274 m/s2
Temperature	5778 K
Luminosity	3.846 x 1026 w/m2
Escape Velocity	617.7 m/s2

1. Sun is 13,00,000 times larger than Earth. 109 Earth requires to cover Sun.
2.  Light takes 8.24 min. to reach Earth.
3.   It emits EM.

Rotation:

 

At equator: 25.05 day

At pole: 34.3 day

Rotation velocity: 7.189x10³ km/h

 

Rotation of sun in its different part varies. It is not similar to Earth.

 

        Atmospheric Layer:

                Sun has also an atmosphere with different layer like Earth.

 

                #Sun has 3 layers:

·                                 Photosphere

·                                 Chromosphere

·                                 Corona

 

          Photosphere:

        

    The photosphere is the deepest layer of the Sun that we can observe directly. It reaches from the         surface visible at the centre of the solar disk to about 250 miles (400 km) above that. The temperature         in the photosphere varies between about 6500 K and 4000 K. Most of the photosphere is covered by            granulation.

 

      Granulation: the rice-grain-like structure of the solar photosphere; granulation is                      produced by upwelling currents of gas that are slightly hotter, and therefore brighter, than         the surrounding regions, which are flowing downward into the Sun.

 

 

      Sun’s outer atmosphere is transparent, allowing us to look a short distance through it. But       when we try to look through the atmosphere deeper into the Sun, our view is                          blocked.The photosphere is the layer where the Sun becomes opaque and marks the              boundary past which we cannot see. The energy that emerges from the                                   photosphere was originally generated deep inside the Sun. This energy is in the form of           photons, which make their way slowly toward the solar surface.Outside the Sun, we can          observe only those photons that are emitted into the solar photosphere, where the density       of atoms is sufficiently low and the photons can finally escape from the Sun without                  colliding with another atom or ion.

      So, photons making their way through the Sun are constantly bumping into atoms,                  changing direction, working their way slowly outward, and becoming visible only when              they reach the atmosphere of the Sun where the density of atoms is too low to block their       outward progress.

     Astronomers have found that the solar atmosphere changes from almost perfectly                    transparent to almost completely opaque in a distance of just over 400 km; it is this thin          region that we call the photosphere, a word that comes from the Greek for “light sphere”.

     Observations with telescopes show that the photosphere has a mottled appearance,              resembling grains of rice spilled on a dark tablecloth or a pot of boiling oatmeal. This              structure of the photosphere is called granulation. Granules, which are typically 700 to         1000 km in diameter, appear as bright areas surrounded by narrow, darker (cooler)                 regions.The lifetime of an individual granule is only 5 to 10 minutes. Even larger are super      granules,which are about 35,000 km across (about the size of two Earths) and last about         24 hours.

     Chromosphere:

              The chromosphere is a layer in the Sun between about 250 miles (400 km) and 1300 miles (2100     km) above the solar surface i.e. photosphere. The temperature in the chromosphere varies between            about 4000 K and 8000 K, so in this layer (and higher layers) it actually gets hotter if you go further away     from the Sun, unlike in The lower layers, where it gets hotter if you go closer to the centre of the Sun.            Really properties of sun is unique and  interesting.

     Until this century, the chromosphere was visible only when the photosphere was                    concealed by the Moon during a total solar eclipse. In the seventeenth century, several         observers described what appeared to them as a narrow red “streak” or “fringe” around the      edge of the Moon during a brief instant after the Sun’s photosphere had been covered.            The name chromosphere, from the Greek for “colored sphere,” was given to this red           streak.

    Observations made during eclipses show that the chromosphere is about 2000 to 3000 km     thick, and its spectrum consists of bright emission lines, indicating that this layer is                 composed of hot gases emitting light at discrete wavelengths. The reddish colour of the         chromosphere arises from one of the strongest emission lines in the visible part of its             spectrum—the bright red line caused by hydrogen, the element that, as we have already        seen, dominates the composition of the Sun.

    #There is another region called Transition Region is found, where temperature of sun  increases                 rapidly.

    Corona:

 

The corona is the outermost layer of the Sun, starting at about 1300 miles (2100 km) above the             solar surface (the photosphere). The temperature in the corona is 500,000 K up to a few million K. The         corona cannot be seen with the naked eye except during a total solar eclipse, or with the use of a                 coronagraph. The corona does not have an upper limit.

    The corona extends millions of km above the photosphere and emits about half as                     much light as the full moon. The reason we don’t see this light until an eclipse occurs is the      overpowering brilliance of the photosphere. Just as bright city lights make it difficult to see      faint starlight, so too does the intense light from the photosphere hide the faint light from         the corona. While the best time to see the corona from Earth is during a total solar                 eclipse.

    Studies of its spectrum show the corona to be very low in density. At the bottom of the             corona, there are only about 10⁹ atoms/cm³, compared with about 10¹⁶ atoms/cm³ in the        upper photosphere. The corona thins out very rapidly at greater heights, where it                     corresponds to a high vacuum by Earth laboratory standards. The corona extends so far         into space—far past Earth—that here on our planet, we are technically living in the Sun’s         atmosphere.

    #Fact: Surprisingly the name of the virus which locked down the whole world this year is                     similar to name of the outermost layer of sun’s atmosphere.

    Internal Structure:

    Core:

          The core of the Sun is considered to extend from the centre to about 0.2 to 0.25 of solar radius.It is          the hottest part of the Sun and of the Solar System. It has a density of 150 g/cm³ at the centre, and a          temperature of 15 million kelvins. The core inside 0.20 of the solar radii contains 34% of the Sun's               mass,but only 0.8% of the Sun's volume. Inside the 0.24 solar radius is the core which generates 99%          of the fusion power of the Sun.

 

    Radioactive Zone:

            The Sun's radiative zone is the section of the solar interior between the innermost core and the            outer convective zone. In the radiative zone, energy generated by nuclear fusion in the core moves            outward as electromagnetic radiation. In other words, the energy is conveyed by photons. When the            energy reaches the top of the radiative zone, it begins to move in a different fashion in the convective        zone. In the convective zone, heat and energy are carried outward along with matter in swirling flows        called convection cells.

    The inner parts of the Sun (core and radiative zone) spin differently than the outer layers (convective             zone). The boundary between these two types of rotation, which lies between the radiative and                    convective zones, is called the tachocline.

 

    Convective Zone:

          It is made out of plasma. The convective zone, like the rest of the Sun, is made up            entirely of plasma. A plasma is a 'gas' that conducts electrical currents, just like a wire            does. The 'gas' contained in neon light bulbs is a plasma for example. The plasma in the         convective zone is mainly made up of hydrogen (70% by mass), helium (27.7% by mass)        plus small quantities of carbon, nitrogen and oxygen.

    It is convecting (boiling). As we have seen above, the bottom of the convection zone is            heated by the radiations coming out of the radiative zone, a bit like a room is heated by a        radiator. The temperature at the bottom of the convection zone is 200,000° C. At the                same time the top of the convection zone is being cooled by the creation of light. The                temperature at the surface is only about 5700° C. Thus, there exist a large temperature            difference between the base and the surface of the convection zone.

 

 

 

    SUN: Nuclear Powerhouse:

 

     The Sun puts out an incomprehensible amount of energy—so much that its ultraviolet             radiation can cause sunburns from 93 million miles away. Evidence shows that the Sun         formed about 4.5 billion years ago and has been shining ever since. How can the Sun                   produce so much energy for so long?

    The Sun’s energy output is about 4 × 10²⁶ watts. This is unimaginably bright: brighter than     a trillion cities together each with a trillion 100-watt light bulbs. The total amount of energy         produced over the entire life of the Sun is staggering, since the Sun has been shining for         billions of years. Scientists were unable to explain the seemingly unlimited energy of stars        like the Sun prior to the twentieth century.

    When striving to understand how the Sun can put out so much energy for so long,                    scientists considered many different types of energy. Nineteenth-century scientists knew of     two possible sources for the Sun’s energy: chemical and gravitational energy. The source of     chemical energy most familiar to them was the burning (oxidation) of wood, coal, gasoline,     or other fuel. We know exactly how much energy the burning of these materials can                 produce. However, we know from geologic evidence that water was present on Earth’s            surface nearly 4 billion years ago, so the Sun must have been shining brightly (and making     Earth warm) at least as long as that.

    Conservation of Energy:

    Other nineteenth-century attempts to determine what makes the Sun shine used the law of     conservation of energy. Simply stated, this law says that “Energy cannot be created or         destroyed, but can be transformed from one type to another, such as from heat to                    mechanical energy”. The steam engine, which was key to the Industrial Revolution,                 provides a good example. In this type of engine, the hot steam from a boiler drives the             movement of a piston, converting heat energy into motion energy.

 

    Gravitational Contraction as a Source of Energy

    If we assume that the Sun began its life as a large, diffuse cloud of gas, then we can                calculate how much energy has been radiated by the Sun during its entire lifetime as it has     contracted from a very large diameter to its present size. The amount of energy is on the         order of 10⁴² joules. Since the solar luminosity is 4 × 10²⁶ watts (joules/second) or about        10³⁴ joules per year, contraction could keep the Sun shining at its present rate for roughly       100 million years.

    It was only in the twentieth century that the true source of the Sun’s energy was identified.        The two key pieces of information required to solve the puzzle were the structure of the            nucleus of the atom and the fact that mass can be converted into energy.

    To imagine what would happen if this hypothesis were true, picture the outer layer of the         Sun starting to fall inward. This outer layer is a gas made up of individual atoms, all                moving about in random directions. If a layer falls inward, the atoms acquire an  additional     speed because of falling motion. As the outer layer falls inward, it also  contracts, moving        the atoms closer together. The temperature of a gas is a measure of the kinetic                        energy (motion) of the atoms within it; hence, the temperature of this layer of the Sun             increases. Collisions also excite electrons within the atoms to higher-energy orbits. When        these electrons return to their normal orbits, they emit photons, which can then escape             from the Sun Kelvin and Helmholtz calculated that a contraction of the Sun at a rate of only     about 40 meters per year would be enough to produce the amount of energy that it is now     radiating. Over the span of human history,the decrease in the Sun’s size from such a                slow  contraction would be undetectable.

 

        # Thanks, see you soon. 🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞🌞