Hayabusa 2

Hayabusa 2

MINERVA-ll1 of Hayabusa 2 lauched by JAXA have landed on the target surface of Rayugu asteraoid's surface at 3pm in japan time,september 22,2018.

MINERVA-ll1the collective name of RoverA-1,and -2 are in good health,set in motion survey of the surface of asteroid. Where Hayabusa 2 returned to its home position altitude,nearly 20 kilometer from the center of the asteroid and Hayabusa is also in good health.

This image is taken by ONC-T at 64m above the surface of rayugu on 21september at around 13:4JST.

This image os taken by Rover A-1(while moving) on22 september around 11:44JST.In this coloured photo left half is surface of Rayugu and on right half white blur is due to the light of sun.

Sun and stars

Sun and stars

A star is called sun when we partucalarly talk about a solar system. A star  is not just a sphere made up of hot plasm. It is the source of green energy produced by the process of nuclear fusion occuring between hydrogen atom on it. Suns are the centers of there respective solar systems. Its revolving plasma creates a magnetic field and its huge size genrates gravitational field which holds together a solar system. Life time of solar system depends upon its sun's life.

A sun dominates the whole solar system. A solar system starts with the birth of sun in nebula and ends with its death. It holds together matter in solar system. Help planest to have atmosphere. Provides conditions to grow life on planets. Nothing more is important then a sun in a solar system. There are billions and billions of stars in universe from which there are mainly four types of star F(blue to white),G(white to yellow),K(orange to red) and M(red) having approximate surface temperature of 6000-7500K,6000-5000K,5000-3500K and 3500K respectively. where F type have least life time where M type have maximum life time.They are like cells of a body(glaxy).

Nuclear Fusion

Nuclear fusion is the phenomenon of combining or fusing two or more lighter nuclei to form a more stable heavy nucleus with the liberation of vast amounts of energy.
                   
                                A huge amount of energy is required for the fusion of nuclei.High temperature(millions of degrees)and high pressure(millions of pascals)are needed to bring about fusion.

   Examples

(1)Two deuterons can join together to form a Helium-3 nucleus and a neutron.the nuclear reaction can be represented as

Such nuclear reactions are the source of energy in the sum other stars.

The source of energy in both nuclear fusion and nuclear fission is the same,i.e,disappearance of a certain mass in the process which appears in the form of energy. the sum of masses of the products is somewhat less than the sum of the masses of the reactants.This difference in masses before and after the nuclear reaction is called the mass defect(,m).It is this mass defect which appears in the form of nuclear energy according to Einstein's mass-energy relation: 

                                                                                           E= mc²
Where C is velocity of light in vacuum.
This famous equation was derived by Albert Einstein in 1905.

Nuclear fission

Nuclear fission is the phenomenon of splitting of an unstable nucleus of a heavy atom(e.g.-uranium,plutonium or thorium,U-235)into two medium weight nuclei with liberation of an enormous amount of energy.The fission is carried out by bombarding the heavy nuclei with suitable projectiles,usually slow neutrons.
                                                       
                                                   The phenomenon was discovered in the year 1939 by two German scientists Otto Hahn and Fritz Strassman. The bombarded U-235 with low energy neutrons, called thermal neutrons.Just as a glass ball when hit with a hammer may shatter in different sizes,U-235 nucleus splits up broadly into two groups of nuclei:
  (1) a heavy group of nuclei,with mass number in the range A=130 to A=149.
  (2) a light group of nuclei,with mass number in the range A=85 to A=104.
     
           out of these, the most prominent products and Barium with mass number 139 and Krypton with mass number 94.three neutrons(or in some cases two neutrons)are produced along with enormous amounts of energy in the form of gamma rays ; heat energy and light energy.Fig. 1 represents line diagram of the fission of U-235.As the fission produces two neutrons or three neurons,the third neutron is shown with a light shade.

Figure. 1

             
                           In the form of a nuclear reaction,we represent nuclear fission of U-235 as follows :

The materials which can be fissioned even with low energy neutrons are called fissile materials.

These materials are used as fuels for nuclear power plants and also for production of atom bombs.

  The amount of energy produced in nuclear fission is enormous.One kilogram of U-235,on fission,produces as much energy as 2500 tons of coal produces on burning.

black holes

science -i love science.science is divided into three parts.physics,chemistry and biology.i know mostly about physics.

Most mysteryst  thing for physicists is black hole. some people think that a black hole is a way to go to another parllal univers and some think that it is a time portal.black hole is very dangers for us now because it has a very dangers and power full gravitational field with which it can engulf many planets and it also attract and engulf light coming from suns.
scientists think that the black hole were very rare before nine tenth century but after the discovery of  a black hole at the center of our galaxy.this mith is broken.now they know that every galaxy has a black hole at its center and they are as many as the galaxys where in the universe.

Very less people know that our sun is rotate around a super massive black hole. which is made up after combining small black holes.this black hole is known as Sagittarius A*.Sagittarius A* was discovered on February 13 and 15,1974,by astronomers Bruce Balick and Robert Brown using the baseli interferometer of the National Radio Astronomy Observatory.Sagittarius A* is 25000 to 28000 light years away from us.
when a sun die it blasts and from its waste new sun and planet born and also a black hole born.many scientists give there views about black hole but only some views are proved.black holes are mysterywhich is not solved than.there are many things in space which is unfounded than or a mystery and black hole is one of them.