The Universe was created from a Big Bang that occurred in a space of the size of a hair and in approximately one billionth
of a second. There are millions of Milky Ways in this Universe and our Milky Way is one of them. Milky way is a huge cluster
of stars and contains approximately 400 million stars. It takes 1,00,000 (1 lakh) light years for light to reach from one
end of the Milky Way to the other. The milky way can be divided into 3 major parts i.e. 1) the auora 2) the middle part which
is in the form of a ballooned plate and 3) the carona. Our sun is a medium sized star situated at the central hard of the
ballonedballooned plate. It is situated approximately at a distance of 30 to 35 thousand light years from the center of the
Milky Way. The breadth of the space of Milky Way where our sun is situated is approximately 2500 to 3000 light years. The
diameter of the ballooned area is approximately 15,000 to 20,000 light years. This part is heavily populated with stars.
There is a black hole at the center of the Milky Way. The diameter of the aura surrounding the Milky Way is 65,000 light
years. On the exterior of the aura is carona whose diameter are approximately 2,00,000 to 3,00,000 (two lakhs to 3 lakhs)
light years from the centre. The Milky Way is spirally shaped; i.e. spiral arms originate from its centre. Normally stars
are seen in these arms. The interior of the spiral arm contains stars, gaseous clouds and dust particles. Sagittarius,
Orion and arms have been located till date. Our sun is situated in the in the Orion arm. It takes 225 million years for
our sun to complete one orbit around the Milky Way and the sun has completed 20 orbits ever since its birth. The Milky Way
is densely populated with Nebulas, Stars, and Gases and dust particles. Gases and dust particles work on the principle of
Hydro Dynamics, while starts make movement according to Kaplers principle. That is the reason the density of gases and dust
particles does not remain the same in the Milky Way. The particles specially get drawn towards the spiral arm. This attraction
induces acceleration in them and due to density of the Milky Way Density Waves are created. These waves create insurmountable
pressure on the neighbouring gaseous clouds and Shock Waves are created. These shock waves create stars in the Milky Way.
According to laws of hydrodynamics gases and dust particles remain together in the spiral arm and keep orbiting the centre
of the milky way, due to this the sun also has to orbit alongwith them. The further a sun is from the centre of the milkyway,
the time taken for orbiting the centre is also more. Though our sun is approximately 30,000 light years away from the centre
the time taken by it to orbit around the Milky Way is the same as the time taken by gases and dust particles in the spiral
arm.
The spiral arm in which our sun is situated is the Orion arm, on its inner side is the Sagittarius arm and on the outer
side is arm. While we are looking at the Sagittarius arm our sight is towards the centre of the Milky Way. The Sagittarius
arm is also densely populated with stars. Our sun was actually born in the Sagittarius arm.
Approximately 4 5 million years ago it left the Sagittarius arm and today it is situated in the Orion arm and in approximately
3 5 million years it will enter the arm. If at that time our solar system passes closer to a new born star that is approximately
30,000 light years away, it will kill all life on earth, because a new born star activates high speed particles to 30,000
light years. If these particles come in contact with the solar system will definitely destroy the earth. Apart from this
in another 1.5 million years, sun must have lived its life and due to that earth will also meet its end.
According to calculations of scientists, those starts that are situated in the border section of the Milky Way i.e. approximately
1,500 light years broad and is 30,000 light years away from the centre, can only save themselves for a longer period from
the new born starts. This part of the Milky Way can contain planets that can be conducive for sustaining life. This part
may contain approximately 1 million starts which may in turn contain 1 crore planets. The search for life sustaining planets
in our milky way can be conducted in this part. The upper and lower portion of the Milky Way contains groups of stars known
as Globular Clusters. These clusters may contain starts numbering from 100 to thousands. Their level of orbit is different
from one another. Due to this the average distance among the stars will be less, their planets will remain very hot and hence
life cannot exist on such planets.
Even though there are 400 million stars in our milky way, but when observing from evolution of life point of view due
to some reason or the other stars becomes unsuitable. This shows how rare life creation is.
The above mentioned information so far has been about our Milky Way. Now let us get some information about the Universe.
Alike our milky way the Universe contains 100 billion milky ways. Approximately 15 billion years ago in a space of the size
of a hair and in one billionth of a second Big Bang occurred and the Universe was created. At that time all things, matter,
liquid, gases, energy, so much so that directions and time also did not exist. As the Universe began to expand and cool down
all these things started coming into existence.
At the time of Big Bang the Universe was situated in a very infinite small space and was so hot as if millions of suns
were burning together. As the Universe was one thousandth of a second old, its temperature had fallen 10 billion degrees.
Initially Quark was created, it is known as the creator of todays protons and neutrons. By the time the Universe had reached
the age of one hundredth of a second it was failed up with protons, electrons, positrons and neutrinos. These three quarks
combined together to form neutrons and protons, but these particles are found in very less quantity. By the time the Universe
was a second old, the temperature had further fallen by 10 million degrees and protons did not have so much energy left with
them that they could collect their own particles.
The most historic event took place after the Universe was 100 seconds old. Its temperature had further fallen by some
lakh degrees. The protons and neutrons were moving very slowly, at that time the force was created that is responsible for
holding the protons and neutrons to the nucleus. From here on the era of Nuclear Synthesis started when light Nuclear
were created, they contained Helium and Lithium gases, but for creation of heavy elements like oxygen higher temperature was
required. But as the Universe was expanding at the same rate it was cooling down. The heavy basic elements later were to
become atomic furnaces in the stars.
After nearly 3,00,000 (3 lakhs) years when the temperature of the Universe was nearly 3,000 degrees, Atoms began to form
and adopted various routes. Gravity brought liquids closer and formation of Milky Way began.
There are 4 major forces in the universe :
1) Gravity It is responsible for weight of liquids and speed of stars and planets.
2) Electro Magnetic Force It creates forces like magnetism, electric light and many other things.
3) Strong Nuclear Force - It binds the protons and neutrons to the nucleus.
4) Weak Nuclear Force It manages the creation and destruction of nuclear particles.
All the known forces in the nature except Gravity are co-ordinated by a particle named Boson which is between quark and
Laptono.
The universe has been expanding at a speed of 1,60,000 miles per hour and is simultaneously cooling down. If it continues
to expand at this rate, then it can end up by getting too cold or if it starts contracting after a particular point, then
it would end up due to immense heating.
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