THE GREAT UNIVERSE

 

 1 .CREATION OF THE UNIVERSE 

What existed before the universe? How and when was it created? Nobody can really be certain of these answers, but the Big Bang model is considered to be responsible for this miraculous creation!

·     WHAT IS THE BIG BANG MODEL? 

The big bang model is a theory about how the universe was formed and how it evolved. In fact, among the many theories on this subject, the Big Bang is the most popular. The essence of this theory is that the universe emerged from a state of very high temperature and density. This caused a violent collision on an extremely large scale, which is why the model is called the Big Bang. The theory was based on the observation that several other galaxies were moving away from the Milky Way galaxy in different directions and there seemed to be an ancient force responsible for this. Scientists estimate that the Big Bang happened nearly 13.8 billion years ago when the universe came into being. 

·     WHO THOUGHT OF THE BIG BANG MODEL?

In 1927 a Belgium priest and astronomer, Georges Lemaitre made a very important discovery – he independently proposed that the universe is expanding. In 1922 a Russian mathematician Aleksandr Friedmann had also arrived at this conclusion. Lemaitre claimed that the universe began as a single point, that is, it had a finite beginning. It later expanded into its current vastness. He also said that it could keep growing. His formulation of the modern Big Bang theory was based on the work of Albert Einstein. Two years later, American astronomer Edwin Hubble conformed Lemaitre’s theory that the universe was, in fact, expanding. He observed that galaxies were moving away from earth and that the galaxies that were farther away were moving at a faster rate than those nearby. This meant that if things were moving away from each other, then perhaps a long time ago they existed close to each other

While Dutch astronomer William De Sitter had also earlier considered an expanding model of the universe, Lemaitre’s theory, which was revised by George Gamow  and others in the 1940s, remains the principal model of the universe .

 

                                                                        

 

 

·        THE THEORY

 According to the Big bang theory, the universe starter off as a hot and extremely dense point, about a few millimeters wide. approximately 13.8 billion years ago , this tiny point (or Singularity) exploded in a violent bang from which all of matter, energy, space and time were created.

 Different theories state that immediately after Big Bang , there probably was a colossal sea of protons, electrons, neutrons and other particles . with time , the universe continued to cool , resulting in the decay and recombination various particles . protons and electrons may have to form neutral hydrogen . the universe may have been opaque before the recombination , due to the scattering of light by the free electrons . once neutral atoms were formed , it became transparent . the atoms joined together and after a very long time formed stars and galaxies . The initial few stars were responsible for creating bigger atoms and also for groups of atoms known as molecules . this led to the birth of several more stars . Simultaneosly , galaxies were banging against each other and coming together . during this process of formation and dying of stars , things like asteroids , comets , planets and black holes were created .

 Since the theory predicted that the early cosmos was in a very hot state and that the gases cooled with expansion , it would most probably also be filled with radiation or remains of heat from the violent explosion . the remains of this hot dense matter are called cosmic microwave background ( CMB ) radiation CMB radiation today is very cold and is similar to what is used to emit tv signals through antenna . a lot of information about the early universe can be gathered from CMB , the earliest known form of the radiation . CMB was first predicted by Ralph Asher Alpher in 1948 , when he was doing research about the Big Bang model along with Robert Herman and George Gamow .

 

           

 

 

2. MATTER & ANTIMATTER 

In our universe , anything that has mass , takes up space and has volume is called matter .

This means that ordinary or regular matter is something we can feel , touch and even taste . Antimatter is the opposite . It is matter made up of antiparticles that have properties opposite those of normal matter . antiparticles are subatomic particles having the same mass as a given particle , but with an opposite electric charge . to understand antimatter , let us first take another look at what matter is .

 

·     WHAT IS MATTER ?

Everything around us – all solids , liquids and gasses comprise atoms which are the main ingredients of  all matter . at the center of each atom is a nucleus which comprises two different particles – protons and neutrons . the nucleus is surrounded by smaller particles called electrons . both protons and neutrons have an electric charge . protons are positively charged and electrons are negatively charged .

When there are two opposite charges – negative and positive – they attract each other , but when the charge is the same , they repel each other , for instance , when you rub a plastic ball against your hair , you see your hair rising up . due to the charge created because of friction . when you rub them against each other , the protons and electrons get unevenly distributed over the ball and your hair . this results in the ball getting either positively or negatively charged and it stiks to anything which has an opposite charge .

·     WHAT IS ANTIMATTER ?

Antimatter Is almost the same as regular matter , but it comprises of antiprotons , antineutrons and antielectrons or positrons . the main difference between the particles of matter versus antimatter is that , they have the reverse charge . antiprotons therefore are negatively charged and antielectrons are positively charged .

3. IT’S A DARK, DARK UNIVERSE. 

human beings have made great scientific progress in all fields including the exploration of space and understanding the universe . yet you may be surprised to know that most of the universe remains a mystery to us . why is that so ? more than 95% of the universe is made up of dark energy and matter that nobody has been able to understand or study till date .

  DARK ENERGY 

Stars , planets , black boles , asteroids , comets , etc. are only a small fraction of what makes up the universe . based on their observations and studies of these objects , scientists have concluded our universe s in a state of expansion . but if it was only made up of galaxies , stars , planets and other objects that we know about , then it should not be expanding . this contradiction led to the belief that something more – or rather some energy – exists in the universe , which is causing it to expand . this is called dark energy . while not much is known about dark energy , we are sure that there is a lot of it present in the universe . in fact , it makes up 68 per cent of the universe .

 

 

      the dark matter is in the blue colour .

 

·     WHO DISCOVERED DARK MATTER ?

Dark matter originally known as ‘missing mass ’, was first worked out by swiss – American astronomer Fritz Zwicky in 1933 . while studying the mass of stars in the coma cluster of galaxies .  Fritz found that the stars consisted of only about 1 per cent of the mass required to keep the galaxies together . but there was other mass that existed . this was responsible for keeping he clusters together and providing extra gravitational pull required to hold galaxies together , for several years , the mystery of this missing mass was not solved . in the 1970s , Vera Rubin and William Kent Ford ( both American astronomers ) conformed the existence of dark matter by observing the same occurance

 

             

                

 

 

4 . ALL ABOUT GALAXIES

Galaxies are home to stars and other celestial bodies . It was only in the early 20^th century that the existence of galaxies other than the Milky Way was recognized . Before that , early astronomers labelled them as nebulas , since they appeared to look like hazy clouds . galaxies are present in every part of space  , as observed through powerful telescopes . they differ through shape , structure and the level of activities within them .

 

·     WHAT IS A GALAXY ?

A galaxy comprises a large group of hundreds of billions of stars and  intersteller  matter( gas and dust ) bound together by gravity . almost all large galaxies are also believed to have gigantic black holes at their centers . galaxies exist in a variety of shapes and sizes ranging from dim – dwarf sized to bright and massive , spiral shaped ones . almost all galaxies seem to have been formed immediately after the universe came into existence . these beautiful formations are generally found in clusters , some of which form a larger cluster and spam hundreds of millions of light years across the universe . a light year is the distance travelled by light in one year , at a speed of 3,00,000 km/s  

·     TYPES OF GALAXIES

There are three main classifications of galaxies --- elliptical , spiral , and irregular , some spiral galaxies are called “ bared galaxies”

·     ELLIPTICAL GALAXIES

These galaxies are round , oval or more like elongated sphere . sometimes , they may be so stretched that they look like a cigar . These galaxies generally contain many old stars , but not much dust and other interstellar matter . Like the stars in discs of spiral galaxies , their stars also orbit around the galactic center , but in a more disorderly way . not many stars have been known to have formed in elliptical galaxies . The largest known galaxies in the universe are giant elliptical ones which can be as big as two million light years long . The smaller of these galaxies are known as dwarf elliptical galaxies . Virgo A or ( M87 ) is an example of a giant elliptical galaxy found close to the center of the Virgo cluster of galaxies .

     ---- elliptical galaxy …

SPIRAL GALAXIES

Spiral galaxies comprise a flat disc with a bulging center .These galaxies have long

Spiral arms that wind towards the center . the disc comprises  stars , planets , dust and gas , which rotate or spin around the galactic center in a regular manner . at hundreds of kilometers per second . this spinning motion may result in the matter in disc taking shape of a spiral , like a pinwheel .

While many new stars are born in spiral galaxies , the older stars are generally located at the bulging center of the galactic disc . these discs have a halo around them and astronomers believe that they comprise of unknown dark matter .

One type of spiral galaxy is known as “barred galaxies” since the bulge at the center looks stretched like a bar and the spiral arms come out from a group of galaxies known as the local group .

 

   ------ a spiral galaxy ……..

·     IRREGULAR GALAXIES

Galaxies which do not have a distinct shape , such as spiral , elliptical , or lenticular (resembling lenses ) ,are irregular galaxies . irregular galaxies – such as large and small Magellanic  clouds --- are uneven or out of shape as they are generally under gravitational force of other nearby galaxies . since they are packed with gas and dust , irregular galaxies are a fertile ground for the formation of new stars .

5 . THREE’S COMPANY

QUASARS , PULSARS AND MAGNETARS .

There are some celestial objects that are lesser -  known . that is because they are either too far away from us and difficult to study ; they can only be observed under certain conditions ; or because of their strong magnetic fields .

·     QUAINT QUASARS

A quasar ( pronounced kwayser )  is an extremely bright astronomical object similar to a star . it can be a trillion times brighter than our sun ! quasars give off large amount of energy . this energy is derived from gigantic black holes which exist in the center of galaxies where quasars are located . quasars are very bright . while they outshine all other stars in the same galaxy , they cannot be seen by naked eye as they are amongst farthest objects in space . most quasars are larger than our solar system and emit more energy than 100 galaxies combined !

 

·     PULSATING PULSARS

Neutron stars that spin extremely fast and have a regular pulse of radiation or radio waves are known as pulsars or pulsating radio stars . a neutron star is born when the center of a star explodes violently in what is known as supernova . since a neutron star has a solid core and a liquid mantle , it has a magnetic field a trillion times stronger than that of earth’s . it emits high energy beams at both the north magnetic pole as well as the south magnetic pole . as the neutron star rotates , if at any time the beam points towards earth it appears to turn on and off , to pulsate ! we can therefore conclude that all pulsars are neutron stars , but all neutron stars are not pulsars .

 

A pulsar is like a lighthouse . although it’s light is shining all the time , we can only see the beam of light when it points directly in our direction . similarly , a beam of light from a pulsar can be seen intermittently only when it crosses our line of vision .

 

· MAGICAL MAGNETARS

A magnetar is another kind of neutron star . we know that regular neutron star has a magnetic field trillion times stronger than earth . the magnetic field of a magnetar is additionally 1000 times stronger . magnetars are the most powerful magnets in the universe . it is said that if a magnetar come as close as 966 kilometers to earth it could possibly suck out iron from our bodies !

 

 

6. AMAZING ASTEROIDS

Besides the planets , the moon , and the stars , there are several smaller celestial objects in space called “ small bodies ” . these include asteroids ,  meteoroids and comet.

·     WHAT IS AN ASTEROID ?

An asteroid is a small , rock – like object which orbits the sun , just like planets , but unlike planets , asteroids are much smaller , they are sometimes called minor planets .

A majority of several hundred thousands of asteroids in our solar system are found in the asteroid belt , it is a region between Leonids and Jupiter . some asteroids are also found in orbital path of planets like earth .

 

·     WHERE DID ASTEROIDS ORIGINATE FROM ?

Asteroids are leftover pieces from the time when the solar system was formed around 4.6 billion years ago ! the solar system began with the collapse of a huge  cloud of gas and dust , which condensed to form the sun , planets , and their moons . asteroids are the remains in the asteroid belt that never made it to the sun , nor they could transform into planets or any other celestial bodies .

 

·     ARE ALL ASTEROIDS IDENTICAL ?

Asteroids are different from each other and were created in different places and at different distances from the sun . most have a sharp and an uneven shape . some asteroids are hundreds of kilometers in diameter , but many are the size of a small stone . asteroids are made up of various types of rocks , clay or metal , like nickel and iron . they provide important information regarding our planets and the sun .

7. METEOROIDS , METEORS , & METEORITES

Meteoroids , meteors , & meteorites are all related to “ shooting stars ” we sometimes see streaking across the night sky . we call the same celestial object by different names , depending on where they are . 

WHAT ARE METEOROIDS AND METEORS ? 

When one asteroid bangs into another , it may break into pieces . these pieces are called meteoroids . a meteoroid is a small rocky or metallic natural object that enters earth with great speed , there is a resistance ( or drag ) of the air on the rock which heats it up .

 As it falls and comes closer to the earth and passes through our atmosphere , it starts to vaporize ( becomes gaseous ) , and a streak of light is seen , which is the hot air left behind by the burning piece of rock . this is a meteor , a streak of light in the sky . meteors are not really stars , but due to their appearance and streaks of light , they are also known as “ shooting stars ” ! meteors are sometimes confused with comets due to the light they both seem to emit . however , comets are made up of ice and

dust not rock .

 

                                                                                                                 

·     METEORITES

Most meteoroids get vaporized by the time they enter earth’s atmosphere , however , some of these rocks do not disintegrate , instead they reach the surface of the earth and are known as meteorites . most meteorites are the size of a small pebble , but some rare ones can also be the size of a large boulder . since meteorites originate from asteroids , they are useful to scientists , who can gain more information about these ancient rock – like objects .

 

  ITS RAINING METEORS !

When many meteors fall on the earth at the same time , it is called as a meteor shower . meteors fall at a speed which is 32 times faster than that of a speeding bullet .

A meteor shower is generally named after the constellation the appears to be coming. Scientists have estimated that there are nearly 21 meteor showers that occur annually . listed below are some of the major meteor showers , their constellations , and the months  when they can be viewed .

Quadrantids (  bootes constellations ): December / January .

Lyrids ( lyra constellation ) : April

Perseids ( Perseus constellation ) : August

Orionids ( Orion constellation ) : October

Leonids ( Lyra constellation ) : November

Geminids ( Gemini constellations ) : December

8 . CAPTIVATING COMETS

People sometimes confuse a comet with a meteor . however , they are both different in their composition . besides , unlike a meteor , comets can be viewed even when they are very far from earth 

·     WHAT IS A COMET ?

Comets , also known as ' dirty snowballs ' or ' icy mudballs ' , are a part of our solar system , and are typical icy bodies covered with dark organic material . like asteroids and planets , they also orbit the sun .

However , comets have a very long orbit . when a comet orbits too close to the sun , the ice and the dust begin to get destroyed or vaporized , this creates a cloud of comet dust particles around the heart or nucleus of the comet and is known as coma. The  vaporized ice and dust form the tail of the comet . the tail glows due to the light from the sun . and is visible to human beings on earth.

                  

 

9.AMAZING CELESTIAL ODDITIES

BLACK HOLES AND AURORAS

 

The mysteries of universe are unending . here are two more that are mindboggling;

One is the blackest object to be found in the deep space , and the other is a celebratory vibrant show of lights seen on earth !

·  WHAT ARE BLACK HOLES ?

 What can be darker the space itself ? well the darkest objects to be found in the depths of our universe are also some of the weirdest and strangest things -- black holes ! a black hole is an area with such tremendous gravity or pull that nothing can escape -- not even light -- can escape from it . usually black holes are formed when a star dies . when the fuel in a star gets depleted or finished , it starts to disintegrate and cave in on itself , resulting in a huge bang . all the matter remaining after the explosion -- which is much , much more than the mass of the sun -- falls into a really tiny point -- this point where a large amount of mass is trapped is called a singularity. It has a huge impact even though its small .

 You can imagine a black hole as a circle with a singularity in the center . the gravity in this center is so great , that it sucks in everything , including light . that is why black holes appear so black ! a black holes surface is known as its event horizon that defines the boundary where the velocity needed to escape the hole exceeds the speen of light.

·     WHAT CAUSES AURORAS ?

Auroras are mostly seen during the night , bit they are effects created by the sun . besides the heat and the light , the sun is responsible for sending small particles and a lot of other energy . earth's magnetic field protects us from this energy and particles .

 Auroras are caused by charged particles that travel between the sun and the earth along the magnetic fields . a magnetic field is an area of influence of a magnet . it covers the whole area in which the attraction or repulsion of a magnet can be felt . magnetic fields such as that of earth cause magnetic compass needles and other permanent magnets to line up in the direction of the field .

 Sometimes due to solar winds and storms , the amount of energy sent by the sun varies . during one particular type of solar storm , called the coronal mass ejection , the sun ejects a large bubble of electrified gas which can travel at great speeds through space . when a solar storm like this approaches the earth , the energy and small particles move down into earths atmosphere along the magnetic field lines at the north and the south pole .

 When the particles reach the atmosphere , they engage with the gases in it , and this results in , amazing displays of bright light in the sky . dazzling green and red lights are seen due to the interactions with oxygen , whereas nitrogen gives off blue and purple hues .

 

     

9. CONCEPTS ABOUT THE UNIVERSE

Cosmology is the scientific study of the evolution of the universe . cosmologists are interested in understanding the past , present and the future of the universe . for centuries human beings have been trying to understand the cosmos . early concepts about the universe were vastly different from modern day theories and have undergone several changes . 

·     EARLY CONCEPTS OF THE UNIVERSE

Greek philosopher and scientist Aristotle ( 384 - 322 ^BCE ) was one of the greatest scholars of the western world . he proposed that the earth was the center of the universe , with the sun , the moon , and the planets.

 

 

 Jr Sci. Aashvi gujarathi

Batch 0020

Class - 5