Universe is the outer space. All things around the earth are called Space. There are billions and billions of stars in the universe. Sun is also a star.
GALAXY
The sun, moon, earth, planets, stars, asteroids, comets all together forms the galaxy.
Galaxies are the largest structures in the Universe.
There are 30 galaxies in outer space, where earth belongs.
Our galaxy is called the Milky Way. It is a spiral galaxy with more than 500 billion stars.
(Andromeda Galaxy is another galaxy near to our Milky Way Galaxy. There are 30other galaxies in our Cluster.)
GRAVITY
Earth also has a pull on us. This force is called gravity.
Gravity is the force of attraction between any two objects.
It is a universal force that keeps everything together.
Gravity holds gases within a star.
It helps Sun to hold all components of the solar system together.
It holds stars in the Milky Way galaxy.
It helps things and Man to remain on the surface of earth.
The force of gravity is strong when the mass is high and distance is low.
Earth pulls all things to it by gravity. Let it be a flying kite or bird. So all things thrown up, comes down. It also helps us to walk on earth.
Gravity in earth is stronger than gravity in moon. So people float. We say, in outer space there is no or little gravity.
Tides in the oceans are caused by gravity force of the moon.
ASTRONAUTS & LIFE IN SPACE
People who go to explore outer space are called astronauts or cosmonauts.
Life in space is different from life on earth. In space there is no air, water or gravity.
Water is taken from earth and once in space all forms of water including sweat and urine is recycled and used. they resort to scrub bathing using soapy towels. All used clothes, crushed food packets and utensils of the disposable type reduce usage of water for cleaning.
Clothes are changed only once in few days. They have printed mission logos on their dress.
Astronauts also carry oxygen to breathe.They have special dress called space suit. It takes 45minutes to put on a 280 pound spacesuit, including the bulky back pack.They are always tied to the space craft to avoid floating. However, weightlessness helps scientists to easily lift heavy objects in space.
Food is precooked as per predetermined and tested menu and are used in powder form form packets directly.
Astronauts work on prefixed timetable controlled from earth!They are provided with morning alarm which is mostly a tune or song selected by their family members ...
In space, Sun rises once in every 90minutes. So they use masks and are tied to their sleeping bags and to each other while sleeping. They are always hooked to their vehicle as they can’t walk steadily.
Water doesn’t flow in weightlessness in space. So they can’t drink water!
Air is used to suck wastes from their body and for flushing. The waste is expelled out to earth.
In space, sound is not heard. So astronauts knock on their helmets to speak, as sound also doesn’t travel in empty space! They use radio waves and wireless phones also. They call home using soft phones.
All astronauts grow tall when they are in space and regain normal height once they are back on earth. However, they have to exercise more than two hours a day to keep themselves fit.(due to lack of gravity, blood flows to head and so bones and muscles become weak...)
In brief, life in space is hard but interesting and needs lot of training. View of earth from space, spirit for adventurous travel in rockets, fame associated with this hard work all attract brillinat students into space....
First Man in space is Yuri Gagarin. (1961, Russia).
First person to walk in space is Aleksei Leonov.(1965, Russia)
First woman in space is Valentina.V.Tereshkova.(1963) She is also the youngest.
Woman who flew more space missions is Shannon Lucid. (more than 5 times).
First paid space tourist is Dennis Tito from US, in 2001.he paid 20 million US dollars.
12 men visited moon. The first was Neil Armstrong. (1961).
STARS
A star is a spinning ball of hot shining gases.
Stars are formed from clouds and dust, which is called a clump. It swirls and condenses. When the heat inside the clump reaches 10 million degree Celsius, protostar is formed. Hydrogen is formed in the core and it burns to form Helium. This emits light that we see. When the Hydrogen gas is finished, core becomes more hot and small. This is called red giant. Helium starts burning in the core. Outer layers are cool. As Helium also gets finished, it bursts. The outer shell is called nebula. The glowing inner core forms a white dwarf, which weakens and diminishes as a black dwarf.
Lifecycle of a star takes billions of years.
Massive big stars form red super giant and on bursting as a supernova, forms neutron stars and black holes.
Star patterns that we see in the sky are called constellations. There are 88 different constellations.
Groups of stars living together are called a cluster.
Hipparchus, an ancient Greek (17-127BC) classified 850 stars according to their brightness.
Star patterns that we see in the sky are called constellations.There are 88 star constellations.
SUN
1. I am round in shape; yellow in colour. I give you light. I am the cause for day and night. Who am I? I am the Sun.
2. Sun gives us light. Plants, animals, human beings- all living things need sunlight for life.
3. Sun gives us lot of energy in the form of light and heat.
4. Sun means “yellow dwarf”. It is a star, smaller than many other stars.
5. Sun looks bigger to us, because Sun is closer to earth than most other stars.
6. Though it looks close to earth, it is 150 million kilometers away from the earth.
7. Sun is enormous. It can hold one million earths inside it. It is 3.3lakh times bigger than earth. There are stars bigger than this!!!
8. Sun being the heaviest star, its gravity is also high. So it can keep 9 planets, their more than 60 moons, and millions of comets and asteroids around it.
9. Sun is a ball of hot gases. The gases are Hydrogen (70%), Helium (28%) and heavy elements.
10. Core of the sun is 15million o C. It’s the innermost part of the sun. The surface of the sun is called Photosphere. It is 6000 o Celsius hot. The surface of the Sun is wavy. Sometimes we can see small black holes on the Sun. These are called Sun spots.
11. The inner atmosphere is called Chromosphere. It is 50000 oC. Corona is the outer atmosphere. It is I million km around the core. We can feel the heat so far down here.
12. Sun is 5 billion years of age. It will live another 5 billion years before it starts to die.
13. Sun spins on its axis. It takes 25days to complete a spin for the centre of the sun, while its ends take up to 36days. This along with the rotation of earth makes us feel that sun rises and sets.
14. The imaginary path of the Sun through the sky is called an ecliptic.
15. Sun rises in the East and we have morning. Sun sets in the West and we have night. So Sun is called the Morning Star.
16. Brightness of the Sun is 380 X 10 24 watts. When a part of Sun taken, the light is equal to 2 lakh 30 thousand candles lighted.
17. Whenever you want to know your direction, stand facing the Sun. Then, side of your right hand is the North.
COMETS
1. Comets are a ball of snow and dust found in the outer space.
2. They are far away from the Sun, beyond the nine planets.
3. These are seen in the outermost part of solar system, called the Oort cloud.
4. There are 10 trillion comets in this Oort cloud.
5. We can’t see them usually. Only when it comes near the sun is it visible.
6. Comet has a head with nucleus and ice called coma. It also has a tail.
7. When a comet comes near the sun, the light rays of the sun fall on it and the nucleus mixes up with the atmosphere. Snow melts. Gas and dust are released. This forms one or two tails which reaches from 150 to 280kilometres.
8. We have studied only 700 comets.
9. Of these, more than 20comets come to earth more often than Hailey’s comet. They are Encke, Hale-Bopp, Temple, etc.
10. Hailey’s Comet is visible once in 76years. This was last seen in 1986.
BIG BANG THEORY
All energy, matter and space were first a small dot. Huge explosion occurred. Universe was formed. It was only a hot, dense mass, without light. About 3 lakh years later, this cooled. Atoms formed. Hydrogen, Helium and other elements were created. Gravity brought these together. It developed into millions of galaxies. In between the galaxies there are lots of empty spaces. Thus, Universe was formed 15 billion years ago.
Scientists who studied about various aspects of the universe are mentioned below.
1 Ptolemy
2 Coppernicus
3 Edwin Hubble
4 Galileo Galilei
5 Aristotle
6 Albert Einstein
7 Issac Newton
8 Arthur Eddington
9 Johannes Kepler
10 Edmund Halley
SOLAR SYSTEM
Sun is the centre of our Solar System. There were formerly 9 planets including Pluto, which has been discarded. It was an ice planet. So now, there are only 8 planets. Of these, 4 planets are terrestrial planets, 3 are Gas Giants and one is a Windy planet.
The terrestrial planets are:
1.Mercury, which is the smallest planet;
2. Venus which is also called the Morning or Evening Star;
3.Mars or the red planet and
4. Earth which takes 365 days, 6hours to go round the sun once. Earth has only one satellite and it is Moon. Earth rotates around its own axis in a day, 23hours and 56minutes.
The Gas Giants are:
1.Jupiter, the largest planet;
2.Saturn or the ringed planet and
3.Uranus or the Father sky.
Neptune is the windy planet. Sun pulls everything to it by gravitation.
Planets and asteroids go round the sun in same direction at different speed.These paths are oval or elliptical in shape and are called orbits.
Aristotle and Ptolemy were the pioneers who studied about our universe. However, it was Nicolaus Copernicus, who suggested that Sun is the centre of our solar system, in 1543. Later in 1610, Galileo Galilei studied about the surface of Moon. This branch of science later came to be known as Space Science.
Light Year:
In space, light travels at a speed of 3 lakh km per second. The distance covered by light in a year is called a light year. Light from moon reaches earth in 1.26 seconds. Light from sun reaches us in 8 minutes 17 seconds. Light from a star reaches earth in 4.22 years….
