- Introduction
- Rest time! Have fun
- Physics
- Chemistry
- BIOLOGY
- Reaching the age of Adolescence
- CROP PRODUCTION AND MANAGMENT
- Cells : The basic structural unit of life
- Nutrition in human beigns
- RESPIRATION IN HUMAN BEIGNS
- TRANSPORTATION IN HUMAN BEIGNS
- excretory system in human beigns
- NERVOUS SYSTEM
- PHOTOSYNTHESIS
- Respiration in plants
- REPRODUCTION IN PLANTS
- MOVEMENTS IN PLANTS
- Forest our lifeline
- WASTE WATER STORY
- WEATHER,CLIMATE AND ITS ADAPTATION .
- Reaching the age of Adolescence
- Model tests
- Animation time
Stars & Solar System
Celestial Bodies- The stars, the planets, the moon and many other objects in thesky are called Celestial objects
.Moon-The day on which the whole disc ofthe moon is visible is known as the fullmoon day. Thereafter, every night the size of the bright part of the moonappears to become thinner and thinner.On the fifteenth day the moon is not visible. This day is known as the new moon day. The next day, only a small portion of the moon appears in the sky. This is known as the crescent moon. Then again the moon grows larger every day. On the fifteenth day once again we get a full view of the moon. The various shapes of the bright part of the moon as seen during a month are called phases of the moon.The time period between one full moonto the next full moon is slightly longerthan 29 days.In Night Moon is visible only because of the reflected light rays from sun to us.The size of the illuminated part oft h e m o o n visible from t h e Earth increases each day after the new Moon day. After the full moon day, the sunlitpart of the moon visible from the Earth decreases in size every day.
Stars-Stars are invisible at day due to the bright sunlight. They appear to move from east to west.The movement of stars is due to rotation of Earth from West to East about the axis.Pole Star appears to be stationary in sky as it is situated in the direction of earth's axis.T h e S u n i s n e a r l y 1 5 0 , 0 0 0 , 0 0 0kilometres (150 million km) away fromthe Earth.The next nearest star is AlphaCentauri. It is at a distance of about4 0 , 0 0 0 , 0 0 0 , 0 0 0 , 0 0 0 k m f r o m t h e Earth.
Constellation-The stars forming a group that has a recognisable shape is called a constellation.Constellations were devised by ancient people to be able to recognises t a r s i n t h e s k y . The shapes o f constellations resemble objects familiar to those peopleOrion a another well - known constellation that can be seen duringwinter in the late evenings. It is one ofthe most magnificent constellations inthe sky. It also has seven or eight bright stars.Star Sirius is also located in Orion Constellation.
Sun-The Sun is the nearest star from us. Itis continuously emitting huge amounts of heat and light. The Sun is the sourceof almost all energy on the Earth. Infact, the Sun is the main source of heat and light for all the planets.
Planets-
The planets look like stars, but they donot have light of their own. They merely reflect the sunlight that falls on them.The simplest method of identifying planets from stars is that stars twinkle,whereas planets do not. Also the planetskeep changing their positions wi threspect to the stars.A planet has a definite path in whichit revolves around the Sun. This path iscalled an orbit. The time taken by aplanet to complete one revolution iscalled its period of revolution. The period of revolution increases as the distanceof the planet increases from the sun.
Mercury-(Budh)
The planet mercury is nearest to the Sun. It is the smallest planet of our solar system. Because Mercury is very close to the Sun, it is very difficult to observe it, as most of the time it is hidden in the glare of the Sun. However, it can be observed just before sunrise or just after sunset, near the horizon. So it is visible only at places where trees or buildings
do not obstruct the view of the horizon.Mercury has no satellite of its own.
Venus (Shukra)
Ve n u s i s e a r t h ’ s n e a r e s t p l a n e t a r y neighbour. It is the brightest planet in the night sky. Sometimes Venus appears in the eastern sky before sunrise. Some times it appears in the western sky just after sunset. Therefore it is often called a morning or an evening star, although it
is not a star.
The Earth-The Earth is the only planet in the solarsystem on which life is known to exist.Some special environmental condition are responsible for the existence andcontinuation of life on the Earth. These include just the right distance from theSun, so that it has the right temperaturerange, the presence of water and suitable atmosphere and a blanket of ozone.
Mars (Mangal)The next planet, the first outside theorbit of the Earth is Mars. It appearsslightly reddish and, therefore, it is alsocalled the red planet. Mars has two smallnatural satellites.
Jupiter (Brihaspati)However, the mass of Jupiter isabout 318 times that of our Earth. Itrotates very rapidly on its axis Jupiter is the largest planet of the solarsystem. It is so large that about 1300 earths can be placed inside this giant.
Saturn (Shani)
Beyond Jupiter is Saturn which appearsyel lowish in color.
Asteroids There is a large gap in between the orbitsof Mars and Jupiter . This gap is occupied by a large number ofsmall objects that revolve around the S u n . T h e s e a r e c a l l e d a s t e r o i d s .Asteroids can only be seen through large telescopes.
Comets-Comets are also members of our solarsystem. They revolve around the Sunin highly elliptical orbits. However, theirperiod of revolution round the Sun isusually very long. A Comet appearsgenerally as a bright head with a longtail. The length of the tail grows in sizeas it approaches the sun. The tail of acomet is always directed away from the sun.Many comets are known to appearperiodically. One such comet is Halley’scomet, which appears after nearly every 76 years. It was last seen in 1986.
Meteors and Meteorites-
At night, when the sky is clear and themoon is not there, you may sometimes see bright streaks of light in Sky.These are commonly known asshooting stars, although they are notstars. They are called meteors. A meteori s u s u a l l y a small object t h a t occasionally e n t e r s t h e e a r t h's atmosphere. At that time it has a veryhigh speed. The friction due to theatmosphere heats it up. It glows andevaporates quickly. That is why thebright steak lasts for a very short time.Some meteors are large so that theyc a n r e a c h t h e E a r t h b e f o r e they evaporate completely. The body thatreaches the Earth is called a meteorite. Meteorites help scientists in investigating the nature of the material from which the solar system was formed.
Artificial Satelites-
The artificial satellites are man -made . They are launched from the Earth. They revolve around the Earth much closer than earth’s natural satellite, the moon.
.Moon-The day on which the whole disc ofthe moon is visible is known as the fullmoon day. Thereafter, every night the size of the bright part of the moonappears to become thinner and thinner.On the fifteenth day the moon is not visible. This day is known as the new moon day. The next day, only a small portion of the moon appears in the sky. This is known as the crescent moon. Then again the moon grows larger every day. On the fifteenth day once again we get a full view of the moon. The various shapes of the bright part of the moon as seen during a month are called phases of the moon.The time period between one full moonto the next full moon is slightly longerthan 29 days.In Night Moon is visible only because of the reflected light rays from sun to us.The size of the illuminated part oft h e m o o n visible from t h e Earth increases each day after the new Moon day. After the full moon day, the sunlitpart of the moon visible from the Earth decreases in size every day.
Stars-Stars are invisible at day due to the bright sunlight. They appear to move from east to west.The movement of stars is due to rotation of Earth from West to East about the axis.Pole Star appears to be stationary in sky as it is situated in the direction of earth's axis.T h e S u n i s n e a r l y 1 5 0 , 0 0 0 , 0 0 0kilometres (150 million km) away fromthe Earth.The next nearest star is AlphaCentauri. It is at a distance of about4 0 , 0 0 0 , 0 0 0 , 0 0 0 , 0 0 0 k m f r o m t h e Earth.
Constellation-The stars forming a group that has a recognisable shape is called a constellation.Constellations were devised by ancient people to be able to recognises t a r s i n t h e s k y . The shapes o f constellations resemble objects familiar to those peopleOrion a another well - known constellation that can be seen duringwinter in the late evenings. It is one ofthe most magnificent constellations inthe sky. It also has seven or eight bright stars.Star Sirius is also located in Orion Constellation.
Sun-The Sun is the nearest star from us. Itis continuously emitting huge amounts of heat and light. The Sun is the sourceof almost all energy on the Earth. Infact, the Sun is the main source of heat and light for all the planets.
Planets-
The planets look like stars, but they donot have light of their own. They merely reflect the sunlight that falls on them.The simplest method of identifying planets from stars is that stars twinkle,whereas planets do not. Also the planetskeep changing their positions wi threspect to the stars.A planet has a definite path in whichit revolves around the Sun. This path iscalled an orbit. The time taken by aplanet to complete one revolution iscalled its period of revolution. The period of revolution increases as the distanceof the planet increases from the sun.
Mercury-(Budh)
The planet mercury is nearest to the Sun. It is the smallest planet of our solar system. Because Mercury is very close to the Sun, it is very difficult to observe it, as most of the time it is hidden in the glare of the Sun. However, it can be observed just before sunrise or just after sunset, near the horizon. So it is visible only at places where trees or buildings
do not obstruct the view of the horizon.Mercury has no satellite of its own.
Venus (Shukra)
Ve n u s i s e a r t h ’ s n e a r e s t p l a n e t a r y neighbour. It is the brightest planet in the night sky. Sometimes Venus appears in the eastern sky before sunrise. Some times it appears in the western sky just after sunset. Therefore it is often called a morning or an evening star, although it
is not a star.
The Earth-The Earth is the only planet in the solarsystem on which life is known to exist.Some special environmental condition are responsible for the existence andcontinuation of life on the Earth. These include just the right distance from theSun, so that it has the right temperaturerange, the presence of water and suitable atmosphere and a blanket of ozone.
Mars (Mangal)The next planet, the first outside theorbit of the Earth is Mars. It appearsslightly reddish and, therefore, it is alsocalled the red planet. Mars has two smallnatural satellites.
Jupiter (Brihaspati)However, the mass of Jupiter isabout 318 times that of our Earth. Itrotates very rapidly on its axis Jupiter is the largest planet of the solarsystem. It is so large that about 1300 earths can be placed inside this giant.
Saturn (Shani)
Beyond Jupiter is Saturn which appearsyel lowish in color.
Asteroids There is a large gap in between the orbitsof Mars and Jupiter . This gap is occupied by a large number ofsmall objects that revolve around the S u n . T h e s e a r e c a l l e d a s t e r o i d s .Asteroids can only be seen through large telescopes.
Comets-Comets are also members of our solarsystem. They revolve around the Sunin highly elliptical orbits. However, theirperiod of revolution round the Sun isusually very long. A Comet appearsgenerally as a bright head with a longtail. The length of the tail grows in sizeas it approaches the sun. The tail of acomet is always directed away from the sun.Many comets are known to appearperiodically. One such comet is Halley’scomet, which appears after nearly every 76 years. It was last seen in 1986.
Meteors and Meteorites-
At night, when the sky is clear and themoon is not there, you may sometimes see bright streaks of light in Sky.These are commonly known asshooting stars, although they are notstars. They are called meteors. A meteori s u s u a l l y a small object t h a t occasionally e n t e r s t h e e a r t h's atmosphere. At that time it has a veryhigh speed. The friction due to theatmosphere heats it up. It glows andevaporates quickly. That is why thebright steak lasts for a very short time.Some meteors are large so that theyc a n r e a c h t h e E a r t h b e f o r e they evaporate completely. The body thatreaches the Earth is called a meteorite. Meteorites help scientists in investigating the nature of the material from which the solar system was formed.
Artificial Satelites-
The artificial satellites are man -made . They are launched from the Earth. They revolve around the Earth much closer than earth’s natural satellite, the moon.