Wednesday, 6 February 2019
The Earth in the Solar System. Geography Chap- 1 for Class 6 << Learners Hobby
STARS
We see countless heavenly or celestial bodies. They are very far from the Earth. These can be starts, planets or their moons. Some of the bright bodies that we see in the sky are stars. They are made up of hot gases. These gases burn and give out huge amounts of heat. All celestial bodies that produce their own light and heat are called stars. They attract other bodies towards them as a result of their huge gravitational pull as a result of their mass. The sun, the centre of our solar system, is also a star. It is the star nearest to the Earth.
CONSTELLATIONS
The stars also form groups. These groups make different kinds of shapes called Constellations.
About 88 constellations have been identified till date. The International Astronomical Union (IAU) assigns the names and boundaries of the constellations.
Most of the constellations are named after mythological figures. Phoenix, Libra and Virgo are southern constellations. One such group is Ursa Major or Big Bear. It is a cluster of seven stars called Saptarishi in Hindi. The large Ursa Major constellation can be seen only in the Northern Hemisphere. The Pole Star which indicates the north direction, always remains in the same position. It can be found with the help of Saptarishi.
GALAXY
In recent years, many systems of star similar to solar system have been discovered. Sun is a star. It shines by its own light and give out enormous heat. Not all the celestial bodies are stars. A huge cluster of stars, clouds of dust and gases is called a Galaxy. It comprises billions of stars. Theere are billions of such galaxies in the Universe.
MILKYWAY GALAXY
The Solar System comprises of the Sun and its eight planets. It belongs to the Milky Way Galaxy or Akash Ganga in Hindi. The Universe is home to all objects, constellations and galaxies.
SOLAR SYSTEM
The Solar System comprises of celestial bodies classified into the Sun and all other bodies going around it. These other bodies going around it.
These other bodies going around the sun classified into:
(I) Planets
(II) Asteroids
(III) Natural Satellites
(IV) Plutoids
(V) Comets
NEW CLASSIFICATION
The International Astronomical Union (IAU) has drawn up new rules for the classification of celestial bodies going around the sun. It states that a planet around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a nearly round shape and has cleared the neighbourhood around its orbit. The celestial bodies are now grouped into three categories:
(i) Planets
(ii) Plutoids and
(iii) Smaller Solar System Bodies.
PLANETS
The planets include Mercury (orbit: 88 days; spin : 59 days), Venus (orbit : 255 days; spin : 243 days), Earth (orbit: 365 days; spin : 1day; moon : 1), Mars (orbit : 687 days; spin : 1 day; moons : 2), Jupiter (orbit : 11 years and 11 months; spin : 9 hours 56 minutes, moons : 63), Saturn (orbit : 29 years 5 months; spin : 10 hours 40 minutes, moons : about 49), Uranus (orbit : 84 years, spin : 17 hours 14 minutes; moons : about 27) and Neptune (orbit : 164 years; spin : 16 hours 7 minutes; moons-13).
Two Groups
All the celestial bodies including the planets going around the sun do not have their own heat and light. They shine by reflecting heat and light of the sun.
Planets as you will observe from the figure above are divided into two groups:
(i) Inner Planets
(ii) Outer Planets
The four inner planets of Venus, Mercury, Earth and Mars are nearer to the sun. On account of enormous heat, some of the gases escape into empty space. The particles of dust are condensed into rocks trapping some gases. The inner planets are rocky planets. The inner planets are rocky planets. The outer planets are made up of gases.
PLUTOIDS
The second category of plutoids includes Pluto and Pluto-like smaller planets like Eris, Ceres and some others - Pluto has not been recognised as a planet because its oblong orbit overlaps with Neptune as can be seen in the diagram above.
OTHER BODIES
The third category of Smaller Solar System Bodies includes asteroids, comets, meteoroids and other natural satellites. The new moons of the planets are discovered almost every year. Their recognition is subject to confirmation by IAU. Planets on the basis of their composition, or in the order of their distance from the sun.
OUR HOME
Earth is our home and is the third planet in terms of its distance from the Sun. It is neither too hot nor too cold to support life as we know it. The spherical-shaped Earth flattens slightly at the poles and bulges at the equator. This shape is known as Geoid. Three-fourth of the Earth's surface is covered with water. This is why it is also called the Blue Planet.
THE MOON
Moon is the Earth's only natural satellite. It is 376,275 km away from the Earth. Its diameter is only one-fourth that of the Earth. Sunlight takes about 8 minutes to reach the Earth, whereas the light reflected by the moon takes about one-and-a quarter seconds only to reach the Earth.
There is no air, water (through Chandrayaan-I has recently discovered some traces of water on moon but its form is still not known) or atmosphere on the Moon. It takes about 27 days to move round the Earth which is about the same time it takes to complete one spin on its axis. As a result, only one side of the Moon is visible to us on the Earth. American Astronaut Neil Armstrong was the first man to set foot on the Moon, on 29th July 1969.
UNIQUE PLANETS
Earth is a unique planet. It is protected against constant bombardment of space debris. Besides being rich in oxygen, the ozone layer of the atmospheric shield does not allow harmful ultraviolet radiation which is reflected back in the form of terrestrial radiation. Earth, however, maintains the balance of this energy. Being the third planet in the Solar System, it is neither too hot nor too cold. Unlike other planets, water is found on the earth in all its three forms - solid (ice); liquid (water) and gaseous (vapour) state.
It is the only planet in the solar system having life on it. Life exists in three forms: animals, plants and microorganisms.
MAN-MADE SATELLITE
Artificial satellites are launched' into space from the earth. These man-made satellites have many objectives like discovery about the universe, communications and other scientific purposes like remote sensing, etc. These space vehicles are launched into space by rockets.
We see countless heavenly or celestial bodies. They are very far from the Earth. These can be starts, planets or their moons. Some of the bright bodies that we see in the sky are stars. They are made up of hot gases. These gases burn and give out huge amounts of heat. All celestial bodies that produce their own light and heat are called stars. They attract other bodies towards them as a result of their huge gravitational pull as a result of their mass. The sun, the centre of our solar system, is also a star. It is the star nearest to the Earth.
CONSTELLATIONS
The stars also form groups. These groups make different kinds of shapes called Constellations.
About 88 constellations have been identified till date. The International Astronomical Union (IAU) assigns the names and boundaries of the constellations.
Most of the constellations are named after mythological figures. Phoenix, Libra and Virgo are southern constellations. One such group is Ursa Major or Big Bear. It is a cluster of seven stars called Saptarishi in Hindi. The large Ursa Major constellation can be seen only in the Northern Hemisphere. The Pole Star which indicates the north direction, always remains in the same position. It can be found with the help of Saptarishi.
GALAXY
MILKYWAY GALAXY
The Solar System comprises of the Sun and its eight planets. It belongs to the Milky Way Galaxy or Akash Ganga in Hindi. The Universe is home to all objects, constellations and galaxies.
SOLAR SYSTEM
The Solar System comprises of celestial bodies classified into the Sun and all other bodies going around it. These other bodies going around it.
These other bodies going around the sun classified into:
(I) Planets
(II) Asteroids
(III) Natural Satellites
(IV) Plutoids
(V) Comets
NEW CLASSIFICATION
The International Astronomical Union (IAU) has drawn up new rules for the classification of celestial bodies going around the sun. It states that a planet around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a nearly round shape and has cleared the neighbourhood around its orbit. The celestial bodies are now grouped into three categories:
(i) Planets
(ii) Plutoids and
(iii) Smaller Solar System Bodies.
PLANETS
Two Groups
All the celestial bodies including the planets going around the sun do not have their own heat and light. They shine by reflecting heat and light of the sun.
Planets as you will observe from the figure above are divided into two groups:
(i) Inner Planets
(ii) Outer Planets
The four inner planets of Venus, Mercury, Earth and Mars are nearer to the sun. On account of enormous heat, some of the gases escape into empty space. The particles of dust are condensed into rocks trapping some gases. The inner planets are rocky planets. The inner planets are rocky planets. The outer planets are made up of gases.
PLUTOIDS
The second category of plutoids includes Pluto and Pluto-like smaller planets like Eris, Ceres and some others - Pluto has not been recognised as a planet because its oblong orbit overlaps with Neptune as can be seen in the diagram above.
OTHER BODIES
The third category of Smaller Solar System Bodies includes asteroids, comets, meteoroids and other natural satellites. The new moons of the planets are discovered almost every year. Their recognition is subject to confirmation by IAU. Planets on the basis of their composition, or in the order of their distance from the sun.
OUR HOME
THE MOON
Moon is the Earth's only natural satellite. It is 376,275 km away from the Earth. Its diameter is only one-fourth that of the Earth. Sunlight takes about 8 minutes to reach the Earth, whereas the light reflected by the moon takes about one-and-a quarter seconds only to reach the Earth.
There is no air, water (through Chandrayaan-I has recently discovered some traces of water on moon but its form is still not known) or atmosphere on the Moon. It takes about 27 days to move round the Earth which is about the same time it takes to complete one spin on its axis. As a result, only one side of the Moon is visible to us on the Earth. American Astronaut Neil Armstrong was the first man to set foot on the Moon, on 29th July 1969.
UNIQUE PLANETS
Earth is a unique planet. It is protected against constant bombardment of space debris. Besides being rich in oxygen, the ozone layer of the atmospheric shield does not allow harmful ultraviolet radiation which is reflected back in the form of terrestrial radiation. Earth, however, maintains the balance of this energy. Being the third planet in the Solar System, it is neither too hot nor too cold. Unlike other planets, water is found on the earth in all its three forms - solid (ice); liquid (water) and gaseous (vapour) state.
It is the only planet in the solar system having life on it. Life exists in three forms: animals, plants and microorganisms.
MAN-MADE SATELLITE
Artificial satellites are launched' into space from the earth. These man-made satellites have many objectives like discovery about the universe, communications and other scientific purposes like remote sensing, etc. These space vehicles are launched into space by rockets.
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