THE SOLAR SYSTEM

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THE SOLAR SYSTEM

o   




What is solar system?

o   Planets

•     Mercury
•     Venus
•     Earth
•     Mars
•     Jupiter
•     Saturn
•     Uranus
•     Neptune

o   The Sun

o   The Moon

What is Solar system? ü  The Sun + ü  The Nine Planets (Now 8) + ü  The satellites of the Planets + ü  The Asteroids + ü  The Meteoroids + ü  The Comets + ü  The interplanetary dust + ü  Plasma (The electrically charged gases)

The 8 (9) planets are

ü  Mercury

ü  Venus

ü  Earth

ü  Mars

ü  Jupiter

ü  Saturn

ü  Uranus

ü  Neptune

ü  Pluto

(Note: The planet PLUTO lost the status of a planet in the year 2006. This is announced by International Astronomical Union. Now, the Pluto has been named as a dwarf planet).

According to the new definition given by International Astronomical Union in the year 2006, a planet is a celestial body that v  is in orbit around the sun v  as sufficient mass for its self gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium i.e. nearly round shape v  Has cleared the neighborhood around its orbit

ü  The Planets have no light of their own.

ü  They take the light from the Sun.

ü  All the planets move on their axis from West to East direction.

ü  Venus and Uranus rotate on East to West direction. (Remember this).

ü  The planets revolve around the Sun in elliptical orbit.

ü  Each planet takes different time to complete the orbit round the Sun.

ü  Satellites revolve around the planets.

ü  Jupiter has 63 satellites. (Highest number of satellites for a planet).

ü  Earth has only one satellite i.e. Moon.

ü  Do all the Planets have satellites? ü  No, the two planets that are nearer to the Sun have no planets. ü  They are Mercury and Venus.

ü  Mercury and Venus have no satellites. (These are the first two planets from the Sun).

ü  The Sun is at the center of the Solar system.

ü  The Sun is the largest body in the solar system.

ü  The distance of the Sun from the earth is 150,000,000 km.

ü  The Mercury and the Venus that are near to Sun are called inferior planets.

ü  All other planets are at a greater distance from the Sun than the earth are called superior planets.

Celestial Bodies: v  The Sun, the Moon and all objects that shine in the sky are called celestial bodies. v  They are made up of gases and emit heat and light in large amount. v  These are called stars. v  The SUN is a star. v  The celestial bodies that do not have heat and light and are lit by the light of the stars are called planets. v  The word planet means Wonder. v  Billions of stars put together is called galaxy. v  Millions of such galaxies are called Universe. v  Our solar system lies in the Milky Way v  Earth is present is a galaxy is called Milky Way or Akashaganga. v  Constellations: Group of stars is called constellations. v  The most easily recognizable constellation is the small bear or saptarishi. v  North Star or Pole star indicates the north direction.

Inferior Planets: Mercury and Venus Superior Planets: Mars, Jupiter, Saturn, Uranus and Neptune.he earth are called superior planets.

Inner Planets: Mercury, Venus, Earth and Mars. Outer Planets: Jupiter, Saturn, Uranus and Neptune.

Now let us know more about each planet.

MERCURY:

MERCURY

ü  This is the nearest planet to the Sun.

ü  This is also the smallest planet in the Solar system.

ü  Mercury has no satellites.

ü  The Mercury has no atmosphere.

ü  Mercury is also called inferior planet.

ü  Mercury is one of the inner planets.

ü  The Mercury rotates from West to east direction.

ü  The Mercury takes the least time to complete the orbit round the Sun.

ü  The Mercury completes the orbit in 88 days.

ü  This means 1 year on Mercury is 88 days.

ü  The Mercury has craters.

ü  The longest crater of the Mercury is Carolis Basin.

VENUS:

VENUS

ü  This is the second nearest planet to the Sun.

ü  Venus has no satellites.

ü  Venus is considered to be the Greek God.

ü  The Venus is the nearest planet to the earth. (Remember).

ü  This rotates in the East to West direction. (Uranus also rotates in the East to West direction and the remaining planets in West to East direction).

ü  Venus is considered to be earth’s twin.

ü  Venus is also called inferior planet.

ü  The Venus is one of the inner planets.

ü  This is also called Morning and Evening star.

ü  This is the brightest of all the planets.

ü  Venus is the hottest planet. (The surface temperature is 400⁰ C).

ü  Venus has 98% of Carbon dioxide in its atmosphere.

ü  The revolution of the Venus is faster than the rotation.

ü  Due to this Venus has long day than the years.

EARTH

THE EARTH

ü  This is the 3^rd nearest planet to the Sun.

ü  The earth is also one of the inner planets. (Others being Mercury, Venus and Mars). 

ü  The earth contains 2/3^rd of water. Hence it looks blue from the top.

ü  The earth is called living planet.

ü  This is also called blue planet.

ü  This is the only known planet where the life exists.

ü  This is the only planet with plate tectonic observations. (What is this? We come to know in the later chapters).

ü  The earth has one satellite, the Moon.

ü  The Sun is the nearest star to the earth.

ü  The brightest star near to the earth is Sun.

ü  The “Proxima Centuari” is the brightest star near to the earth after the Sun.

MARS:

MARS

ü  This is also called Red planet.

ü  The red colour comes with the presence of Iron oxide in the soil.

ü  This is one of the inner planets.

ü  This is one of the superior planets. (Others being Jupiter, Saturn, Uranus and Neptune).

ü  The atmosphere contains mostly Carbon dioxide.

ü  The Mars has volcanoes. Tharsis and Olympus mons are the most important volcanoes of the Mars. 

ü  The Mars has two satellites.

ü  They are

ü  Deimos

and

ü  Phobos.

ü  The first spacecraft to visit Mars was Mariner 4 in 1965.

ü    In 2008, Phoenix was sent and it landed in the northern plains to search for water

Asteroids: v  These are also called planetoids. v  These are fragments of planets. v  Asteroids revolve around the Sun. v  Asteroids are present between the Mars and Jupiter. v  Ceres is the largest body in the asteroid belt.

JUPITER:

JUPITER

ü  The Jupiter is the largest planet in the solar system.

ü  The Jupiter has 63 satellites.

ü  The 4 important satellites of the Jupiter are Ganymede, Callisto, Lo and Europa.

ü  The Ganymede is the largest satellite in the solar system.

ü  The Ganymede is larger than the planet Mercury.

ü  The Jupiter is mainly composed of Hydrogen and Helium.

ü  Jupiter is the least rotating planet in the solar system.

ü  NASA (National Aeronautics and Space Administration) sent an artificial satellite called Galileo on to Jupiter. 

ü  The rotation time of Jupiter is 10 hours and this is the shortest of all the planets.

SATURN:

SATURN

ü  This is the second largest planet in the solar system.

ü  The Saturn is distinguished by extensive ring system.

ü  This is also called ringed planet. (This consists of  golden rings around it).

ü  This is also called beautiful planet.

ü  The rings are made up of small ice and rock particles.

ü  The Saturn has 61 satellites.

ü  The two important satellites are Titan and Enceladus.

ü  The Titan is the only satellite with substantial atmosphere.

ü  Galileo Galilei was the first person to turn the Telescope towards the Saturn in the year 1610.

URANUS:

URANUS

ü  This is called the green planet.

ü  This is the coldest planet.

ü  The Uranus has 27 known satellites.

ü  The Uranus rotates in East to West direction.

ü  The important satellites are Titania, Oberon, Umbriel, Ariel, Miranda.

ü  The Titania is the largest satellite of Uranus.

(Note: Only Venus and Uranus rotate in East to West direction. Remaining planets including earth rotate in West to East direction.)

NEPTUNE:

NEPTUNE

ü  This is the farthermost planet from the Sun.

ü  This is the coldest planet.

ü  This has 13 known satellites.

ü  The largest satellite is “Triton”.

THE SUN:

THE SUN

ü  The Sun is also a star.

ü  The Sun is the major source of energy in the World.

ü  The time taken for the Sun rays to reach the earth is 8 minutes.

ü  The Sun is divided into three layers.

·        Photosphere (Outer most layer, the temperature is 6000⁰ C).

·        Chromo sphere (Intermediate layer, the temperature is 32000⁰ C).

·        Corona (The innermost layer, the temperature is  lakh⁰ C).

·        The core of the Sun is 2,700, 000⁰ C.

ü  The Corona is visible during eclipses.

ü  The major gas constituents of the Sun

·        Hydrogen (71 %)

·        Helium (26.5 %).

ü  The Sun accounts for 99.8 percent of the total mass of the Solar system.

ü  The Sun is 109 times bigger than the earth.

ü  The weight of the Sun is 2 * 10 ^ 27 tonnes.

ü  The Sun rotates and revolves.

ü  The Sun rotates on its own axis in 25 days.

ü  The Sun revolves in 250 million years.

ü  The nearest star to the Sun is “Alpha Centauri”. This is located 4.25 light years away from the Sun.

ü  The expansion of the gases away from the Sun is called Solar wind.

ü  The distance between the Sun and the earth is called Astronomical Unit.

ü  Aphelion is the maximum distance of the earth from the sun. This is 152,000,000 km.

ü  Perihelion is the minimum distance of the earth from the Sun. This is 147,000,000 km.  

ü  Quasars: These are the stars that emit more light and more energy.

ü  Pulsars: These are the stars that emit less light and less energy.

ü  Comets: These are formed by dust particles and hot gases. (Halley comet appears every 76 years. It was last appeared in 1986).

THE MOON:

THE MOON

ü  This is the satellite of the earth.

ü  The Moon is the only satellite of the earth.

ü  The Moon revolves round the earth.

ü  The moon also rotates on its own axis.

ü  The diameter of the Moon is 3480 km.

ü  The mass of the Moon is about 1/81th that of the earth.

ü  There is no atmosphere on the moon.

ü  There is also no gravitational pull on the Moon.

ü  The Moon light reaches the earth in 1.03 sec.

ü  SYNODIC MONTH: The Moon’s period of revolution with reference to the Sun is about 29.53 days. This period is called Synodic month.

ü  SIDEREAL MONTH: The Moon’s period of revolution about the earth with respect to stars. This takes about 27 ½ days.

ü  As we discussed the Moon also rotates on its own axis. The time taken by the Moon to rotate on its own axis is also exactly one sidereal month.

ü  The person from the earth always sees the same face of the Moon.

ü  Only 59 percent of the total surface of the moon is seen from the earth.

ü  APOGEE: This is the farthest distance of the Moon from the Earth. This is 407,000 km

ü  PERIGEE: This is the nearest distance of the Moon from the Earth. This is 3, 56, 00 km.

                       

                                               

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