OUR SOLAR SYSTEM – At A Glance

Major Constituents Of Our Solar System

  Our solar system is the collection of heavenly bodies that encircle round the sun. It is located on the outer fringes of the Milky Way Galaxy. It includes:

1. The sun,
2. The Nine planets and their satellites ,
3. Asteroids,
4. Meteors,
5. Comets and
6. Drifting particles called inter planetary dust and electrically charged gases called plasma.

The Sun

The Sun is one of more than 100 billion stars in the giant spiral galaxy called the Milky Way. It accounts for 85 % mass of the solar system. The gravitational force created by the huge mass of the Sun keeps other objects (planets) travelling around it. The sun continuously gives off energy in several forms – visible light, invisible infrared, ultra-violet, x-rays, gamma rays, radio waves and plasma. The glowing surface of the sun, which are see, is called ‘photosphere’.

Solar prominence: The sun emits streams of substances mainly hydrogen in all directions. These are called prominence which send huge bouts of incandescent material upward from the sun’s surface. When these eruptions roll out of the atmosphere for many miles, they are seen as solar flares.

Solar winds:  President  streams of protons blowing out of the corona and sweaping over the whole solar system are called solar winds. They are made up of plasma, ionised gas.

Plages & Sunspot: Changes continuously occur on the surface of the sun . Bright spot called plages  and dark  spots  called  sunspot frequently form and disappear. Sunspot appear dark because they are cooler by about 15000 C than the surface of the sun. These sunspots show strong magnetic fields and reach a maximum every  eleven  years. They affect global atmosphere and climate and interrupt radio communications.

Aurora Borealis/Australis: Aurora Borealis or northern lights and Aurora Australis or southern lights are multi-colored lights that sweep across the sky in weaves and are visible in the Arctic region and Antarctic region respectively. The Earth’s magnetic poles attract the electrified particles coming from the sun. These electrified particles cause gases in the upper atmosphere, or more appropriately the magnetosphere, to vibrate in glow in colors.

PLANETARY WORLD

   Under the impact of sun’s gravitational force, all the nine planets revolve round the sun, in a an elliptical orbit . The planets in order from the sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto .

• The planet, except  Venus  and  Uranus , also rotate anticlockwise at their axes.
• The planets except  Pluto  on the basis of their characteristics may be classified into :
• Terrestrial (earth- like ) planets  or  inner planets which have denser material. Planets in this category are Mercury , Venus , Earth and Mars.
• Jovian planets (Jupiter-like) or outer planets which are gaseous , gigantic with large satellite  families  and high  rotational velocities. These are Jupiter, Saturn, Uranus and Neptune.
• The largest terrestrial planet is earth while the smallest jovian planet is Neptune.
• The planets in the descending order of their sizes are Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars,  Mercury and Pluto.
• Planet mercury and venues have no satellites.
• Planet closets to the earth is Venus. After that come the Mars, Mercury, and Jupiter.

Mercury

     Mercury the innermost planet has the fastest orbital motion (48 km/s ) in compliance with the kepler’s laws and the shortest period of revolution, 88 days. This fast speed keeps it from being drawn into the sun’s gravitational field. The planet has a created surface, much like our moon’s and has no atmosphere. It is characterized by the maximum diurnal range of temperature.

Venus (The Veiled Planet)

Diameter – 12112 km. Relative mass — 0.820 (earth = 1) polar flattening – 0.0 (% ) Inclination of axis — 177.2⁰  Number of known satellites – 0

     Venus, the closets planet to the earth , is  also called earth’s twin because of its similar size, density and mass. It is suitably named for the goddess of beauty and love as it is second only to the moon in brilliance in the night sky and is popularly known as Evening star or morning star. The Venus is shrouded with a thick cloud cover and its atmosphere consists primarily of carbon di-oxide (90-95 %). The planet is considered as the hottest one and it has slowest rotational velocity also.

Earth (The Blue Planet)

Diameter – 12742,  Inclination of axis : 23⁰  27’, polar flattening : 0.3 %

        The earth the densest and fifth largest planet of the solar system is having such temperature ranges that water can exit here as solid, liquid and gas. This has made possible the evolution of life forms on this planet.

Mars (The Giant Planet )

Diametre — 1, 43, 000 km , Relative mass – 318.0 (Earth = 1) Polar flattening – 0.5 % inclination of axis – 25⁰12’ known satellites – Phobos and Demos.

        Mars appearing as a reddish ball, has evoked greater interest than any other planet because of presumption of possibility of life on it. The angle of inclination and period of rotation is nearly the same as that of earth. Hence    mars has season much like the earth. There is evidence not only of stream action  here but of catastrophic flooding too.

Jupiter ( The Giant Planet )

Diameter – 1,43,000 km , Relative mass – 318.0 ( Earth = 1), Polar flattening – 6.5 % , Inclination of axis – 3⁰5.’

       This giant planet 1300 times greater volume than  the earth’s but it is composed most of gas and liquid swirling in complex patterns. Its atmosphere consists largely  of hydrogen and helium which accounts for the low density of the planet. Jupiter has the fastest rotational velocity among the planets. Since, Jupiter has no solid surface hence there is no record of geologic history. Its satellites are however, solid bodies. The largest of its over 100 known satellites are Io, Europa, Ganemede and Callisto which are called Gaillean satellites. Ganemede is the largest satellite of the solar system and is almost the size of earth.

Saturn ( The Ringed Planet )

  Diameter – 1, 21,000 km Relative mass – 95.20 (Earth =1 ) Polar flattening – 10.5% Inclination of axis – 26⁰44’

         The unique feature of this second largest planet is its spectacular system of seven rings, identified  by the letter ‘A’ to ‘G’  ( though not in an alphabetical order). These rings discovered by Galileo, are made up of individual moonlets of varing sizes. Saturn has the biggest family of satellites, a total of eighteen or more. Titan, the largest  satellite , is the  only one in the solar system with an atmosphere of its own. Saturn has the least density among all the planets.

Uranus (The Green Planet)

    Diametre — 47,000 km, Relative mass – 14.6 ( Earth = 1 ), Polar flattening – 7.0 % , Inclination of axis  — 97⁰55’, Number of satellites – 5.

       This chilly  methane planet is unique in the sense that its axis of rotation lies only eight degrees from its orbital plane. Therefore its rotational motion has the appearance of …….. , unlike other planets which spin on their axis.

Neptune

Diameter – 45,000 km Relative mass – 17.3 Inclination of axis – 28⁰48’.

        Uranus and Neptune come most closely if any two planets in the solar system can be considered twins. A part fresh being, attributable to the methane in their atmosphere. Neptune’s atmosphere contains an earth sized blemish called the Great Dark Spot. It has eight tiny satellites, ton being the largest.

Pluto (The planet X) – Why Excluded From Our Solar System?

   Diameter – 2,330 km surface temperature – 230⁰ C Number of satellites –1 

       Its not included in our Solar system anymore for a variety of reasons. The farthest, smallest, darkest and the coldest planet, Pluto was first discovered by P. Lowell only by mathematical calculations who accordingly named it as planet X. Its satellite, Charon, is nearly half its size due to which Pluto appears like a bi-planet. NASA using a improved telescope has shown that Pluto is shrouded in frozen nitrogen but methane as once thought. The unique feature of Pluto is its orbit – the most eccentric one: at its closest approach to the sun and the farthest, it is 4.4 and fully 7.3 billion kilometers away respectively. Due to this eccentricity, Neptune becomes farthest planet whenever Pluto’s path crosses inside Neptune’s. This was the situation between 1979 to 1999. And now it is Pluto’s turn again for the next 248 years.

See Also

Universe – In A Nutshell

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