Essay, Paragraph or Speech on “Our Solar System” Complete Essay, Speech for Class 10, Class 12 and Graduation and other classes.

Our Solar System

The solar system is the name given to the collection of heavenly bodies that encircle around the sun.

The sequence of planets ascending to their distance from the Sun—Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. The sun contains over 99.8% of the total mass of the solar system.

All the planets revolve around the sun in the same direction the orbit is elliptical the orbital parts of planets occur within approximately the same plane; thus the solar system has the shape of flat disc.The planets themselves rotate about their axis in the same direction of their revolution around the sun with the exception of Venus and Uranus i.e. they move in counter clockwise direction. With few exceptions satellite system tend to follow the same movements by the longer planets they orbit.

The planets have different composition as indicated by differing densities. The small, dense terrestrial planets such as Mercury, Venus, Earth and Mars have mean densities of 3.8, 4.8, 5.5 and 3.3 respectively. These planets have large quantities of oxygen, silicon and iron. Outer Giant or Jovian planets such as Jupiter, Saturn, Uranus and Neptune have lesser densities. They are composed mostly of hydrogen, helium, ammonia and methane. The term asteroids is applied to a whole series of a very small planets of fragments of planets revolving around the sun between the orbits of Mars and Jupiter.

The sequence of planets according to the size of descending order are : Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, Pluto.

The sun is 109 times bigger than the earth. Its weight 2 x 10′ tons. It surface temperature is 6000°C. The average distance of the sun from the earth is about 150,000,000 kms. The light from the sun reaches the earth in 8 minutes.

Meteors are formed of dust and gas. When in the atmosphere they bum due to friction. Those which completely burn are called meteorites. Those that partially burn and reach the earth in the form of rockets are called meteorites.

Comets are primordial remnants from the formation of the solar system. They have their home in the cold outer fringe of the solar system away from the outermost planet. Here the comets are non-luminous and have no tails and move slowly in enormous orbits around the sun. Sometimes due to gravitational pull of stars, they come out of their orbit. some of them are lost to their solar system, become the brilliant long tailed comets that are visible from earth. The comets consist of three parts (i) a nuclear, (ii) a head, (iii) a tail. A comet may have three kinds of orbit.

(i) Elliptical if the comet approaching the sun does not have enough speed to overcome the sun’s gravity.

(ii) Parabolic, if comet has just enough speed to counter balance of sun’s gravity.

(iii) Hyperbolic if the comet is fast enough to overcome the sun’s attraction. Comets that keep reproaching in the solar system are said to be periodic comets. The parabolic comets are divided into two categories namely the short period group; and the long period group. The short period group has period of less than 2000 years, for example Halley’s comet, which reappears every 76.3 years. The long group have periods going into thousands of years. The Great Comet of 1811 comes back in 3000 years.

The Sun-The Sun is the centre of the solar system. Its size is about 740 times as much as that of all the planets combined. The huge mass of the sun creates the gravity that keep the other object travelling around it in orderly manner. The sun is 32000 light years away from the centre of our galaxy. The sun takes 250 million years to complete one revolution around its axis. This period is called a cosmic year.

The sun is mainly composed of hydrogen and its energy is generated by nuclear fusion into its interior. The sun consumes about a trillion pounds of hydrogen every second. At this rate, it is expected to burn all its stock of hydrogen in about 5 billion years and will turn into giant. The glowing surface of the sun which we see, is called photosphere. Above the photosphere is the chromosphere so called because of its reddish colour. Beyond this layer is the magnificent corona of the sun which is visible during eclipses only. Between the chromophore and the corona, spectro-scopic investigation have identified a distinct very narrow boundary known as the transition region.

The temperature of the photosphere is about 6000°C, that of the chromosphere about 32,400°C and that of the transition region about 324,000°C and that of the corona which extends far into space about 2700,000°C. Chemical composition (by volume) of sun is Hydrogen 81.76%, Helium 18.17%, Oxygen 0.03%, Magnesium .02%, Nitrogen 0.01% and other 0.01%.

Mercury is the planet closest to sun and the smallest. It rotates on its axis in 58.65 days, while it takes 88 days to complete one revolution aroundthe sun. From the earth it can be seen for a short time as an evening star just after sunset or as a morning star just before dawn.

Venus is the highest planet in the solar system, Venus is popularly known as evening star. It is seen in the east in the morning and in the west in the evening. Venus is very hot planet, possibly the hottest of planets. Mars is called Red planet.

Mars has two small satellites, Jupiter is the biggest planet. Its mass is 71% of the total mass of the planets. It has one and a half times the volume of all the other planets combined. It has the primordial atmosphere of the earth hydrogen, methane, ammonia and water from which life originated on earth. Jupiter has 10 satellites.

 Saturn is nine times larger than the earth. It is second largest planet nearer to Jupiter. It has a density of only 0.69 less than that of water. Saturn has 17 satellites. The most spectacular feature of Saturn is its system of rings which is composed of thousand of rippling, operating bands just 100 feet thick.

Earth—The age of the earth as a planet is 4.5 thousand million years. The earth is like spherical globe compressed on the poles and bulging slightly along the equator. This shape is known as oblate spheroid or an oblate ellipsoid. The equatorial diameter of the earth is about 12,755 km. while the polar diameter is about 12,714 km.

 The earth has two motions, namely rotation and annual revolution. The earth rotates on its polar axis once in about 24 hrs. and revolves around the sun once in 365,25 days. While the daily rotation of the earth causes day and night, the annual revolution is responsible for the change of the seasons.

The velocity of rotation on earth axis depending on the distance of a place from the equator. The rotational velocity at the poles is nearly zero. The greatest velocity is found at the equator where the velocity is about 1700 km. per hour.

Earth also revolves around in an elliptical orbit and consequently the distance between the earth and the sun keeps changing,. It is minimum (14700,000 Km) around. Jan 3 when the earth is said to be in perihelion and is maximum (152000,000 km.) around July 4 when the earth is said to be in aphelion.

The latitude of a pole is defined as to distance north or south of the equator, measured as angle. If all places having the same latitude are joined by a straight line, the line thus produced will be parallel to the equator which is at 0° and they are counted up to 90° north and south, the two poles.

 The length of parallels decreases from equator to poles but the distance between them is constant. The parallel of 45° is not half an equator in length. It is parallel of 60° which is half of the equator.

Some important parallels are :

(i) 23 1/2 North —Tropic of Cancer.

(ii) 23 1/2 South—Tropic of Capricorn

(iii) 66 1/2 North—Arctic Circle

(iv) 66 1/2 South—Antarctic Circle.

 Zones between the parallels.

Tropical Zone—Between tropic of Cancer and tropic of Capricorn. It is hot area.

(ii) Temperate Zone—It is situated between 23 1/2° to 66 1/20 in both the Northern and Southern hemisphere Temperate means neither hot nor cold.

(iii) Frigid Zone—It is situated between 66 1/2° to 90° (near in both hemisphere. It is very cold area.

 Longitude—The longitude show the distance of a point east or west of two prime meridian which at 0° and passes through Greenwich Observatory near London. There are 360 longitude and all the longitudinal lines join pole to pole. Lines of longitudes are called meridians. The longitudes is measured from zero degree to 180 degrees either towards the east or towards the west. The west longitudes are considered as positive and east longitudes as negative.

The earth complete one rotation on its axis in 24 hours. There the time required for one degree longitude rotation of the earth is four minutes. As a rule all places eastwards from a reference point have a time ahead and all place westward of it have a time behind.

Standard time refers to an area e.g. a country. It is the time of a centrally located meridian and the same time is conventionally assigned to the whole area or the country. The region concerned is called a time zone. The time zones are so divided that they differ from the Greenwich mean time. The central meridian for India is the longitude of 82°30′ east which passes through Allahabad and the Indian standard time is in fact the local time of this meridian. The Indian standard time is 5 1/2 hrs ahead Greenwich Mean Time. Exactly halfway around the globe from the Greenwich Meridian (i.e. 1800 longitude) is the international Date line—an imaginary line which follows the 180th meridian. If a person crosses this line from east to west he gains one day and vice versa.