Solar System

The sun ,the moon and all those objects shining in the night sky are called celestial bodies. The sun its planets and their satellites the asteroids and the comets together, these all comprise the Solar System.All Stars are luminous , Some million of stars form "Milky Way"it is also called 'Akash Ganga'. The Sun is the nearest star to the Earth.The Sun is a burning sphere of gases the is 1.3 million times bigger than the earth.All the living organisms that exist on the earth derive necessary energy from the sun there are many hypothesis about the origin of the solar system. Among then "planetesimal Hypothesis" put forth by chamberlain and moulton is widely accepted.According to this in the universe when a speeding star passed by the sun it attracted and separated some of the gaseous matter from the sun.The Separated gaseous material,while revolving round the sun,condensed as planetsimals after gradual cooling some of the planetesimals united and formed as the present day planets by attracting each other the heat and light radiation from the sun is called insolation

The concept of sun centerd(or) heliocentric solar system was first laughed at till 400 years ago.Before these theory general view was that earth is at the centre and the sun,Moon and other planets were revolue around the earth.The first four planets closest to the sun the terrestrials are rocky and metallic then next four planets out from the giants are made of helium and hydrogen

SUN

The sun is at the centre of our solar system.Our Solar System is formed about 5 billion years ago and the surface of the sun is 4.6 billion years old. Distance from earth is - 4,95,98,900 Km Diameter of the sun is 13,92,000 km or 109.1 times earth. Rotation Speed is 26 days on average to rotate on its axis at equator and 36 days to complete on rotation at poles (As the sun is made up of different gases so different parts of the sun rotate at different speeds) Surface temperature-5700 &deg C Time taken to reach light from sun to earth is 8min 16.6 sec. Several Solar Missions were sent in to the solar space to study about the sun and it's characteristics. The first detailed observation were made by NASA between 1959 and 1968.In 1980 the Solar maximum mission made a detailed study of solar flares. The Solar and heliospheric observatory (SOHO) launched in1995 has been continously collecting the data about the sun from last decade.The sun is the younger star when it is compared with the other stars in the universe,it is very bright and hotThe sun is made up of huge amounts of hydrogen and helium gases.the nuclear reactions at the centre of the sun emit a large amount of energy these energy makes the sun to glow. All these Energy travel through space these is how we get heat and light.

Mercury

Mercury is the closest planet to the sun it is the Smallest of all the eight planets orbiting the sun at an average distance of 58 Million Km. Its Equatorial radius is 2939.7Km and it moves round the sun at a speed of 30 miles/sec completing it's revolution in about 88 days and one spin on axis is 59Days. The sky of mercury is always dark because mercury has virtually no atmosphere to cause the scattering of light the mercury surface is packed with Craters.The largest crater is the Caloris basin. Mercury has no planets and the atmosphere consist of helium,sodium ,Oxygen and mean temperature is 179 ° C.

Venus

Venus is enveloped in poisonous clouds of sulphuric acid and has hellish climate.It is referred as the morning and evening star because it rises before dawn and sets at sunset . Its called earth's twin.but unlike earth,Venus has no oceans.Venus is the hottest planet with the surface temperature of 486 &degC The temperature is due to the green house effect caused by the heavy atmospher of carbondioxide. It rotates from east to west so if you are in venus the sunrise would take place to the west and not the east.Surface is covered with volcanic rocks and the equatorial radius is 6051Km and the distance from the sun is 108 Million Km and atmosphere consists of Carbondioxide,nitrogen,sulphur dioxide,argon,neon,carbon monoxide and helium.the rotational period round the sun is about 255 days and one spin on axis is 243 days.Venus has the longest day of any planet in our solar system.

Earth

Earth is the only terrestrail planet where life exists this is because of its atmosphere has 78% nitrogen and 21% of oxygen.Presence of water and soil are other essential factors.It receives optimum temperature for life to survive Earth's Satellite is moon .It is slightly flattend at poles that is why it is described as Geoid,Geoid means earth like shaped from the outer space the earth appears blue because it's two-third surface is covered by water there fore called blue planet .Equatorial radius is 6378.14Km and the distance from the sun is 150Million Km and the atmosphere consists of Nitrogen,Oxygen,Carbondioxide,Inert gases with water vapour and the mean temperature is 15 &deg C.one spin on axis is one day.

Mars

The Equatorial radius of mars is 3397.2Km and the distance from the sun is 228 Million Km. It's the Red planet suffering red dust storms that swril at higher than hurricane speed moving at a speed of 25 km/sec Mars is named after the Roman god of wars Martian soil is rich in iron,There fore it is red in colour.Hence the name red planet is given to mar's the martian surface has huge volcanoes and deep canyons the largest volcano olympus mons(mt Olympic )rises to a height of 78,000 feet The mars Odyssey Space craft has detected large Quantities of war in the form of ice close to the north polar surface.Mars has two satellites namely Deimos and Phobos.The atmosphere of mars consists of carbondioxide,Nitrogen,Oxygen,Carbon Monoxide,Ozone,Inert gases with mean temperature of -63 &deg C.one spin on axis is one day.

Jupiter

The atmosphere of Jupiter Consist of Hydrogen and helium and the Equatorial Radius of 1,42,984 Km and the distance from the sun is 778Million Km.one spin on axis is 9 hours 56 min.It's over layers are gaseous composed of hydrogen compounds.There is a ring system around jupiter which is invisible from the earth.The Great Red Spot on Jupiter is a Complex Strom The air is Unbreathable because of the presence of hydrogen,ammonia and methane in the atmosphere.there are no traces of oxygen or water vapour it is a gaseous body it has 16 satellites the first four largest satellites are Callisto,Ganymede,Europa and Lo the mean temperature of jupiter is -125 ° C.

Saturn

The Satrun atmosphere consist of Hydrogen and Helium With mean temperature of -125 C The Distance from the sun is 1427 Million Km, the Equatorial radius of 60,268Km one spin on axis is 10 hr 40min.This isknown as the lord of the rings which are not rings at all but rather orbiting collections of icy chunks,ranging in size from tiny Particle to large particles Saturn has more moons than any other planets there are more than 30 moons.The planet is visible flattened at poles due to very fast rotation.Largest moon are tethys,Dione,Rhea,titana and Lapetus.

Uranus

It is found in 1781 by William Herschel.Uranus appeareas blue-green because of presence of methane gas in the atmosphere which absorbs the infra red rays.Its core is made uo of rocks and ice.It has 21 known moons to largest being Titania and Oberon.Chemical composition is 98% of the upper atmosphere is composed of hydrogen and helium and remaning 2% is methane.In 1977 it was found that the planet has 9 rings similar to those of saturn but are much fainter later in 1986 two more were discovered the equatorial radius of uranus is 25,559Km and the Distance from the sun is 2870 Million Km and the atmosphere consists of HydrogenHelium and Methane.one spin on axis is 17hr 14min.

Neptune

The Equatorial radius of 24,746Km and the distance from the sun is 4497 Million Km and it's atmosphere consist of Hydrogen,helium and Methane with mean temperature of -193 ° C to -153 ° C.It receives about 1/1000th of sunlight we get on earth.Neptune has eight satellites,largest being Triton.It appears Blusih in colour due to the presence of methane in it's atmosphere.Neptune has several dark spots largest spot is the Great Dark Spot,about the size of the earth.It is very cold because to its large distance from the sun.one spin on axis is 16 hr 7min.