The giant family of the sun including planets, asteroids, comets etc is called the solar system. Solar system is composed of the sun and the heavenly bodies in the gravitational field of the sun. The diameter of the solar system is 1.87 light years.
The sun is a medium-sized light yellow colored star whose diameter is about 1392000 km and is situated at about 2.5 × 104 light years away from the galactic center of the Milky Way. The distance between the sun and the earth is about 1.5 × 108 km. About 75% of the total mass of the sun is made up of hydrogen and slightly lesser than 25% of the mass is made up of helium and the rest is composed of carbon, oxygen, and other elements. The temperature of the surface of the sun is 6 × 103 oC and that of the core is 1.5 × 107 oC. The mass of the sun is about 2 × 1030 kg. It takes 2.5 × 108 years to complete one revolution around the galactic center ad that period is called one cosmic year.
The sun is made up of three layers: Photosphere, Chromosphere, and Corona. Photosphere is the central hottest and thinnest layer. The chromosphere is thicker than photosphere and is visible only during the total solar eclipse. Corona is the thickest layer which is spread about millions of kilometers around the chromosphere. The sun produces most of the energy by nuclear fusion on its core.
Importance of sun in solar system:
Planets are the heavenly bodies that revolve around the sun in their own separate elliptical orbits. In the solar system, there are eight planets and out of them, the first four planets which are present inside the asteroid belt are called inner planets. They are Mercury, Venus, Earth, and Mars. But the remaining four planets are out of the asteroid belt and are called an outer planet. They are Jupiter, Saturn, Uranus, and Neptune.
A brief description on each planet is as follows:
|S.No.||Name of Planet||Mean distance from the Sun||Diameter (km)||Temperature (oC)||Period of Rotation||Period of Revolation||Number of Satellite||Mass (Earth = 1)||Atmosphere|
|1.||Mercury||5.8 × 107||4880||427oC at day and -170oC at night||59 days||88 days||0||0.056||Nil|
|2.||Venus||1.08 × 108||12104||480oC||243 days||225 days||0||0.815||90-95%, CO2, clouds of H2SO4|
|3.||Earth||1.5 × 108||12756||22oC||About 24 hrs.||About 365 days||1 [Moon]||1||N2 (78%), O2 (21%), CO2, H2O etc.|
|4.||Mars||2.26 × 108||6720||20oC at day and -143oC at night||24 hrs. and 37 mins||687 days||2 [Phobos, Diemos]||0.1||Thin CO2, little water, little O2|
|5.||Jupiter||7.68 × 108||140800||-150oC||about 10 hrs. [9hr. 55 mins]||About 12 yrs.||67 [Europa, Io, Callisto]||318||H2, He|
|6.||Saturn||1.5 × 109||120585||-180oC||10 hr. 14 min||29.5 yrs.||62 [Titan]||95||H2, He|
|7.||Uranus||2.87 × 109||51200||-216oC||17 hr. 8 mins||84 yrs.||27 [Miranda, Ariel, Umbrial]||15||H2, He, CH4|
|8.||Neptune||4.48 × 109||48000||-220oC||16 hrs.||164 yrs.||14 [Triton, Neried]||17||H2, He, CH4|
|S.No.||Characteristics||Name of Planet|
|1.||Nearest planet to sun||Mercury|
|2.||Farthest planet to the sun||Neptune|
|3.||Fastest rotating planet||Mercury|
|4.||Morning and evening star||Venus|
|6.||Green planet or living planet||Earth|
|9.||Planet having ring||Saturn|
|10.||Planet that can float in water||Saturn|
The International Convention of International Union of Astronomers (IUA) held on 2006 in Prague of Czech Republic has removed Pluto from the list of planets and introduced a new term, Dwarf planet for it. A new definition of the planet has been given by the convention. According to it:
- A planet should have its own orbit around the sun.
- It must be in round shape.
- It must have a fixed neighborhood with other planets.
Satellites are the heavenly bodies that revolve around the plants. They may be natural or artificial.
|S.No.||Planet||No. of Satellite|
|4.||Mars||2 [Phobos and Deimos]|
|5.||Jupiter||67 [Europa, Io, etc.]|
|6.||Saturn||62 [Titan, etc.]|
|7.||Uranus||27 [Miranda, Arial, etc.]|
|8.||Neptune||14 [Triton, Nereid, etc.]|
The piece of rocks revolving around the sun between the orbits of Mars and Jupiter are known as asteroids. It varies in diameter and there are about 200 asteroids are present in the solar system. They are also known as minor planets or baby planets or planetoids. They are composed up of various rocky and metallic substances. Juno, Vesta, Hermas, Eros, Pallas, etc. are some of the asteroids present in the solar system. The Ceres is kept in the group of Dwarf Planet and Pallas is the biggest asteroid with a diameter of 532 km.
A frozen chunk of gas, dust, and ice which begins to resemble a foggy star with a long shiny tail when it approaches the sun is known as comet. The comet can be divided into three parts: nucleus, coma, and tail. The nucleus is made from frozen gases, ice, and dust. When it approaches the sun, the outer layer of nucleus starts to evaporate, which is known as coma. The nucleus and coma combine is said to be head of a comet. When it approaches nearer to the sun, pressure from the solar wind elongates the coma, the elongated part of comet said to be tail of the comet. It is always pointed away from the sun. As the orbit of the comet around the sun is highly elliptical, sometimes it has to pass very close to the sun and sometimes very far from the sun. They are non- luminous bodies, which appear bright by reflecting the light of the sun, so they are termed as tailed stars.
Halley's Comet is a very common comet discovered by an English astronomer, Edmond Halley in 1682 AD. Name and revolution period of some other comets are given below:
|Comets||First Seen (AD)||Revolution|
|Temple- tutle||1366||33 years|
|Schwasman- Washman||1972||15 years|
|Shoemaker- Levi||1993||Collided in 1994 AD in Jupiter|
|Hyakutake Comet||1996||20000 years|
Small pieces of rocks or metals which enter the earth's atmosphere from outer space with very high speed are called Meteors. They are also called the falling star or shooting star. Usually, meteors are burn from the height of 7 km to 120 km and during this, the time velocity of meteors is about 70 km/s. We can see the meteor showers in the sky of the north and south poles.
If meteors are too big, then it will not burn completely and reach on earth, which is called the meteorite. They form a crater on the surface of the earth. It can be mainly classified into three types: Stony, Irony, and Stony- Irony. Stony meteoroids have more silica whereas irony meteoroids have more iron and magnesium. Stony- irony meteoroids have silica and iron both in a balanced amount.
The largest meteorite found in Hoba West near Groofontein, in South West Africa, weighs about 60000 kg and is still at the original spot where it struck the earth. It is named Hoba. About 35000 kg, moderately weighing meteorite, is in the American Museum of Natural History in New York City and was discovered in 1894 AD by Admiral Peary in Greenland. A meteorite that formed a crater of 1265 m in diameter and 174 m in depth fell at Arizona of America, about 50000 years ago.
A group of heavenly bodies where sun is the center and all the other heavenly bodies are under the influence of its gravitational force is called the solar system. The solar system contains of the sun the nine planets, their satellites, a large number of asteroids, comets and meteors.
The sun mainly contains of hydrogen gas. The hydrogen atom continuously combines to form helium atoms. Four hydrogen atoms combine to form a helium atom by the process of nuclear fusion. During this nuclear fusion a huge amount of energy is released. 1H1+1H1→ 1H2 1H2+1H1→ 1H3 1H3+1H1→ 1H4+ energy
Fragments of heavenly bodies that have irregular shape and revolve around the sun are called asteroids. These asteroids that are also known as minor planets revolve around the sun with their revolving orbit present between the revolving orbits of Mars and Jupiter.
Comet that appears every time after a fixed period of time as it takes a definite time to revolve around the sun is called periodic comet. Halley's Comet is a periodic comet that appears after every 76 years. It last appeared in 1986 and will again appear in 2062 AD. Hyakutake is another periodic comet.
One example of a comet is the Hyakutake Comet. The comet revolves around the sun like planets but the orbit is much larger than those of planet. Because of this reason each comet is seen at a gap of long period.
Comet is a small object with a head and a tail. Head is the main body made up of hard particles of methane, water and ammonia embedded in ice. The tail consists of dust or gas. As the comet approaches the sun, the crystal vaporizes and gas glows in the form of a long tail. When the comet moves away from the sun, the tail shortens due to less heat. This is why the tail of the comet increases or decreases when it goes round the sun.
Meteors are the pieces of heavenly bodies that burn to ashes due to friction on entering the earth's atmosphere. When meteor burns, a part of it reaches the earth's surface before burning completely to ashes. The piece that reaches the earth's surface is called meteorite.
The 5 importance of the sun are as follows:
When meteor falls, it comes in contact with the earth's atmosphere. The friction that results causes the meteor to burn completely to ashes leaving nothing to reach the earth's surface. Comet is a heavenly body that shines brightly when it comes near the sun. Comet is seen with a head and a bright tail because of sun's light. As it does not have its own light, it's not a star.
Three reasons of launching artificial satellite into the space are as follows:
The time interval between two successive occurrences of a specific type of alignment of a planet (or the moon) with the sun and the earth is referred to as ______.
a synodic period.
a sidereal period
The giant family of sun including planets, asteroids , comets etc is called ______.
The biggest asteroid is ______.
The largest circular storm in our solar system is on the surface of ______.
One Jupiter day is equal to ______.
3 hrs 20 min
52 hrs 10 min
9 hrs 50 min
30 hrs 40 min