The solar system is the family of the sun, planets revolving around it, the satellites of the planets and the asteroids or meteoroids and comets etc.
There are eight planets in the solar system.
Starting from the sun there are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
All the planets revolve around the sun in their orbits.
Meteorite analysis shows that the age of solar system is about 4530 million years.
The sun is not the largest star of the Milky Way; rather it is an average sized star.
It is not at the centre of the galaxy but shifted towards a side.
The diameter of the sun is 1, 392, 140 km and its mass is 2 * 1027 tonnes.
The outermost layer of the sun is called photosphere, has an average temperature of 5570 0C.
The photosphere rotates at a rate of 25.38 days per turn.
At the centre of the sun hydrogen is undergoing nuclear fusion reaction which provides energy for the heat and light so sun.
The planets of the solar system as well as the moons get light and sometimes heat from the sun.
The four inner planets of the solar system are called terrestrial plants because of their rocky nature.
The outer planets are called gaseous planets because they don’t have solid surface and are composed of gases.
Planets And Their Characteristics:
Its distance from Sun is 58 million kms.
Its revolution period is 88 days.
Its rotation period is 58 days, 15 hours and 30 minutes.
It has no moon.
It is the nearest planet to the sun.
It is also the smallest planet of the solar system.
It is the fastest planet.
Its radius is 2,433 kms and diameter is 4,878 kms.
It is covered with holes called Craters.
It has no atmosphere.
The temperature on mercury vary between 420 0C (7900F) in the day and -180 0C (-2900F) at nights.
Apart from the moon, Venus is the brightest object in the sky. Venus can be seen with naked eye in the morning or in the evening. Following are the main characteristics of the Venus.
Its distance from the Sun is 108 million kms.
Its revolution period is 224.7/225 days.
Its rotation period is 243 days and 14 hours (longest day)
It has no moon.
It is the nearest neighbour of the earth in the solar system.
It is the brightest planet.
It is also the hottest planet.
Its diameter is 12,102 kms.
It is wrapped in thick clouds of CO2 gas.
It rotates from east to west as opposite to most other planets.
The earth is the largest and the densest of the four terrestrial planets. It is the most wonderful planet of the solar system. Following are the features of the Earth.
Its distance from the Sun is 150 million kms.
Its revolution period is 365 ¼ days.
Its rotation period is 23 hours, 56 minutes, 40 seconds.
It has one moon.
It is the densest planet.
It is also the watery and bios planet.
Its diameter is 12756 km (7927 miles equatorial and 7900 miles polar diameter)
It has atmosphere which contains 78% Nitrogen, and 21% Oxygen.
Its two-thirds surface is covered with oceans.
The earth’s surface is rich in Oxygen, Silicon, Aluminium, Iron, Calcium, Sodium etc.
Distance form sun 228 million kms.
Revolution period 687 days.
Rotation period 24 h, 37 min and 22 sec.
It has two moons Phobos and Deimos.
Its diameter is 6794 kms.
Mars is covered with red dust.
It has an atmosphere composed almost entirely of CO2.
Its average temperature is -53 0C.
Its distance from sun is 778 million kms.
Revolution period 12 years.
Rotation period 9h, 50min, and 30 sec. (smallest day)
It has 63 moons.
It is the largest planet of the solar system.
It has the largest number of satellites.
Its diameter is 1, 24,800 kms.
Its diameter is eleven times greater than the earth’s diameter.
It has a dense, cloudy atmosphere of hydrogen and helium.
It has a rock-iron-ice core about 15, 000 km (9,000 miles) thick.
Jupiter radiates 67% more heat than it receives from the sun. this is mainly due to dissipation of the primordial heat of the planet.
In 1610, Galileo became the first person to look at Saturn through telescope.
Distance from Sun 1427 million kms.
Revolution period 30 years.
Rotation period 10h, 14 mins.
It has 62 moons.
The largest moon of Saturn is the Titan and it is the second-largest moon in the solar system. Titan is larger than the planet Mercury.
It is the second largest planet.
It has a magnificent system of rings.
Its diameter is 1, 20, 000 km.
When sky is very dark and very clear Uranus can be seen with the naked eyes. The planet was discovered by William Herschel in March 1787.
Its distance from Sun is 2869.9 million kms.
Revolution period is 84 years.
Rotation period is 16h, and 10 mins.
It has 27 moons.
Titania is the largest moon of Uranus.
It has an atmosphere which is dominated by hydrogen and helium.
Its diameter is 52, 400 km.
Neptune was discovered by the German astronomer Johann Galle.
Distance from Sun 4496, 6 million kms.
Revolution period 165 years (largest year)
Rotation period 18 hours.
Neptune has 13 moons that we know of. The largest moon is Triton.
It is the coldest planet.
It is the slowest to move around the sun.
Its diameter is 49,100 kms.
It is known as the twin of Uranus due to their similarity of size, mass and composition.
Short Note (Solar System)
The partial or complete obscuration of light of moon for an observer on the earth is called lunar eclipse.
Lunar eclipse takes place when the earth comes in position between the sun and the moon. In this way, the shadow of the earth is cast on the moon and the moon does not get sunlight in this position.
Lunar eclipse occurs only when there is full moon. But this does not happen on every full moon because of inclination of the axis of earth to its orbit.
Solar eclipse occurs when the moon comes in between the Sun and the earth and its shadow is cast across the face of the earth.
The solar eclipse occurs when the moon moves to a position between the Sun and the Earth. During this process it throws shadow on the earth. This shadow is categorized in umbral and penumbra. The people who are in the umbral region are unable to see the sun at all. This condition is known as the total eclipse of the sun. While the people in penumbra region can see the sun partly this is known as the partial eclipse of the sun.
This happens with the new moon when the moon is in conjunction with the sun. this does not happen at every new moon because of the inclination of the orbit of the moon to the orbit of earth around the sun.
Asteroids are also known as planetoids. These are small, irregularly shaped rocky objects which orbit the Sun between the orbits of Mars and Jupiter. Asteroids are also known as the minor planets.
Basically the word Asteroid means “Starlike”. Ceres asteroid was the first to be discovered.
Meteorites are small chunks of iron and rock thought to be resulted from collisions between asteroids. They also may be formed when comets disintegrate into fragments. Meteorites enter the earth’s atmosphere and become a meteor. A meteor is a “falling star” that is usually seen in the sky at night. A meteor will burn up from frictional heating as it enters the atmosphere. Most of the meteors burn up before they reach the earth. If they do not reach the ground they become meteorites. Meteorites can be seen at a distance of 70 miles from the earth. Meteorites are heavy objects which weigh about 60 tons.
Comets are those bodies which revolve round the sun. they are mainly composed of ice and dust. Most comets have three parts which are as under.
i) A solid centre.
ii) A head or round coma, that surrounds the centre and consists of dust particles mixed with frozen water, frozen methane and frozen water, frozen methane and frozen ammonia.
iii) A long tail of dust and gases that escape from the head. Most comets stay near the solar system.
Other characteristics of comets are as under:
Comet is usually about 10 km or 6 miles across.
Comets are usually made up of ice and dust.
Millions of comets are present in the solar system.
Halley’s comet is the famous example.
Comets usually move around the sun in the elliptical orbits.
The distance travelled by light at speed of 186,000 miles per seconds in one year is known as a light year. One light year is approximately 9461,000 million kilometres or 5875000 miles. Light year is also used to measure the distance between the galaxies.
The distance between the Sun and the Earth is called as Astronomical Unit. This unit is also used in the measurement of distances between the heavenly bodies within the solar system. The earth is one A.U away from the Sun and the Pluto is 39 A.U away from the Earth.
Black Hole is a hypothetical region in space which has a big gravitational pull for which no matter or radiation can escape from it. Even it is believed that light cannot escape from it. Black Hole usually likes at the centre of galaxy.
A Super Nova is an exploding star. At the end of its phase as a Red Giant, a heavy star explodes as a Supernova shining briefly as brightly as a thousand million stars. Recent Supernova was observed on the night of Feb 23, 1987. This occurred in Large Magellanic Cloud.
Nebula is derived from a Greek word which means “Cloud”. In the sky there are clouds like objects, which are classified as Nebulae. There are both luminous diffuse nebulae and dark obscuring nebulae over the Milky Way. They are made up of dust and gases.
Aurora or Kutub-i-Raushani is a luminous meteoric phenomenon of electrical character seen in Polar Regions with a tremulous motion and giving forth streams of eight Aurora. It is generally believed that the aurora is actually caused by radiation from the Sun-spots.
Solar wind is the stream of electrically charged particles especially protons and electrons, which are emitted by the Sun, predominantly during solar flares and sunspots activity. Some of these particles become trapped in the Earth’s magnetic field forming the outer Van Allen radiation belt, but some penetrate into the upper atmosphere where they congregate in narrow zones in the region of the Earth’s magnetic poles producing aurora displays.
Cosmic Rays are charged particles moving as fast as the speed of light. Most of the particles are protons, while some are alpha particles and electrons. They travel throughout our galaxy, including the solar system and some strike the earth’s atmosphere. They can be detected by instruments on the Earth. Nobody knows how cosmic rays are formed. Some of them are formed by exploding stars or supernova and some come from outside our Galaxy.
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