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About Planets Planets are the large celestial bodies which revolve around the sun in closed elliptical paths called orbits. The planets shine because they reflect the light of the sun which falls on them.The easiest way to distinguish planets from the stars in the night sky is that the stars twinkle at night but the planets do not twinkle at night.The planets move around the sun from west to east, so the relative positions of the planets in the night sky keep changing day by day. The planets are very small as compared to the sun or other stars.
There are eight planets in the solar system - 1. Mercury 2. Venus 3. Earth 4. Mars 5. Jupiter 6. Saturn 7. Uranus 8. Neptune
Inner Planets • Mercury,Venus,Earth and Mars are inner planets. They are made of rocks and have metallic cores. They are comparatively small and dense bodies having solid surfaces like our Earth. Earth is the biggest of the four inner planets
Outer planets • Jupiter, Saturn, Uranus and Neptune are called outer planets.The first four outer planets are very giant. They are made of hydrogen and helium gases and not of rock and metal. All the planets revolve around the sun and also rotate on their axis. Some important facts and figures about eight planets of the solar system are given on the next slide.
Some important facts about planets Name of Diameter Distance Time taken to turn no.of Planet of planet from sun once on its axis moons Mercury 4880km 58*106 58 days None Venus 12100 km 108*106 225 days None Earth 12760km 150*106 356 1/4 days 1 Mars 6780km 228*106 687 days 2 Jupiter 142800km 778*106 11 ¾ years 28 Saturn 120000km 1427*106 29 ½ years 30 Uranus 50800km 2870*106 84 years 21 Neptune 48600km 4504*106 165 years 8
Mercury Mercury is the first planet from the earth.During day time the surface of the mercury heats up to 430° but during night the temperature falls up to -180° c due to lack of atmosphere. Mercury has a rocky surface which is covered with craters.Mercury is sometimes visible from earth,just after sunrise or sunset. When mercury is visible just before sunrise in the morning ,it is called “Morning star” and when it is visible just after sunset, then it is called “Evening star”.It can be seen as morning star in the eastern sky in the month September and October or as evening star in the western sky in the month March and April .
Planet mercury show phases like moon. This is due to the fact that the mercury lies in the orbit of the earth. So, as mercury revolves around the sun, its sunlit surface is visible in varying amounts from the earth this produces phases of mercury. Many features of the mercury and Earth’s moon are as follows: 1] Mercury and moon both are nearly of the same size and mass. 2] Mercury and moon both have no atmosphere. 3] Mercury and moon both have rocky surface covered with craters. Mercury and moon both show phases when viewed from the earth.
Venus Venus is the second planet from the earth Venus is slightly smaller than the earth.Venus is a rocky planet. The planet Venus has a dense atmosphere which consists almost entirely of carbon dioxide gas.The cloudy atmosphere of Venus is an excellent reflector of sun light. The planet Venus is the brightest object in the night sky(except the moon).Being quite near to the sun , the planet Venus is very hot .The planet Venus also gets heated excessively by the trapping of the sun’s heat rays by carbon dioxide gas present in its atmosphere which is also called green house effect The maximum temperature on the planet is 480°c.
The planet Venus can be seen as a morning star in the eastern sky or as a evening star in the western sky The venues shows phases like moon. This is due to the fact that the Venus lies inside the earth’s orbit. So, as Venus revolves around the sun,its sun-lit surface is presented to the Earth in varying amounts. This produces the phases of the Venus.Life cannot exist on the planet Venus because it is extremely hot,it has no water and there is no sufficient oxygen in its atmosphere. Mercury and Venus are only two planets which have no satellites or moons revolving around the sun.
Venus Venus
Earth Earth is the third planet from the earth.When viewed from the outer space,the earth appears to be a blue and green ball due to the reflection of sunlight from water and land on its surface .The earth has an atmosphere contains gases like nitrogen,oxygen,carbon dioxide, noble gases ,water vapor and some ozone .
The earth rotates on its axis.It rotates on an imaginary axis which phases which through its north and south pole. The average temperature of the surface of the earth is 15°c The earth has one natural satellite called moon. The two major factors which factors which are responsible for the existence of life on the planet earth are :size of the earth and distance of the earth from the sun.
The motions of the earth • Rotation The earth rotates or spin on an imaginary axis which phases through its north and south poles.The earth completes one rotation on its axis in 24 hours which we call one day. This causes day and night.The earth rotates on its axis from east to west.The axis of rotation of earth is slightly tilted with respect to the plane of its orbit around the sun.
The rotation of the earth causes Day and Night. An important consequence of the rotation of the earth on its axis is that it causes day and night on the earth. As the earth rotates on its axis, first one half of the Earth is turned around towards the sun. This part of earth receives sunlight and has day on it. The part of earth which is turned away from the sun does not receive any sunlight, it remains dark and has night.Almost every 12 hours, a day changes into night, and a night changes into day.The change in the length of a day and night is, however, caused by the tilt of Earth’s axis.
The Motion of the Earth Around the Sun Causes Seasons An important consequence of the revolution of the Earth around the sun is that it causes seasons on the earth such as summer, winter, spring and autumn. Two factors are responsible for causing different seasons on the Earth.These are: 1. Motions of the earth around the sun once every year. 2. Tilt of the Earth’s axis to the plane of its orbit around the sun.
In The Northern hemisphere: 1)It is winter when the earth is closer to the sun. 2)It is summer when the earth is farther from the sun. In the Southern hemisphere: 1)It is summer when the earth is closer to the sun. 2)It is winter when the earth is farther from the sun. Earth has its own satellite (moon)The different views of the moon as seen from the earth are called phases of the moon.
Mars Mars is the fourth planet from the sun.Mars is also called the Red planet because its surface appears red.The red color of Mars is caused by the presence of hydrated iron oxide compound on its soil. Of all of the planets, Mars is most like the Earth.Mars is a rocky planet. Mars has a thin atmosphere as compared to the Earth. The thin atmosphere of mars contains mainly carbon dioxide with small amounts of nitrogen, oxygen, noble gases and water vapour.
Since the planet Mars is very far off from the Sun, so it is quite cold planet. The surface temperature on Mars varies from a minimum of, -87°c to a maximum of 17°c. It has no water. The atmosphere of mars is so thin that it allows the deadly ultra violet rays of the sun to reach its surface.Though no evidence of the existence of any form of life on mars has been found so far but investigations are still going on.Mars has two natural satellites called ‘phobos’ and ‘Deimos’.
Jupiter Jupiter is the fifth planet from the earth.Jupiter is the biggest planet of the solar system.The diameter of Jupiter is 11 times the diameter of the Earth and mass is about 318 times that of the Earth.Because of its very big size, Jupiter can be seen easily in the night sky.Jupiter is made mainly of hydrogen and helium gases. Jupiter has a very deep atmosphere . The atmosphere of the Jupiter consists of helium, hydrogen, methane and ammonia.The surface of the Jupiter is mainly made of liquid hydrogen.
Jupiter is the first of the gas type planets. Below the surface, increasing pressure changes this liquid this liquid hydrogen to solid state.Jupiter appears to be the brightest object in the night sky. Jupiter’s bright appearance is due to the fact that is it has a thick, cloudy atmosphere which reflects most of the sunlight falling on it.Jupiter is a very cold planet, its surface temperature being,-180°c. Jupiter has 28 satellites .It has also some faint rings around it.
Saturn Saturn is the sixth planet from the sun.Saturn is somewhat smaller in size and mass than Jupiter.Saturn is the second biggest planet in the solar system.The distance of Saturn is almost double that of Jupiter The chemical composition of Saturn is very similar to that of Jupiter.Thus, Saturn is made up mainly of hydrogen and helium gases.The atmosphere of Saturn consists of hydrogen, helium, methane and ammonia gases.Saturn has no solid surface.The surface of Saturn is liquid hydrogen.Below the surface is frozen hydrogen.The most distinguish feature of Saturn is the system of colorful rings which surround it.
Three distinct sets of rings of Saturn are visible from earth. Saturn is the only planet with a system of well-developed rings encircling it.The rings of Saturn are made up of tiny particles, all orbiting the Saturn like miniature satellites The rings of Saturn cannot be seen with naked eyes, they can be observed only with the help of telescope.The presence of a well-developed system of rings around Saturn makes it unique in the solar system.Rings have now been discovered around other planets –Jupiter, Uranus and Neptune
Saturn is the most beautiful of all the planets. Being far off from the sun, Saturn is an extremely cold planet.The surface temperature on Saturn is, -180° C. So, no life can exist on Saturn. Saturn has the maximum number of satellites or moons of all the planets in the solar system.Saturn has 30 satellites. the biggest and brightest satellite of Saturn is called Titan. Titan is bigger than the planet mercury.
Uranus Uranus is the seventh planet from the sun.Uranus was the first planet to have been discovered with the help of a telescope.Uranus was discovered with the William Herschel in the year 1781.Though the diameter of Uranus is almost four times that of the Earth, it appears as a small disc through a telescope. This is because Uranus is very, very far off from the Earth.The distance of Uranus from the sun is almost double that of the Saturn.After Jupiter and Saturn, Uranus is the third biggest planet in the solar system.
After Jupiter and Saturn, Uranus is the third biggest planet in the solar system. Uranus is made up of mainly of hydrogen and helium.It is surrounded by a thick atmosphere of hydrogen, helium and methane. Uranus is an extremely cold planet, its surface temperature being,-190°C. It is also surrounded by an atmosphere of poisonous gases.Due to these reasons, no life can exist on the planet Uranus.The planet Uranus has 21 satellites or moons. It has also some rings around it.
Neptune Neptune is the eighth planet from the sun.It lies beyond the Uranus. Neptune is the second planet which is discovered with the help of telescope.Neptune was the first planet to be discovered as a result of predictions. Neptune was discovered in 1846 as a result of the effect of its gravitational pull on Uranus. The astronomers noticed that the planet Uranus was not moving in its orbit around the sun exactly as expected. The Uranus had a slightly,irregular orbit as if ,something, was pulling it out of its orbit due to its gravitational force.
In order to explain the deviation of Uranus from its normal orbit , as an astronomer Le Verrier predicated the existence of another planet beyond Uranus in June 1846. He thought that this distant planet was disturbing the orbit of Uranus due to its gravitational force. By making mathematical calculations,Le Verrier even predicated the mass and size of the unknown planet correctly.Le Verrier asked the astronomers all over the world to search for the new planet with their telescope .Johann Galle discovered this planet in September1846.It was named Neptune.It was Newton's Law of gravitation which formed the basis of Le Verrier’s calculations which led to the discovery of planet Neptune.
The planet Neptune can be seen easily as a tiny blue-green speck even by using the most powerful telescope on the Earth. Neptune is about the same size and mass as Uranus.It is the last of the large planets. Neptune is mainly made up of liquid and frozen hydrogen and helium gases. The temperature of the surface of Neptune is,-200C. No life can exist on the planet Neptune. Neptune has 8 satellites.It has also rings around it.
Although Earth moves around the sun, but it appears from the earth that the sun moves around the Earth against the background of stars.The 12 constellations through which the sun passes during the course of a year are known as the signs of Zodiac.The sun appears in different constellation during different parts of the year.The names of 12 zodiacal signs are given below.The Indian name for zodiacal sings are given in the next slide. Signs of Zodiac
Zodiacal Signs(Rashi) • Capricorn (Makar) • Aquarius (Kumbh) • Pisces (Meena) • Aries (Mesh) • Taurus (Vrish) • Gemini (Mithun) • Cancer (Karka) • Leo (Simha) • Virgo (Kanya) • Libra (Tula) • Scorpio (Vrischak) • Sagittarius (Dhanu)
Thank you Presented by- Anshuma Bharti 8 ‘ c’
