Our Solar System
The Universe
The Universe is commonly defined as the totality of everything that exists including all physical matters and energy,the planets,stars ,galaxies and the contents of intergalactic space.
Scientists believe that the universe was born about 14 billion years ago after a gigantic explosion,commonly known as BIg Bang.
Our own galaxy is called the Milky Way and it contains about 300 billion stars and one of these is our Sun Planets and other objects go round the Sun and those make up the solar system with the Sun at the centre.Latest known galaxy is the Dwarf Galaxy.
Stars
Stars take millions of years to form.They begin their lives in Nabulas,Wahich are clouds of gas and dust,Soon the Nabula becomes a hot dense ball,and the centre heats up.This hot core becomes a star,giving out great amounts of heat and energy.
Solar System
The word solar is derived from the Letin word sol,meaning the Sun. the Solar System is the family of Sun.
The solar system comprises the Sun and its eight planets,which are believed to have been developed from the condensation of gases and other lesser bodies.
The Sun is at the centre of the solar system and all the planets revolve around it in elliptical orbit.It is the nearest star to the Earth.
The Sun
The Sun is the largest member of the Solar system.It is made up of intensely hot gases.It provides heat and light to all the planets in the solar system.It takes about a million years for the heat from the centre of the Sun to reach the Sun's surface.However ,once it leaves the surface ,it takes only about 8.5 minutes to reach the Earth.
The Sun is the centre of solar system.
Hydrogen and Helium are the main gases present in the Sun.
It has a surface tempreature of about 6000°C.
It is one of the stars in the Milky Way Galaxy.It takes 224 million years to compleate onr circle(revolution)around the galactic circle(called cosmic year).
Facts About Sun
| A | B |
| Average distance from the Earth | 249598900 km |
| Diameter | 1391980 km |
| Temperature of the core | 15000000°C |
| Rotation Speed | 25.38 days |
| Time taken by Sunlight to reach the Earth | 8 minute and 16.6 sec. |
The Planets
Planets are celestial bodies that are in constant motion around a star.In Greek,the word planets means 'Wanderer'.The Sun has Eight planets that orbit around it.After the sun these planets are the largest celestial bodies in our Solar system.
The oribit of the planets are shaped like flattered circle.These shapes are called ellipses ,so the path are elliptical.Most planets revolve in west-east direction .Besides revolving around the Sun each planet also rotates on its axis.
Some planet have their own Moons or smaller celestial bodies orbiting around them.
1.Mercury
mercury is the smallest planet.It is closest to the Sun.It is also the fastest moving.Its temperature is around 400°C during the day,but drops to about -170°C at night.This is because it has no atmosphere to trap the heat.
2.Venus
Venus is the hottest planet,with a temperature of 475°C even during the night.This is because its atmosphere is 96% carbon dioxide, a gas that traps heat,similar to a greenhouse.It is the brightest planet in the night sky and easy to spot from the Earth.Venus rotates in an east-west direction.
3.Mars
Mars is often referred to as the red planet because of its raddish soil.This planet has many feature in common with our earth,such as an atmosphere with clouds and polar caps that melt partly in summer.
4.Jupiter
Jupiter is the largest of all planets and sometimes shines brighter than any other planet apart from Venus ,because of its giant size.Its diameter is about 11 times more than that of the Earth's.It is a gas giant made up og Hydrogen and Helium, and is civered by a layer of clouds.Its fast rotating movement cause severe storms.
5.Saturn
Saturn is the second largest planet in our Solar system and is known for its rings.Space studies show that Saturn has thousands of thin rings,made up og ice particles varying in size from very small to as big as an iceberg.
6.Uranus
Uranus is the third largest planet,four times the size of the Earth.It is similar to Jupiter and Saturn in composition,but colder because distance from the Sun.Uranus also has thin rings but they cannot seen form the Earth as they are black in colour.
7.Neptune
Neptune,also called the blue giant ,was discovered in 1846 after some mathematical conclusion were made by astronomers.It is so far from the Earth that it can hardly be seen,even with the powerful telescopes. space studies show that it has about 11 Moons and thin rings,similar to those of Uranus.
8.Earth
The Earth is the only planets where life is present.The Earth is surrounded by an atmosphere of Nitrogen,Oxygen and water vapour.It also has layer of ozone,which absorbs some of the damaging radiation from the Sun.Most importantly,the Earth has water.These conditions support life.Besides,our planet has soil.which allows plants to grow.Though the temperatures on the earth vary a lot(-85°C to 65°C)we have more or less constant temperatures between day and night.Our planet is about 149,591,000 km away from the Sun.Therefore it is neither too hot nor too cold and can support life.
The Earth takes 365¼ days to complete one revolution around the Sun.It complete one rotation in 24 hours,resulting in day and night.
The Moon
Our Moon is a natural satellite of the Earth. satellite are smaller celestial bodies which revolve around the larger bodies- generally the planets . as planets move around the Sun their satellites accompany them in their revolution.Satellite may be natural or human made.Human made satellites are sent to space to collects information for scientists.
The moon is about 3,84,400 km away from the Earth.It completes one revolution around the Earth in about 27 days.It takes almost the same time to complete a rotation on its axis.
The Moon has no light of its own.It reflacts the light of the sun. Since the Moon is much closer to us than the sun,it looks almost as big as the Sun.
We can see the Moon in different shapes on different days of the month.These are called the phases of the Moon.
The Moon has no atmosphere and no water.Its surface is covered by hills,valleys and craters.It is the only satellite that is close enough to have allowed human visits and to have been studied through a telescope.
Dwarf Planets
The dwarf planets lie in the Trans-Neptunian region.These include Pluto,Ceres,Eris makemake and Haumea.Pluto was earlier considered to be the smallest planet,but it was classified as a dwarf planet in 2006.
Some Important Facts about Moon
| A | B |
| Distance from Earth | 382200 km |
| Mass (with respect to Earth) | 1:8.1 |
| Ratio of gravitational pull of Moon and Earth | 1:6 |
| Highest Mountain | Leibnitz Mountain 35000 ft |
| Time taken by moonlight to reach Earth | 1.3 sec. |
| Rotation Speed | 3680 kmph |
| Speed of Revolution | 3680 kmph |
| Revolution Period around Earth | 27th days,7h,43 min and 11.47 s |
| Rotation Period | Absence | | |
| Atmosphere part of Moon not visible from Earth | 42% |
| Maximum distance from Earth(Apogee) | 406000 km |
| Minimun distance from Earth(Periqee) | 364000 km |
| Circumference | 11000 km |
Some Important Facts About Planets
| A | B | C | D |
| Biggest Planet | Jupiter | Densest Planet | Earth |
| Biggest Satellite | Gannymede | Fastest Rotation in Solar System | Jupiter |
| Blue Planet | Earth | Morning Star | Venus |
| Green Planet | Uranus | Nearest planet to Earth | Venus |
| Brightest Planet Out side Solar System | Sirius(Dog Planet) | Nearest Planet to Sun | Mercury |
| Closest Star of Solar System | Proxima | Red Planet | Mars |
| Coldest Planet | Neptune | Slowest Revolution in Solar System | Neptune |
| Evening Star | Venus | Slowest Rotation in the Solar system | Venus |
| Farthest Planet from the Sun | Neptune | Smallest Planet | Mercury |
| Planet with maximum number of satellite | Saturn | Smallest Satellite | Deimos |
| Fastest Revolution in Solar System | Mercury | Earth's twin | Venus |
| Hottest Planet | Venus | Only Satellite with an atmosphere like Earth | Titan |
Some Important Facts about The Earth
| A | B | C | D |
| Age | 46 billion years | Mean Surface Temperature | 14°C |
| Mass | 5.9*10*24 kg | Highest Temperature recorded | 58°C,Al-Aziziyah |
| Volume | 1.083*10*24 Litres | Mean distance from the Sun | 149598500 km |
| Mean density | 5.518 kg/lit | Inclination of Polar axis from orbital plane | 23°C min and 59 s |
| Shape | An oblate spheroid or a geoid | Deepest Ocean point | 11034 m,Mariana Trench(Pacific ocean) |
| RAdius of Earth | 6400 km | Time coordinate of Earth | Longitude |
| Total surface area | 509700000 sq km | Temperature coordinate of Earth | Latitude |
| Land area | 148400000 sq km(29%) |
| Water area | 361300000 sq km(71%) |
| Rotation Time | 23 hours 56 minutes and 4.09 seconds |
| Revolution time | 365 days,5 hours,46 minutes and 45 seconds |
| Orbit speed about the Sun | 29.8 kn/second | | |
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