THE UNIVERSE

The universe consists of planets,stars etc. Mercury, venus, earth, mars, jupiter, saturn, uranus,

neptune, and pluto are the main planets that we have learnt.

The sun is the only celestial body that emits light. With the help of a telescope we can observe other

celestial bodies like uranus,neptune,comets,meteoroids,asteroids,

galaxies,dwarf planets billions of stars and other gaseous objects.

Mercury,Venus,Earth and Mars are called solid planets while jupiter,saturn,uranus and neptune are called gaseous planets.

THE PLANETS

MERCURYMercury is the second smallest of the planets and is also the closest to the sun. It completes its orbit in a much shorter span of time than the other planets. As a result it takes only 88 earth days to go around the sun.However, it rotates very slowly, in about59 earth days. Surface temperatures vary between -180oC to +430oC.

VENUSVenus is identical to the earth in size, so it is often called the ‘earth’s twin’, but it is too hot to support any life. It has a suffocating atmosphere of sulphuric clouds and acid rain. This makes it the hottest planet. Like Mercury, it also has no moon. Venus takes 243 days to rotate and about 225 earth days to move around the sun. A day on Venus is, therefore longer than a year ! Moreover, its rotation is ‘retrograde’, that is, in the opposite direction to that of the earth’s. That is why the sun rises in the west and sets in the east when we see it from Venus.

EARTHThe Earth is the only known planet with suitable temperature, oxygen and water which together make life possible. It takes 365 days and 6 hours to complete one round of the sun and moves on its axis once in 24 hours. It has one moon. The earth is the fifth largest planet in the solar system. Unlike other planets which are rich in carbon dioxide, the Earth’s atmosphere is rich in nitrogen and oxygen.The earth is approximately150 million km away from the sun.

MARSMars is the ‘Red Planet’. It is so called because there is a rust like coating on its surface soil that is often blown into great storms. Astronomers thought that life was possible here, but the ‘Viking’ space probes that visited it in 1976 proved it otherwise. It has two moons. The planet rotates around in a little over 24 1/2 hours. Mars takes nearly twice as long as the Earth to complete one revolution around the sun (687 days), in July 1997 NASA’s Pathfinder landed on Mars and began sending very clear picture of the ‘Martian’ environment. As a result Americans plant on land human beings on Mars before the year 2020 A.D. They now know that the Red Planet has a thin carbon dioxide atmosphere with frozen icecap. The southern cap consists of carbon dioxide, but the ice cap in the north is made up of frozen water.

JUPITERJupiter is the largest planet – one and half times the size of all the planets put together. It revolves around the sun once in nearly 12 years. It spins faster than any planet, once in 9 hours and 55 minutes. It is made up of hot liquid hydrogen, helium, methane and is enveloped by frosting clouds. Jupiter can be distinguished from the other planets by its circular light and dark bands and the satellites that circle around it. It has a spectacular Great Red Spot, which is actually a big storm that has existed on its surface for centuries.

SATURNSaturn takes over 29 and a half years to revolve around the sun. It turns around on its axis just a little slower than Jupiter. It is the second largest planet and is a ‘gas giant’. It has more than 18 moons. Thousands of rings of dust and sparkling ice encircle the planet and make a pretty sight.Jupiter,Saturn,Uranus and Neptune also have rings.

URANUSUranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus (Ancient Greek: Οὐρανός), the father of Cronus (Saturn) and grandfather of Zeus (Jupiter). Though it is visible to the naked eye like the five classical planets, it was never recognized as a planet by ancient observers because of its dimness and slow orbit. Sir William Herschel announced its discovery on March 13, 1781, expanding the known boundaries of the Solar System for the first time in modern history. Uranus was also the first planet discovered with a telescope.

NEPTUNENeptune Is The Eighth And Farthest Planet From The Sun In The Solar System. It Is The Fourth-largest Planet By Diameter And The Third Largest By Mass. Neptune Is 17 Times The Mass Of Earth And Is Somewhat More Massive Than Its Near-twin Uranus, Which Is 15 Times The Mass Of Earth But Not As Dense. On Average, Neptune Orbits The Sun At A Distance Of 30.1 Au, Approximately 30 Times The Earth–sun Distance. Named For The Roman God Of The Sea, Its Astronomical Symbol Is ♆, A Stylized Version Of The God Neptune's trident.

PLUTO

Pluto, Formal Designation 134340 Pluto, Is The Second-most-massive Known Dwarf Planet In The Solar System (After Eris) And The Tenth-most-massive Body Observed Directly Orbiting The Sun. Originally Classified As The Ninth Planet From The Sun, Pluto Was Recategorized As A dwarf Planet And Plutoid Due To The Discovery That It Is Only One Of Several Large Bodies Within The Kuiper Belt. Like Other Members Of The Kuiper Belt, Pluto Is Composed Primarily Of Rock And Ice And Is Relatively Small: Approximately A Sixth The Mass Of The Earth's Moon And A Third Its Volume.Charon,Eris and

ceres are newly grouped dwarf planets.

The Moon

The Moon is the only natural satellite of the Earth,  and the fifth largest satellite in the Solar System. It is the largest natural satellite of a planet in the Solar System relative to the size of its primary, having a quarter the diameter of Earth and 1⁄81its mass. The Moon is the second densest satellite after Io, a satellite of Jupiter.

Milky way galaxy.

The Milky Way is the galaxy in which Earth is contained. This name derives from its appearance as a dim "milky" glowing band arching across the night sky, in which the naked eye cannot distinguish individual stars. 

Comets

A comet is an icy small Solar System body (SSSB) that, when close enough to the Sun, displays a visible coma(a thin, fuzzy, temporary atmosphere) and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. Comets have been observed since ancient times and have traditionally been considered bad omens.The tail of the comet is seen in the opposite direction of the sun.

THANK YOU.