Astronomy, Solar System, Nature of solar system,Planetary Movements, No.of Planets, Comets, Eclipses, Constellations, Zodiacal Belt Aries To Pisces
Astronomy, Solar System, Nature of solar system,Planetary Movements, No.of Planets, Comets, Eclipses, Constellations, Zodiacal Belt Aries To Pisces
guide of astronomy |
SOLAR SYSTEM AND IT'S NATURE :
Before our sun explodes, let us have acloser look at our Solar system and the position of our Earth in teh solar system. We will also try to learn about some of the latest infomation gained by mankind about the solar system- including searches for any form of life in the solar system outside the earth.
NATURE OF SOLAR SYSTEM:
The solar system basically consists of our star, sun and planets and other celestial bodies such as satellites of the planets,comets and asteroids. The sun gravitational force acts upon all these bodies and they travel round the sun in various shaped paths or orbits, Satellites orbit round their parent planets, at the same time they also revolve with the planets round the sun.
The word planet is derived from the greek word planet means Wanderer. Our ancients knew of only five planets- Mercury, Venus, mars, Jupiter and Saturn. Since these planets could be seen by unaided eye from earth. The other planets were discovered after the invention of the telescope, Uranus in 1781, Neptune in 1846 and Pluto in 1930.
Apart from these large 9 planets there exists a group of minor planets or asteroids. These mainly lie between the orbits of Mars and Jupiter and vary in dimensions from a few hundred kilometers diameter to just a few centimeters. The first of these smaller planets was discovered in 1801.
A fundamental difference between a planet and star is that a star shines with its own energy whereas a planet shines by reflecting the light which it receives from the star. Satellites also shine by reflecting light which they receive from the central star.
PLANETARY MOVEMENTS:
All planets describe two basic motions. firstly, the rotaional motion, as it moves on its own axis and secondly, the revolutionary motion as it moves in its orbit around the sun.
As seen from earth the plants appear to move across the sky through particular set of constellations. These constellations form what is called the ZODIACAL CONSTELLATIONS. This is because all the planets revolve round the sun in orbits which are approximately in the same plane, like a flattened dish. Only the last planet Pluto has a somewhat steeply inclined orbit.
The planet Mercury and Venus which have orbits, inside the limits of the Earth's orbit are called inferior or interior planets while all the planets which have orbits outside that of the Earth are called superior or exterior planets.
All planets revolve around the sun with different velocities. However as a general rule the orbital velocity decreases outwards from the sun, so mercury revolves fastest and Pluto the lowest.
There is a third type of motion ascribed by planets. But this motion is so small and minute that its effects can be seen only across continuous observation of centuries. This is called the precessional Motion. Precessional motion is causes due to the tilting of the rotation axis of its orbital revolution. All planets and satellites possess their own precessional motions.
No. Of Planets In Solar System :
- First Planet of Solar system is Mercury
- Second Planet is Venus Also called morning or evening Star.
- Third Planet is Earth, The Living Planet
- Fourth Planet is Mars, The Red Planet
- Fifth Planet is Jupiter, the King of planets
- Sixth Planet is Saturn
- Seventh Planet is Uranus
- Eights Planet is Neptune
- Ninth Planet is Pluto
Moon is the Natural Satellite of Earth.
COMETS:
Comets are called dirty snowballs since they consist of a collection of rocky material and dusty ice, which forms the solid part of a comet, called nucleus. When a comet sweeps in near the sun, heat boils off the ice, making a gas cloud. This cloud encloses the comet in a musty cocoon called the coma. The nucleus of a comet may be anywhere from 100km across to less than one km in diameter. But the coma may reach out great distances, sometimes more than even thousands km. As a comet nears the sun , two tails are pushed out from the coma. Each tail is pushes out one part of the tail called the dust tail. This tail is smooth and curved. It has yellow color because sunlight reflects off the dust particles. While the streaming wind from the sun pushes out electrified atoms(ions) from the coma and forms the gas tail. Some of these ions are carbon monoxide and glow with blue light . Because of this pushing action of the sun, the tail of a comet is always kept pointed away from the sun.
A Comet's orbital period is like a planet's year, the time it takes to complete one orbit around the sun. The periods of comets vary from 3.3 years of comet Encke to 76 years of comet Halley. some comets travel through the solar system and do not return for a thousand years or more. They are called periodic comets.
ECLIPSES :
The earth moves round the sun once every year and the moon moves round the earth once every lunar month. these movements of the earth and the moon bring about the most beautiful of celestial phenomena -eclipses. The word eclipse is derived from the Greek word Elkeipses meaning forsaking or disappearance. The eclipses are of 2 two tyeps- solar and Lunar.
A Lunar eclipse occurs when the earth comes in between the sun and moon, which means that the sun,moon and earth lie along a straight line. the sunlight falling on the moon gets cutoff as the moons starts going behind the earth and the earth's shadow falls on moon, thus eclipsing it.
A solar Eclipse occurs when the moon passes between the sun and the earth, blocking the sun's light from reaching the earth's surface.
There may be a maximum of 7 eclipses in a calendar year and some times it may be as few as two. In the year in which there are seven eclipse, five of these may be of the sun and two of the moon. when there are only two eclipses, both of these must be of the sun.
Astronomy, Solar System, Nature of solar system,Planetary Movements, No.of Planets, Comets, Eclipses, Constellations, Zodiacal Belt Aries To Pisces
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