SOLAR SYSTEM | GEOGRAPHY

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SOLAR SYSTEM
 

The solar system consists of the Sun,the eight planets and their satellites and including all the heavenly bodies such as asteroids,comets and meteors.The Sun is at centre and all the heavenly bodies moving around it in elliptical motion.

THE SUN

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THE SUN
 

The most important centre member of our solar system.

SUN STATISTICS

Diameter 1384000 km.
Temperature 60000C at surface.
Distance from Earth 149.8 million km.
Made up of hydrogen–70%,Helium-28%,other 2.5%.
Sun is brightening due to nuclear fusion is taking place.
Sun’s glowing surface is called photo sphere above the photo sphere is the chromosphere.
Sun revolves in elliptical shape.It takes 250 million years to complete one revolution,it is also known as ‘cosmic year’.
The glowing surface of the Sun,that we see is called the Photosphere. Above the photosphere is the red coloured chromospheres and beyond it is magnificent Corona,which is visible during eclipses.
The Sun is continuously emitting streams of protons in all directions either as persistent spiral streams called solar winds or as bouts of incandescent material called Solar Flares.
The constituent particles of solar wind are trapped by the Earth’s magnetic field and enter the Earth’s upper atmosphere as auroral displays, described as Aurora borealis in the Northern hemisphere and Aurora Australis in the Southern hemisphere.
The planet travels with the sun through million of stars in our galaxy at a speed of about 70000 km per hour.
The Sun is about 150 million kms away from the Earth.
Light (at the speed of 300000 km/second) takes about 8.5 minutes to reach the Earth from the Sun.

SUNSPOTS AND SOLAR ACTIVITY

Many photographs of the Sun had taken in white light showing  many dark spots which are called Sunspots.It appears dark by contrast with the solar surface because of having a somewhat Lower Temperature of about 4500 K.It is characterized by intense magnetic fields.

PLANETS

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PLANETS
 

A planet is a heavenly body that moves in an orbit around a star,such as the Sun.
In our solar system there are nine planets.(But Pluto is now not considered in the family of 9 planets).

MERCURY

Mercury is nearest to the Sun.
Rotation 58.65 days.
Revolution 88 days (Fastest in solar system).
It has no satellite.

VENUS

Also known Earth’s twin,Morning star,Evening star.
Brightest heavenly body after Sun and Moon because of (70% albedo).
Closest Planet to Earth.
Hottest planet in our solar system because of 97% Co2.
Slightly smaller than Earth (500 km less in diameter).
Rotates clockwise (backward) unlike others (East to West).
It has no satellite.
Slowest rotation period in our solar system (257 days).
Almost equal rotation and revolution (224.7 days).

EARTH

Earth is the largest of the inner planets.
So Earth is known as the “watery planet”or the “blue planet”due to the presence of huge amount of water on it.
It is third planet from the Sun and the fifth in size.
Earth is the only planet which provides life on it.It has a large quantity of oxygen which supports life.

MARS

Mars is the ‘fourth’ nearest planet to the Sun.
And Mars is also called ‘Red Planet’.
Revolution period:687 days.
Rotation period :24.6 hrs (almost equal to Earth).
It has two satellites-Phobos and Deimos.
It has signs of water.
There is possibility of life.
Various space missions have been sent e.g., Vikings,Pathfinder,Mars Odyssey.

JUPITER

Largest of all planets almost 11 times of Earth.
Called ‘Lord of the Heavens’.
A great red spot (a cyclone) is detected on it.
Fastest rotation time in our solar system is 9.8 hrs.
Revolution 12 yr.
It has 16 satellites (prominent are Europa,Gannymeda and Callisto).
Europa resembles the living condition like of Earth.
Gannymeda is the largest satellite of our solar system.

SATURN

Second largest planet (in size) after Jupiter.
Least density of all (30 times less dense than Earth).
Revolution 29 yr.
Rotation 10.3 hrs.
More than 39 satellites (prominent is Titan).
It has system of ring (3 well defined).

URANUS

Identified as a planet in 1781 by William Hershal.
Rotates from North to South as it is inclined at an angle of 980 to its orbit.
Revolution Period 84 yr.
Rotation Period 10.8 yr.
Like Saturn it is also surround by a system of nine faint rings.
It has 21 satellites (Miranda,Ariel,etc).

NEPTUNE

Appears as ‘Greenish star’ because of presence of ‘Methane’.
Revolution period 165 yr.
Rotation period 15.7 days.
Discovered by JG Galle of Berlin in 1846.
Prominent satellite are ‘Trion and Neroid’.

PLUTO

It is known as Dwarf Planet.
Discovered by CW Tombaugh (USA) in 1930.
‘Smallest planet’ in our solar system.
It is also known as ‘Black Planet’.
Revolution period 248 yr.
Rotation period 6.4 days.
One satellite (Charon ) which is nearly half the size of Pluto.
Now Pluto has lost its status as 9th planet.

ASTEROIDS

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ASTEROIDS

Asteroid or minor planets circle in a broad belt between the orbits of Mars and Jupiter.
It is the debris left over from the formation of inner planets.
Also called ‘Planetoids‘ or small planets.
They are chunks of rock covered in frozen gases.
Too small to retain any atmosphere of their own.
Largest is Ceres (Diameter: 1025 km).
Apophis-asteroid is likely to hare an impact on earth in April 2036.

COMET

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COMET

It is a member of the Sun’s family,part of the solar system.
It travels on a path or orbit around the Sun on a regular schedule.
And has a head and a tail.Its tail originates once it gets closer to the Sun.
May have originated in a huge cloud the ‘oort cloud’ that is thought to surrounded the solar system.
The brightest part of the comet is head corona.
It is made up of solid matter combined with gases.
Hailey comet Reappears after 76 yr.Last seen in 1986.
Comet shoemaker Levy 9 Collided with Jupiter between July 16 and July 21,1994.It provided an opportunity to us to observe the changes because of the collision.A comet becomes visible only when it travels close to the Sun.

METEORS (SHOOTING STARS)

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METEORS (SHOOTING STARS)

They are often seen in sky. Shooting with great speed producing a trail of light.
Meteors are fragments of rock coming towards the Earth,formed due to the Collision of asteroids with one another.
Largest known was of 70 tonnes which landed in Namibia in prehistoric times.

MOON

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MOON
 

The Moon is only satellite of the Earth.
Only 59% of  Moon surface is directly visible from the Earth.
It takes 27 days, 7 hr,43 min and 11.47 sec to complete one revolution around the Earth.
Rotates on its axis in exactly the same time as that in revolution.That is why we see only one side of the Moon.
Circumference 11000 km.
Distance from the Earth 382200 km.
Moonlight takes 1.3 sec to reach on the Earth.
US Astronaut Neil Armstrong and Edwin Aldrin reached Moon on July 21,1969 on Apollo-XI (Landing spot is called ‘Sea of Tranquility’).

PHASES OF THE MOON

Due to its spherical shape,only one half of the Moon gets illuminated by the Sun.
Visible surface of Moon is not the same everyday because it revolves round the Earth.
Visible shape of the Moon are referred to as the phases of the Moon.

  • New Moon This is the phase when the Moon is between the Earth and the Sun and consequently the part of the Moon facing us is in complete darkness.
  • Full Moon This occurs on the 14th day after the new Moon.The Moon at this time shows its fully lighted surface.

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