Astronomy
Astronomy is the study of celestial objects (Includes galaxies, stars, Planets) and processes (waves, Rays, Explosions ) and in more generally astronomy is the study of phenomena s that originate outside the natural atmosphere of the Earth
As many questions from this topic have the scope to ask in UPSC Exams and Have asked before.
What is die difference between asteroids and comets?
- Asteroids are small rocky planetoids, while comets are formed of frozen gases held together by rocky and metallic material.
- Asteroids are found mostly between the orbits of Jupiter and Mars, while comets are found mostly between Venus and Mercury.
- Comets show a perceptible glowing tail, while asteroids do not.Which of the statements given above is/are correct?
(A.) 1 and 2 Only
(B.) 1 and 3 Only
(C.) 3 Only
(D.) 1, 2 and 3
An artificial satellite orbiting around the Earth does not fall down. This is so because the attraction Of Earth (2011)
(A.) Does not exist at such distance
(B.) Is neutralized by the attraction of the moon
(C.) Provides the necessary speed for its steady motion
(D.) Provides the necessary acceleration for its motion
The following topics are covered in this article
- Universe and galaxies
- Solar system
- Layers of sun
- Artificial sun concept
- Planets
- Composition
- Important Satellites
- And other aspects
- Earth
- Earth & Moon
- Latitudes and longitudes of the earth (important ones)
- Time zones
- Eclipses (Lunar and Solar Eclipse)
- Seasons(how seasons formed) and Equinox
- Comets, meteoroids and celestial Bodies
- Black hole and Chandrasekhar Limit
- Bodies law
Universe and Galaxies
Study of universe called cosmology. It comprises billions of galaxies (which are made of millions of stars), Galaxies are classified on the basics of their shape
- Elliptical Galaxy
- Spiral Galaxy
- Irregular Galaxy
Our galaxy to which the earth belongs is milky way (Aakasha Ganga) it has spiral shape and it contains about 300 billion stars in which sun is one star
Universe also contains Planets, Forces, Asteroids, Matter and many more particles and celestial Bodies
The size of solar system is about 105 AU
Evolution of earth is explained by “Big Bang Theory”
Solar System
Sun: It is the center of our Solar System and the major source of Energy for SUN is provided by nuclear fusion reactions where hydrogen is converted into Helium and has temperature of around 6000 degree C
Sun contains three layers, in order from inside SUN to outer Layer
- Photosphere
- Above photosphere is the Chromosphere and
- Last is corona which is visible during Eclipse times
Some other terms related to sun are
- Fraunhofer lines (White and Dark lines of sun)
- Solar winds (Emissions of protons in form of streams)
- Aurora (Particles of solar winds trapped by earths magnetic field called (Aurora Borealis – Northern Region, Aurora Australis – Southern Region))
- Plages and Sunspots (Black spots on the Sun surface are called as Sunspots and Bright Spots are called Plages)
Artificial Sun Concept
To over come the problems of energy insecurity international Community is running a program me i.e called as ITER (International Thermo Nuclear Experimental Reactor) or Artificial Sun Concept Experiments running in southern France near France-Italy Boarder
It was started in the year 2007 contributors are EU, China,Japan,Russia,India,US, South Korea.
EU contributes 46% of total finances.
It is Nuclear fusion Research programme had started in 2007 and the first plasma is expected to come in the year 2020.
Planets
We all now know that there are 9 planets (Now 8 After Pluto dropped out)
Classification of the planets is based on the Type of the materials that the planets have been made
- Inner Planets: (Composed of Solid Particles) : Mercury, Venus, Earth and Mars.
- Outer Planets: (Composed of Gases) : Jupiter, Saturn, Uranus and Neptune.
Mercury:
- It is the closest planet to the sun.it is very hot
- It has no satellites
- Mercury is made out of a large percentage of heavier elements, mainly iron
Venus:
- It is very Bright. 2nd planet from the sun
- It is known as morning and evening star
- It is known as goddess of beauty
- It is very hot because of presence of CO2 in atmosphere
- It has no satellites
- It is tilted at 1770
Earth:
- Has one satellite moon and is the largest among the satellites of terrestrial planets
- It is the only planet which has Life and contains large amount of water in its crust and its core part contain Iron and Silicates
Mars:
- It is Red planet and the red color of Mars is because of Oxidation
- It has two satellites Phobos and Deimos
Asteroids:
- Body of matter which are made of metals and Rocks there are called flying mountains.
- These sizes various from micro to macro
- The largest among them is ceres also called as Dwarf planet
Jupiter
- It is Huge in Size and the 1st member of outer planet
- It has rings but weak and not has bright as the Saturn
- Out of 67 Major satellites of Jupiter are Europa, Calisto and gannymede.
Saturn
- Saturn is known for its specific rings which is very bright and clear
- It has 62 satellites the largest being Titan
Uranus:
- Uranus has blue color because of presence of methane in its atmosphere
- Axis of rotation is inclined at only 97 degrees to its orbital plane
- It has 27 satellites. important are Miranda, Ariel etc
Neptune:
- It is the 8th and last planet of the solar system
- It is fifth giant planet has Greenish appearance.
- Neptune and Uranus are called Twin planets
- Earth and Venus are also twin planets
As we all know that our solar system system contains nine planets earlier and Pluto is excluded from them
For a planet these three requirements defined by the International astronomical Union (IAU) in august 2006 as below
- It needs to be in orbit around the Sun
- It needs to have enough gravity to pull itself into a spherical shape
- It needs to have “cleared the neighborhood” of its orbit
Above 1st and 2nd condition are satisfied by Pluto but failed the third condition.
Pluto:
Pluto considered as dwarf planet or Plutoids, the other Plutoids are Eris, Make make etc.
Kuiper Belt:
It is called grave yard of solar system or the outer space of solar system.
Earth
Earth has 7 continents and 5 oceans
Continents –
1.) North America, 2.) South America, 3.) Antarctica, 4.) Africa, 5.) Asia, 6.) Australia, 7.) Europe
Oceans –
1.) Pacific ocean, 2.) Atlantic Ocean, 3.) Indian Ocean, 4.) Arctic Ocean, 5.) Southern Ocean
The earth is not perfectly spherical or elliptical in shape due imperfections of the earth that are influenced by gravitational pull of the earth and many other factors.
So we say that earth has Geoid Shape
Moon
- Study of moon is called selenology
- Only natural satellite of the aerth
- Size of moonis 1/4th of the earth
- Gravitational pull of Moon is 1/6th that of the earth
- Mainly silicon, ironmagnesiumetcare found on moons surfaces
Latitudes and longitudes of the earth
Equator:
- Line drawn in the middle of the earth which divides into two equal parts northern hemisphere and southern hemisphere, is called called equator, also called as “Great Circle”
Latitudes
Important latitudes to remember (23 ½ degrees North) Northern Hemisphere (Tropic of cancer).Tropic of cancer passes through India, through 8 states (Highly important for Exams)
1.) Gujarath, 2.) Rajasthan, 3.) Madhya Pradesh, 4.) Chattisgarh, 5.) Jharkhand, 6.) West Bengal, 7.) Tripura, 8.) Mizoram
- (66 ½ degrees North) Northern Hemisphere (Arctic Circle)
- (90 degrees North) Northern poles
- (23 ½ degrees south) southern Hemisphere (Tropic of Capricorn)
- (66 ½ degrees south) southern Hemisphere (Antarctic Circle)
- (90 degrees South) Southern poles
Longitudes
0 degrees longitudes connects North pole and south pole like any other longitudes. It passes throughGreenwich observatory of England that’s why it is called Green which meridian, It is known as prime meridian also because the International Standard Time ISD is calculated from here.
Two capital cities are also located on this
- London –capital of France
- Capital city is Accra –capital of Ghana
All the longitudes converge on the polls and the maximum distance between the 2 longitudes is recorded as the equator. There are 360 longitudes if drawn at the internal of 1 degrees. 0 degrees longitudes divides earth into 2 hemisphere eastern and western hemisphere. In this case each hemisphere has 180 longitudes and 180 eastern and western longitudes as same
Calculation of Time
- Earth covers 360 degrees in 24 hours
- In one hour Earth covers 360/24= 15degrees
- In 4 minutes earth covers =1 degree
- 180 degrees is the Internationla Dead Line
By using the Above theory one can calculate the Time on any part of the earth
Eclipses
Lunar Eclipse :
It is the situation when the Earth comes between Sun and Moon
It occurs only on a full moon day, but it does not occur on every Full moon day, becaause the Moon is so small and the plane of its orbit is tilted about 5 degree with respect to the Earths orbital Plane
Solar Eclipse :
It is the Situation, where the moon comes between Sun and Earth
It occurs only on a new Moon day, But it does not occur on every new Moon day, because of the inclination of the Moons orbital plan
Seasons and Climate
Comets, Meteoroids
Comets:
Are the body of matter revolve around the sun when approaches the sun its outer layer is evaporated and it forms tail, the glowing face of the comet is called coma
There are 2 types of comets
The comets which have life span of 100 years, these originate from kuiper belt
Comets originate from kuiper belt which have life span more than 1000 years
Meteoroid :
A small rock or the debris in the space
Meteor : The meteoroid that burns in the atmosphere
Meteorite : Meteoroid that reaches the earths atmosphere
Black hole and Chandrasekhar Limit
There is upper limit to to the mass of stars above which 2 things are possible
- Explosion of the star to form neutron stars called Pulsar
- Collapse and Compaction of the star to form Black Holes
There fore black holes are formed due to collapse and compaction under gravity at the end of the life cycle
A Indian Physicist Chandrasekhar had predicted an upper limit to the mass of stars which is called Chandrasekhar limit beyond this the star collapses.
The Chandrasekhar limit is the mass above which electron degeneracy pressure in the star’s core is insufficient to balance the star’s own gravitational self-attraction.
The currently accepted value of the limit is about (2.765 × 1030 kg)
Bode’s Law
Bode’s law states to explain the orbital distance of the planet from the SUN
His Hypothesis is based on planetary sequences
The formula of Bodes or Bodes Law suggests that, extending outward, each planet would be approximately twice as far from the Sun as the one before
The hypothesis correctly anticipated the orbits of Ceres (in the asteroid belt) and Uranus, but failed as a predictor of Neptune’s orbit and has since been discredited further. It is named for Johann Daniel Titius and Johann Elert Bode.
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Astronomy – The study of all Universe, Celestial Bodies, Galaxies and all the meteoroids and comets etc ?
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