Astronomy (Universe, Solar system, Planets, Etc)

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

Many questions from this topic have the scope to ask in many competitive Exams.

Question from Exam SSC and UPSC

What is difference between asteroids and comets?

1.  Asteroids are small rocky planetoids, while comets are formed of frozen gases held, together by rocky and metallic material.
2.  Asteroids are found mostly between the orbits of Jupiter and Mars, while comets are found mostly between Venus and Mercury.
3. 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)

• 1.)  Does not exist at such distance
• 2.)  Is neutralized by the attraction of the moon
• 3.)  Provides the necessary speed for its steady motion
• 4.)  Provides the necessary acceleration for its motion

Answer: D

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 o   Earth o   Earth & Moon o   Latitudes and longitudes of the earth (important ones) o   Time zones o   Eclipses (Lunar and Solar Eclipse) o   Seasons (how seasons formed) and Equinox o   Comets, meteoroids and celestial Bodies o   Black hole and Chandrasekhar Limit o   Bode’s 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

layers of earth

Sun contains three layers, in order from inside SUN to outer Layer

• ·       Photosphere
• ·       Chromo Sphere
• ·       Corona

Above photo sphere is the Chromo-Sphere and Last is corona which is visible during Eclipse times

                                                                        

Some other terms related to sun are

Fraun-hofer lines (White and Dark lines of sun)

Solar winds (Emissions of protons in form of streams)

Aurora (Particles of solar winds trapped by earth’s 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 overcome 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

Solar System

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 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 earth
• Size of moon is 1/4th of the earth
• Gravitational pull of Moon is 1/6th that of the earth
• Mainly silicon, iron, magnesium, etc are found on moons surfaces

Latitudes, Longitudes and Equator of the earth

Latitudes and Longitudes

Equator:

Line drawn in the middle of the earth which divides into two equal parts northern hemisphere and southern hemisphere, is 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 connect North Pole and South Pole like any other longitudes. It passes through Greenwich 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 degree. 0 degrees longitudes divide 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= 15 degrees
• In 4 minutes earth covers =1 degree
• 180 degrees is the International 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, because the Moon is so small and the plane of its orbit is tilted about 5 degree with respect to the Earths orbital Plane

Lunar and Solar eclipse

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

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 earth’s atmosphere

Black hole and Chandrasekhar Limit

There is upper limit 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

Black Hole

Therefore black holes are formed due to collapse and compaction under gravity at the end of the life cycle

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.