Mimas (Saturn's Moon) - (Important Facts) {Part-44}

MIMAS, AT 198km/123mi, a smallest body that can be for its own gravity to caused it to settle into spherical shape.

Mimas

With a very low density, Mimas is largely composed of water ice, with a small quantity of rock.
The most striking feature of the moon is an enormous crater 130km/81mi across, giving it an appearance not unlike the 'Death Star' in the Star Wars movies. This is a coincidence as detailed photos of the moon were only three years after the movie was made.

Enceladus (Saturn's Moon) - (Important Facts) {Part-43}

ENCELADUS IS A GEOLOGICALLY ACTIVE MOON with a patchy surface showing evidence of ancient craters and relatively smooth plains with extensive grooving, the result of tectonic activity.

Enceladus

The Cassini probe discovered that the moon has active volcanoes and plumes of water rich material have been witnessed venting into space from Geysers, ending up in orbit around Saturn as part of one of its rings.

Structure of Enceladus

Although the surface of the moon is largely water ice, it features a large rocky core. Heating of this core by tidal forces and radioactive decay drives geological activity on the moon.
The plumes of water out-gassing from Enceladus have been found to contain salt, suggesting that the water is being heated underground and that it originates from large caverns or even an ocean of liquid salt water.

Plumes of water out-gassing from Enceladus

This discovery makes Enceladus one of the most favourable places in the Solar System to search for life.

Tethys (Saturn's Moon) - (Important Facts) {Part-42}

COMPOSED ALMOST ENTIRELY OF WATER ICE, Tethys is one of the most reflective objects in the Solar System, having been polished by ice particles in Saturn's rings. As the moon is tidally locked, the leading face is brighter due to this polishing.

Tethys

Apart from impact craters, Tethys features a huge chasm, 100km/62mi wide and 3km/19mi deep, that runs nearly three quarters of the way around the moon, 2,000km/1,243mi in length. This is caused by freezing liquids and expanding as the core cooled, cracking the surface.

Diameter comparison of the Saturnian moon Tethys, Moon, and Earth. Credit: NASA/JPL/USGS/Tom Reding

Like most of Saturn's major moons, it was created from the cloud of material left in orbit after Saturn formed.
With a mean radius of 531.1 ± 0.6 km and a mass of 6.1745 ×1020 kg, Tethys is equivalent in size to 0.083 Earths and 0.000103 times as massive. Its size and mass also mean that it is the 16th-largest moon in the Solar System, and more massive than all known moons smaller than itself combined. At an average distance (semi-major axis) of 294,619 km, Tethys is the third furthest large moon from Saturn and the 13th most distant moon over all.

1.3 Major Characteristics of Mughal Administration

Mughal Administration

1. How did the Mughals work?
ans.
- The Mughals upheld the earlier traditions in political and administrative matters.
- The Mughal emperor was a perfect 'Autocrat' and the administration was a 'Centralised Autarchy'.
- The king symbolised the state and was the source and centre of all power agencies.
- The Mughal did succeed in building up a monolithic administration.

2. When compared to the Mauryans, how were the Mughals different?
ans.
- When compared to the Mauryans, the Mughals moved in the direction of greater centralisation.
-They did not pay much attention to social services of health and welfare as well as morals which were areas of special concern for the Mauryan kings.
- But the Mughals had an efficient civil service.
- They recognised merit and accepted Hindu intelligentsia in higher civil service.
- Its only drawback was that it was 'Land-Based' which means it was mainly concerned with revenue functions and was a highly urbanised institution.

Dione (Saturn's Moon) - (Important Facts) {Part-41}

DIONE FEATURES A LARGER ROCKY CORE, accounting for approximately one third of the moon's mass, with the rest composed largely or water ice.

Dione

The moon's surface is heavily cratered though unusually, most of the craters are on the trailing face of the moon, suggesting that at some point in its history, a significant impact spun it 180 degrees, leaving it effectively facing 'backwards' as it orbits Saturn.

.Dione is the fourth-largest moon of Saturn, with a diameter of 698 miles (1,123 kilometres).
 It is the 15th largest moon in the solar system.
Dione orbits around Saturn once every 2.7 Earth-days, at a distance of 234,000 miles (377,400 km), approximately the same distance from Earth to its moon.

Saturn's Moon

The trailing hemisphere of the moon is also riddled with bright ice cliffs, the result of huge tectonic fractures.

1.2 Mauryan and Gupta Administration

Mauryan and Gupta Empires

1. What is Arthashastra, a treatise by Kautilya?
ans.
-  It is a series of books written by a Brahman Minister in the Period of Chandragupta Maurya. Basically it is written in Sanskrit and discusses theories and principles for effective governance.
- It consists of 15 books dealing extensively with the powers and obligations of the king.
- Major organs including the king, the ministers and the Janapada (territory with people settled on it.).
- The Durga, the treasury.
- The Army.
- The Revenue administration.
- The Personnel administration.

2. What are the following principles of Public administration in "Arthshastra"?
ans.
- Welfare orientation.
- Unity of command.
- Division of work.
- Co-ordination.
- Planning.
- Budgeting and accounting.
- Decentralisation.
- Recruitment based on qualification laid down for each post.
- Paid civil services.
- Hierarchy.
- Delegations of Authority.

3. In the Mauryan administration, How the state had to perform?
ans.
- They had to perform two types of functions:-

• The Constituent (Component) functions:- These functions were related to maintenance of law and order, security of person and property and defence against aggression.
• The Ministrant (Welfare) functions:- These functions had to do with provision of welfare aggression.

4. How were these functions (Mauryan) carried out?

ans.

- These functions were carried out by highly organised and elaborate governmental machinery.

5. How was the Mauryan empire divided?

ans.

- The empire was divided into a Home Province under the direct control of central government.

- 4 to 5 outlying provinces, each under a viceroy who was responsible to the central government.

- The provinces had considerably autonomy in the "Feudal- Federal" type of organisation.

- The provinces were divided into districts and districts into villages with a whole lot of officials in charge at various levels.

- There was city government too and two types of courts corresponding to the Modern Civil and Criminal Courts.

5. How was the Mauryan administration work distributed?

- It was distributed among number of departments, a very important department being the special tax department, managed by an efficient and highly organised bureaucracy who was supplemented by the army and the secret police.

6. How was the Mauryan king assisted?

ans.

- The administrative system was a close combination of military force and bureaucratic despotism.

- An outstanding features of Mauryan administration was that the State, through a new class of officials, known as "Dharma Mahamantras" carried out the policy of moral regeneration of the people.

- Ashoka, the great Mauryan king set up a department called the Ministry of Morals.

7. How did the Guptas continued the legacy of the Mauryans?

ans.

- The Guptas continued the legacy of the Mauryans in many respects:-

• The divine character of the king was upheld and king controlled all the levels of the administration machinery.
• The empire was divided, like the Mauryans, for the administrative purposes, into units styled as "Bhakti, Desa, Rashtra and Mandala".
• Villages has their own headmen and assemblies, town and cities had special officers called 'Nagarpatis' and even town councils.
• The king had the help of various functionaries to share the burden of administration.
• Apart from the confidential adviser, there were civil and military officials , district officers and many others.

Rhea (Saturn's Moon) - (Important Facts) {Part-40}

THE SECOND LARGEST MOON IN THE SATURN SYSTEM, Rhea has a composition, appearance and brightness similar to Dione.

Rhea

Around 25% rocky material and 75% water ice, despite its mass giving it the status of the ninth largest moon in the Solar System, it is believed that Rheas's interior is not differentiated. Its structure is a mixture of rock and ice with no defined core.

Like Titan, Rhea has an atmosphere composed of oxygen and carbon dioxide, though it is so thin as to be barely visible. Oxygen in the atmosphere is the result of water ice on Rhea's surface breaking down, but it is not clear where the carbon dioxide originates.

A false colour image of Rhea

1.1 Introduction (Questions and Answers)

1. Which sites are described as Pre-Vedic Period?
- The sites at Mohenjo-Daro, Harrapa and Lothal.

2. During which period, Hinduism first arose?
- Vedic.

3. In which reign, Hinduism took the shape?
- Mauryan reign.

4. What characteristics does the Indian Administration possess in the contemporary world?
- Heterogeneity of goals, ideals, focus and roles. It has reflection of features prevalent in the Ancient Medieval and British Administrative System.

Indian Administration

Titan (Saturn's Moon) - (Important Facts) {Part-39}

TITAN IS THE SECOND LARGEST MOON in the Solar System, the largest moon of Saturn and is the only moon with a thick atmosphere.

Titan

Its radius is nearly 50% larger than Luna, but it has a lower density, giving it a mass and surface gravity that is around 80% of our Moon.

Structure of Titan

The surface is shrouded in an atmosphere that is 98% nitrogen with clouds of methane, ethane and nitrogen-rich organic smog.
In December 2004, the Huygens lander successfully touched down on Titan revealing world that is strikingly similar to our own, but at a much colder temperature.

Huygens in Titan

Featuring seas of liquid ethane or methane shorelines, sand dunes composed of organic material and terrain that has been weathered by methane rains. Titan is also geologically active, with water ice volcanoes and tectonic activity.
Titan's current state is very similar to the young Earth, with the exception of it lacking water vapour in the atmosphere, making it a prime candidate in the search for life.

Iapetus (Saturn's Moon Series) - (Important Facts) {Part-38}

COMPOSED MOSTLY OF WATER ICE, Iapetus'  most striking features is an equatorial ridge, the dark colouring of its leading face and the light colour of its trailing face.

Iapetus

The colours are likely caused by evaporation of water ice in the leading face leaving behind a dark residue.
It is not known how the equator ridge formed or why it runs along the equator of the moon.

Mystery of Iapetus

View of Iapetus

One possibility is that the young Iapetus was spinning faster then it is now, and if it cooled unevenly while slowing down, then the equator could have frozen before the polar regions, which might preserved the flattened spherical shape it had due to the speed of its rotation.

Carboniferous to Permian Periods (Important Facts) {Part-6}

THE CARBONIFEROUS PERIOD (363-290 million years ago) takes its name from the thick, carbon-rich layers - now coal - that were produced  during this period as swampy tropical forests were repeatedly drowned by shallow seas. The humid climate across northern and equatorial continents throughout Carboniferous times produced the first dense plant cover on Earth.

Late Carboniferous Period

During the early part of this period, the first reptiles appeared. Their development of a waterproof egg with a protective internal structure ended animal life's dependence on an aquatic environment.
Towards the end of Carboniferous times, the Earth's continents Laurasia and Gondwana collided, resulting in the huge land-mass of Pangea. Glaciers smothered much of the southern hemisphere during the Permian Period (290-245 million years ago), covering Antarctica, parts of Australia, and much of South America, Africa and India.

• Examples of Carboniferous and Permian Plant Groups:-

Present day-Fir(Abies Concolor)

Fossil of an extinct fern(Zeilleria Frenzlii)

• Examples of Carboniferous and Permian Trees:-

Pecopteris
Group: Maattiaceae ; Height: 4m (13ft)

Paripteris

Group: Medullosaceae ; Height: 5m (16ft 6in)

Ice locked up much of the world's water and large areas of the northern hemisphere experienced a drop in sea-level. Away from the poles, deserts and a hot dry climate predominated. As a result of these conditions, the Permian Period ended with the greatest mass extinction of life on Earth ever.

• Examples of  Carboniferous and Permian Animals:-

s

Skull of an Extinct Synapsid(Dimetrodon Loomisi)

An extinct early reptile-like animal(Westlothiana Lizziae)

Callisto (Jupiter's Moon Series) - (Important Facts) {Part-37}

NEARLY THE SAME SIZE AS MERCURY, Callisto is the third largest moon in the Solar System.

Callisto

It is composed of almost equal amounts of rock, and ice, but is only partially differentiated with no defined core or mantle. It is suggested that the moon grew slowly over a great deal of time by collecting particles that were left in orbit after Jupiter formed.

Structure of Callisto

Because it was slow, heat dissipated so the layers we typically see in other large bodies didn't form.
Callisto's surface is heavily cratered and ancient, featuring no signs of geological activity. It also possesses a tenuous carbon-dioxide atmosphere.

Ocean inside Callisto

A salt water ocean may exist deep within the moon, but conditions for life aren't as favourable as they are on its neighbours, Europa and Ganymede.

Precambrian to Devonian Periods (Important Facts) {Part-5}

WHEN THE EARTH FORMED about 4,600 million years ago, its atmosphere consisted of volcanic gases with little oxygen, making hostile to most forms of life. One large supercontinent, Gondwana, was situated over southern polar region, while other smaller continents were spread over the rest of the world.

Middle Ordovician positions of present-day land-masses

 Constant movement of the Earth's crustal plates carried continents across the Earth's surface. The first primitive life-forms emerged around 3,400 million years ago in shallow, warm seas. The build up of oxygen began to form a shield of ozone around the Earth, protecting living organisms from the Sun's harmful rays and helping to establish an atmosphere in which life could sustain itself.

The Earth during the Middle Ordovician Period

• Examples of Precambrian to Devonian Plant groups:-

A Present day- ClubMoss(Lycopodium sp.)

A Present day Land Plant(Asparagus Setaceous)

Fossil of an extinct land plant(Cooksonia hemisphaerica)

• Examples of Precambrian to Devonian Trilobites:-

Acadagnostus
Group: Agnostidae ; Length: 8mm (1/3 in)

Phacops
Group: Phacopidae ; Length: 4.5 cm

Olenellus
Group: Olenellidae ; Length: 6cm

• Examples of Early Marine Invertebrates:-

Fossil Nautiloid(Estoniceras perforatum)

Fossil Brachiopod(Dicoelosia bilobata)

Fossil Graptolite(Monograptus Convolutus)

The first vertebrates appeared about 470 million years ago, during the Ordovician Period (510-439 million years ago), the first land plants appeared around 400 million years ago during the Devonian Period (409-369 million years ago), and the first land animals about 30 million years later.

• Examples of Devonian Fish

Rhamphodopsis
Group: Ptyctodontidae ; Length: 15cm

Pteraspis
Group: Pteraspidae ; Length: 25cm

Coccosteus
Group: Coccosteidae ; Length: 35cm

Ganymede (Jupiter's Moon Series) - (Important Facts) {Part-36}

GANYMEDE IS THE LARGEST MOON in the Solar System, larger than Titan by just 2%, and is composed of water ice surrounding a rocky mantle and an iron core, ice accounts for almost half the moon's mass.

Ganymede

Like Europa, Ganymede shows evidence of a liquid salt-water ocean deep under its icy surface, warmed by tidal forces acting on the moon's core.

Structure of Ganymede

The surface is covered in ancient dark patches which are saturated by impact craters, and less ancient lighter patches featuring grooves and ridges. It is not known why these two surface types exist , but it may have something to do with tectonic activity caused by tidal heating.

Craters of Ganymede

Ganymede features a very thin oxygen atmosphere, the result of water ice on its surface being broken down by radiation from Jupiter.

Mountain Building (Important Facts) {Part-4}

THE PROCESS INVOLVED in mountain building - termed Orogenesis - occur as a result of the movement of the Earth's crustal plates. There are 3 main types of mountains:

1. Volcanic Mountains
2. Fold Mountains
3. Block Mountains

Volcanic Mountains

Fold Mountains

Block Mountains

Most Volcanic Mountains have been formed along plate boundaries where plates have come together or moved apart and lava and debris have been ejected onto the Earth's surface. The lava and debris may have built up to form a dome around the vent of a volcano.

Fold mountains are formed where plates push together and cause the rock to buckle upwards.

Where ocean crust meets less dense continental crust, the oceanic crust is forced under the continental crust. The continental crust is buckled by the impact.This is how folded mountain ranges, such as the Appalachian Mountains in North America, were formed.

Appalachian Mountains

Fold mountains are also formed where two areas of continental crust meet.The Himalayas, for example, began to form when India collided with Asia, buckling the sediments and parts of the oceanic crust between them.

Himalayas Formation

Block mountains are formed when a block of land is uplifted between two faults as a result of compression or tension in the Earth's crust. Often, the movement along faults has taken place gradually over millions of years. However, two plates may cause an earthquake by suddenly sliding past each other along a faultline.

Earthquakes