Note4Students
From UPSC perspective, the following things are important :
Prelims level: Udham Singh
Mains level: Jallianwala Bagh massacre and its aftermath

December 26 was the birth anniversary of freedom fighter Udham Singh, who is known for avenging the Jallianwala Bagh massacre of 1919.
Try this PYQ:
Q.The Ghadr (Ghadar) was a –
(a) Revolutionary association of Indians with headquarters at San Francisco.
(b) Nationalist organization operating from Singapore
(c) Militant organization with headquarters at Berlin
(d) Communist movement for India’s freedom with head-quarters at Tashkent
Who was Udham Singh?
- Singh, born in Sunam in Punjab’s Sangrur district in 1899, was a political activist who got associated with the Ghadar Party while in the US.
- The multi-ethnic party was believed to have communist tendencies and was founded by Sohan Singh Bhakna in 1913.
- Headquartered in California, the party was committed to the ouster of the British from India.
- In 1934, Singh made his way to London with the purpose of assassinating O’Dwyer, who in 1919 had been the Lieutenant Governor of Punjab.
Why did he consider O’Dwyer responsible for the massacre?
- O’Dwyer ordered Brigadier Reginald Dyer to Amritsar before the massacre; he was worried that there might be a second Indian mutiny, given the Hindu-Muslim unity and the demonstrations and strikes.
- Instead of Dyer, O’Dwyer is considered to be the actual perpetrator, since Dyer could not have executed it without his permission.
- On March 13, 1940, Udham Singh shot O’Dwyer at a meeting of the East India Association and the Royal Central Asian Society at Caxton Hill.
- He was immediately arrested and held in Brixton prison and was sentenced to death and was hanged on July 31, 1940, at Pentonville Prison.
A legend in India
- For avenging the Jallianwala Bagh massacre, Singh is seen by many as a hero. Gandhi, though, had famously called Singh’s revenge as an “act of insanity”.
- While being on trial, he referred to himself as Mohamed Singh Azad, to symbolize Hindu-Sikh-Muslim unity in the fight for India’s freedom.
- In 1974, his remains were sent back to India and he was cremated in his village in Sunam.
- There have been several demands in the past few years for Udham Singh’s statue to be installed in Jallianwala Bagh and the Parliament complex.
- In 2018, his statue was installed at Jallianwala Bagh during Baisakhi.
- Udham Singh Nagar district in Uttarakhand is named after the freedom fighter.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: BBX11 gene
Mains level: Genetics and its applications
Researchers at the Indian Institute of Science Education and Research (IISER) have identified a gene that facilitates in the greening of plants.
It would be no surprise to expect a core Biology question in the coming years, if we look at this PYQ:
Q. Which of the following statements are correct regarding the general difference between plant cells and animal cells? (CSP 2020)
- Plant cells have cellulose cell walls whilst animal cells do not.
- Plant cells do not have plasma membrane unlike animals cells which do
- Mature plant cell has one large vacuole whilst animal cell has many small vacuoles
Select the correct answer using the given code below-
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
BBX11
- The synthesis of chlorophyll in plants is a lengthy, multi-step process.
- When a seedling emerges from under the soil it must quickly synthesize chlorophyll to start supporting its own growth.
- In order to facilitate the quick synthesis of chlorophyll, plants make a precursor of chlorophyll called ‘protochlorophyllide’ in the dark, which glows red when blue light is shone on the plant.
- As soon as the plant comes out into the light from under the soil, light-dependent enzymes convert protochlorophyllide to chlorophyll.
- The two proteins oppositely regulate the ‘BBX11’ gene to maintain optimum levels of ‘BBX11’.
How does it work?
- It plays a crucial role in regulating the levels of protochlorophyllide — an intermediate in the biosynthesis of the green pigment chlorophyll.
- The amount of protochlorophyllide synthesized needed to be proportional to the number of enzymes available to convert them to chlorophyll.
- If there is an excess of free protochlorophyllide, then exposure to light converts it into molecules that cause ‘photobleaching’.
- Thus, it is very important to regulate the amount of protochlorophyllide synthesized by the plant and here comes the vital plant played by the ‘BBX11’ gene.
- If it is less, plants are unable to efficiently ‘green’ in order to harvest sunlight.
Benefits of the research
- The study could have tremendous implications in the agriculture sector in tropical countries like India and can help provide leads to optimize plant growth under stressful and rapidly changing climatic conditions.
- Due to the rapidly changing climatic conditions, farmers in several states in India, especially in Maharashtra, are suffering huge losses in crop yields.
- This often leads to severe distress among the farming community as indicated by the high number of farmer suicides in Maharashtra for the past several years.
- Severe drought, high temperature and high light are some of the major reasons for crop failure. Young seedlings emerging out of the soil are extremely sensitive to high irradiance of light.
- This study can provide leads to optimize plant growth under these stressful conditions.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Ammoni compounds and its uses
Mains level: Not Much
Two persons died and several took ill in a major ammonia gas leakage at a fertilizers unit at Prayagraj.
Try this PYQ:
Q. With reference to chemical fertilizers in India, consider the following statements:
- At present, the retail price of chemical fertilizers is market-driven and not administered by the Government.
- Ammonia, which is an input of urea, is produced from natural gas.
- Sulphur, which is a raw material for phosphoric acid fertilizer, is a by-product of all oil refineries.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 2 only
(d) 1,2 and 3
Ammonia
- Ammonia is critical in the manufacturing of fertilizers and is one of the largest-volume synthetic chemicals produced in the world.
- More than 80 per cent of ammonia made is consumed in the manufacturing of fertilizer, and most of the remainder goes into the production of formaldehyde.
- A tri-hydroid of nitrogen (NH3), ammonia is a building block for ammonium nitrate (NH4NO3) that is used in agriculture as a high-nitrogen fertilizer.
Why is it harmful?
- According to experts in Chemistry, ammonia is stored for industrial use in liquid form under high pressure or in gaseous form at low temperature.
- In such cases, the cause of death is always suffocation as in the case of Prayagraj incident, the victims must have been very close to the point of a gas leak.
Effects on the human body
- Ammonia, even in moderate concentration, can cause irritation to eyes, skin, nose and throat.
- It interacts immediately upon contact with moisture present in the skin, eyes, oral cavity, and respiratory tract to form ammonium hydroxide.
- It is very caustic and disrupts the cell membrane lipids, ultimately leading to cellular destruction.
- As cell proteins break down, water is extracted, resulting in an inflammatory response that causes further damage.
Secretion in humans
- Ammonia, which is highly soluble in water, is found in soil, air, and water; it is naturally present in the body.
- It is secreted by the kidneys to neutralize excess acid.
- However, it is highly diluted when in the environment and does not affect the human body to a noticeable level.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Navratnas of Akbar
Mains level: Medieval arts and culture

This newscard is an excerpt from the original article published in The Hindu.
Try this PYQ:
Q.With reference to Mian Tansen, which one of the following statements is not correct?
(a) Tansen was the title given to him by Emperor Akbar.
(b) Tansen composed Dhrupads on Hindu gods and goddesses.
(c) Tansen composed songs on his patrons.
(d) Tansen invented many Ragas.
Who was Rahim?
- Dating back to 1598, during the rule of Akbar, Abdur Rahim Khan I Khanan was one of the Navratna in the court.
- Winning wars with his military training and hearts with his dohas and translated texts — he was a man who survived despite his father Bairam Khan’s assassination when he was just four.
- Meant to be a dedication of a husband to his wife, the tomb ended up housing his own remains too when he died in 1627.
His works
- Apart from writing various dohas, Rahim translated Babar’s memoirs, Baburnama from Chagatai language to the Persian language, which was completed in 998 (1589–90) AD.
- He had an excellent command over the Sanskrit language.
- In Sanskrit, he wrote two books on astrology, Khetakautukam and Dwatrimshadyogavali.
Why in news?
- The tomb is in a run-down situation but undergoing renovation.
- The historical and cultural significance is more than the archaeological and architectural significance, so restoring the dignity of the burial place has been very important.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Visva-Bharati University
Mains level: Nationalist education during freedom struggle
The Visva-Bharati University established by Gurudev Rabindranath Tagore has completed its centenary.
Do you remember the scheme of education by Gandhi Ji, called Nai Talim?
Visva-Bharati University
- The university was set up by Nobel laureate Rabindranath Tagore in 1921 at Santiniketan, Bolpur in West Bengal’s Birbhum district.
- It was founded by Rabindranath Tagore who called it Visva-Bharati, which means the communion of the world with India.
- Until independence, it was a college. Soon after independence, the institution was given the status of a central university in 1951 by an act of the Parliament.
Its establishment
- The origins of the institution date back to 1863 when Debendranath Tagore was given a tract of land by the zamindar of Raipur, the zamindar of Kirnahar.
- He set up an ashram at the spot that has now come to be called chatim tala at the heart of the town.
- The ashram was initially called Brahmacharya Ashram, which was later renamed Brahmacharya Vidyalaya.
- It was established with a view to encouraging people from all walks of life to come to the spot and meditate.
- In 1901 his youngest son Rabindranath Tagore established a co-educational school inside the premises of the ashram.
What makes it special?
- Rabindranath Tagore believed in open-air education and had reservations about any teaching done within four walls.
- This was due to his belief that walls represent the conditioning of the mind.
- Tagore did not have a good opinion about the Western method of education introduced by the British in India; on this subject, Tagore and Gandhiji’s opinion matched.
- So he devised a new system of learning in Visva-Bharati. He allowed students to continue their course till the student and his teacher both are satisfied.
- At Visva-Bharati, if a course demanded by a student is not available, then the university will design a course and bring teachers for that course.
- The university would not be bothered by the consideration of whether there is a demand for the course.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Fastag
Mains level: RFID technology

From January 1, all lanes of National Highways will accept only electronic payments through FASTag.
Fastags work on a unique technology called RFID (Radio Frequency Identification). This has gone unnoticed in several competitive exams. Hence it is still relevant for the aspirants.
Also read
Fastags
- As per Central Motor Vehicles Rules, 1989, since 1st December 2017, the FASTag had been made mandatory for all registered new four-wheelers and is being supplied by the Vehicle Manufacturer or their dealers.
- It has been mandated that the renewal of fitness certificate will be done only after the fitment of FASTag.
- For National Permit Vehicles, the fitment of FASTag was mandated since 1st October 2019.
What is ‘FASTag’?

- FASTags are stickers that are affixed to the windscreen of vehicles and use Radio Frequency Identification (RFID) technology to enable digital, contactless payment of tolls without having to stop at toll gates.
- The tags are linked to bank accounts and other payment methods.
- As a car crosses a toll plaza, the amount is automatically deducted, and a notification is sent to the registered mobile phone number.
How does it work?
- The device employs Radio Frequency Identification (RFID) technology for payments directly from the prepaid or savings account linked to it.
- It is affixed on the windscreen, so the vehicle can drive through plazas without stopping.
- RFID technology is similar to that used in transport access-control systems, like Metro smart card.
- If the tag is linked to a prepaid account like a wallet or a debit/credit card, then owners need to recharge/top up the tag.
- If it is linked to a savings account, then money will get deducted automatically after the balance goes below a pre-defined threshold.
- Once a vehicle crosses the toll, the owner will get an SMS alert on the deduction. In that, it is like a prepaid e-wallet.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Tso Kar Wetland Complex
Mains level: Ramsar wetlands in India

India has added Tso Kar Wetland Complex in Ladakh as its 42nd Ramsar site, which is a second one in the Union Territory (UT) of Ladakh. With this, India now has forty-two Ramsar sites.
Try this PYQ:
In which one among the following categories of protected areas in India are local people not allowed to collect and use the biomass?
(a) Biosphere reserves
(b) National parks
(c) Wetlands declared under Ramsar convention
(d) Wildlife sanctuaries
Tso Kar Wetland Complex
- It is a high-altitude wetland complex, consisting of two principal waterbodies, Startsapuk Tso, a freshwater lake of about 438 hectares to the south, and Tso Kar itself, a hypersaline lake of 1800 hectares to the north.
- It is situated in the Changthang region of Ladakh.
- It is called Tso Kar, meaning white lake, because of the white salt efflorescence found on the margins due to the evaporation of highly saline water.
Ecological significance
- Wetlands provide a wide range of important resources and ecosystem services such as food, water, fibre, groundwater recharge, water purification, flood moderation, erosion control and climate regulation.
- They are, in fact, a major source of water and our main supply of freshwater comes from an array of wetlands which help soak rainfall and recharge groundwater.
- The Tso Kar Basin is an A1 Category Important Bird Area (IBA) as per BirdLife International and a key staging site in the Central Asian Flyway.
- The site is also one of the most important breeding areas of the Black-necked Crane (Grus nigricollis) in India.
Back2Basics: Wetlands
- A wetland is a distinct ecosystem that is flooded by water, either permanently or seasonally, where oxygen-free processes prevail.
- The primary factor that distinguishes wetlands from other landforms or water bodies is the characteristic vegetation of aquatic plants, adapted to the unique hydric soil.
- Wetlands provide a wide range of important resources and ecosystem services such as food, water, fibre, groundwater recharge, water purification, flood moderation, erosion control and climate regulation.
What is the Ramsar Convention?
- The Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat is a treaty for the conservation and sustainable use of such sites.
- The convention, signed in 1971 in the Iranian city of Ramsar, is one of the oldest inter-governmental accords for preserving the ecological character of wetlands.
- Also known as the Convention on Wetlands, it aims to develop a global network of wetlands for the conservation of biological diversity and for sustaining human life.
- Over 170 countries are party to the Ramsar Convention and over 2,000 designated sites covering over 20 crore hectares have been recognised under it.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Caspian Sea
Mains level: Ecocides and their impact

The Caspian is actually a lake, the largest in the world and it is experiencing a devastating decline in its water level that is about to accelerate.
Note the countries bordering the Caspian Sea: Kazakhstan, Russia, Azerbaijan, Iran and Turkmenistan. Or else remember the acronym ‘TARIK(h)’ (Hindi word for date).
You can frame a mnemonic statement of your choice. Do similarly for major lakes and inland seas. But dont let it move over TARIK pe TARIK!
Caspian Sea
- The Caspian Sea is the world’s largest inland body of water, variously classed as the world’s largest lake or a full-fledged sea.
- As an endorheic basin, it lies between Europe and Asia.
- An endorheic basin is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but converges instead into lakes or swamps, permanent or seasonal that equilibrates through evaporation
- Its level is the product of how much water is flowing in from rivers, mostly the mighty Volga to the north, how much it rains and how much evaporates away.
- At the end of the century, the Volga and other northern rivers will still be there.
- However, a projected temperature rise of about 3℃ to 4℃ in the region will drive evaporation through the roof.
Now try this PYQ:
Q.Which of the following has/have shrunk immensely/ dried up in the recent past due to human activities?
- Aral Sea
- Black Sea
- Lake Baikal
Select the correct option using the code given below:
(a) 1 only
(b) 2 and 3 only
(c) 2 only
(d) 1 and 3 only
Why in news?

- By the end of the century, the Caspian Sea will be nine metres to 18 metres lower. That’s a depth considerably taller than most houses.
- The Caspian’s surface is already dropping by 7 cm every year, a trend likely to increase.
- It means the lake will lose at least 25 per cent of its former size, uncovering 93,000 sq km of dry land.
- If that new land were a country, it would be the size of Portugal.
Past strides in its level
- The Caspian Sea has a history of violent rises and falls.
- In Derbent, on the Caucasus coast of Russia, submerged ancient city walls testify to how low the sea was in medieval times.
- Around 10,000 years ago, the Caspian was about 100 metres lower.
- A few thousand years before that it was about 50 metres higher than today and even over spilt into the Black Sea.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: National Farmers’ Day
Mains level: Not Much
National Farmers’ Day, or Kisan Diwas, is celebrated across the country on December 23 to honour India’s farmers.
Do you think that the extraordinary haste with which the farm bills were pushed through both the Houses has created the present crisis?
National Farmers’ Day
- It marks the birth anniversary of the nation’s fifth PM Choudhary Charan Singh.
- In 2001, the government decided to recognise Choudhary Charan Singh’s contribution to the agriculture sector and welfare of farmers by celebrating his birth anniversary as Kisan Diwas.
- Since then, December 23 has been observed as National Farmers’ Day.
- Generally, awareness campaigns and drives are organised across the country to educate people on the role of farmers and their contribution to the economy.
Who was CCS and what was his connection with farmers?
- Chaudhary Charan Singh, who briefly served as PM between 1979 and 1980, is widely regarded as one of the country’s most famous peasant leaders.
- He was known for his pioneering work to promote the welfare of farmers and the agricultural sector.
- Charan Singh was no stranger to the struggles faced by the Indian farmer. He was born into a middle-class peasant family in Uttar Pradesh on December 23, 1902.
- Greatly influenced by the teachings of Mahatma Gandhi, he took an active part in the fight for independence.
- After that, his political career largely focused on socialism in rural India.
Major legislations
- He was behind several major farmer-forward Bills, including the Land Utilization Bill of 1939 and the Debt Redemption Bill in 1939.
- While serving as agriculture minister in 1952, he led UP in its efforts to abolish the Zamindari system.
- In fact, he went on to draft the UP Zamindari and Land Reforms Bill himself.
- On 23 December 1978, he founded the Kisan Trust — a non-political, non-profit making body — with the aim of educating India’s rural masses against injustice, and fostering solidarity among them.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Matter, Anti-matter
Mains level: Formation of the universe and the Big Bang

This newscard is an excerpt from the original article published in DownToEarth.
Try this PYQ:
Q.The known forces of nature can be divided into four classes, viz, gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not correct?
(a) Gravity is the strongest of the four
(b) Electromagnetism act only on particles with an electric charge
(c) Weak nuclear force causes radioactivity
(d) Strong nuclear force holds protons and neutrons inside the nuclear of an atom.
What is Antimatter?
- Antimatter is the opposite of normal matter. More specifically, the sub-atomic particles of antimatter have properties opposite those of normal matter.
- The electrical charge of those particles is reversed.
- Antimatter was created along with matter after the Big Bang, but antimatter is rare in today’s universe.
- To better understand antimatter, one needs to know more about the matter.
- The matter is made up of atoms, which are the basic units of chemical elements such as hydrogen, helium or oxygen.
Their existence
- The existence of antimatter was predicted by physicist Paul Dirac’s equation describing the motion of electrons in 1928.
- At first, it was not clear if this was just a mathematical quirk or a description of a real particle.
- But in 1932 Carl Anderson discovered an antimatter partner to the electron — the positron — while studying cosmic rays that rain down on Earth from space.
- Over the next few decades’ physicists found that all matter particles have antimatter partners.
- Scientists believe that in the very hot and dense state shortly after the Big Bang, there must have been processes that gave preference to matter over antimatter.
- This created a small surplus of matter, and as the universe cooled, all the antimatter was destroyed, or annihilated, by an equal amount of matter, leaving a tiny surplus of matter.
- And it is this surplus that makes up everything we see in the universe today.
Studying the difference between matter and antimatter
- A Quark is a type of elementary particle and a fundamental constituent of matter.
- Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei.
- The behaviour of quarks, which are the fundamental building blocks of matter along with leptons, can shed light on the difference between matter and antimatter.
- Since they are unstable, they will “decay” — fall apart — into other more stable particles at some point during their oscillation.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Great Indian Bustard
Mains level: Not Much

The Environment Ministry along with the Wildlife Conservation Society (WCS) India has come up with a unique initiative a “firefly bird diverter” for overhead power lines in areas where Great Indian Bustard (GIB) populations are found in the wild.
Try this PYQ:
Q.Which one of the following groups of animals belongs to the category of endangered species?
(a) Great Indian Bustard, Musk Deer, Red Panda, Asiatic Wild Ass
(b) Kashmir Stag, Cheetah, Blue Bull, Great Indian Bustard.
(c) Snow Leopard, Swamp Deer, Rhesus Monkey, Saras (Crane)
(d) Lion Tailed Macaque, Blue Bull, Hanuman Langur, Cheetah
Great Indian Bustard

- The GIB is one of the heaviest flying birds and can weigh up to 15 kg which grows up to one metre in height.
- In July 2011, the bird was categorised as “critically endangered” by the International Union for Conservation of Nature (IUCN).
- It is considered the flagship grassland species, representing the health of the grassland ecology.
- For long, conservationists have been demanding to secure this population, warning that the bird might get extinct in the coming decades.
- It would become the first mega species to disappear from India after Cheetah in recent times.
- Till the 1980s, about 1,500-2,000 Great Indian Bustards were spread throughout the western half of India, spanning eleven states.
- However, with rampant hunting and declining grasslands, their population dwindled.
Bird Diverters

- The diverters are called fireflies because they look like fireflies from a distance, shining on power lines in the night.
- GIBs are one of the heaviest flying birds in India. Therefore, when they encounter these wires, they are unable to change the direction of their flight.
- Death is most cases is due to impact with the wires and not due to electrocution.
- The diverter will not only save GIB but other species of large birds, including migratory birds.
Why such a move?
- GIB is one of the most critically threatened species in India, with less than 150 birds left in the wild.
- A report has pointed out that power lines, especially high-voltage transmission lines with multiple overhead wires, are the most important current threat for GIBs in the Thar region.
- They are causing unsustainably high mortality in about 15% of their population.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Winter Solstice
Mains level: Summer and Winter Solstice

Yesterday, December 21, was Winter Solstice, the shortest day of the year in the Northern Hemisphere. In the Southern Hemisphere, conversely, it was Summer Solstice, the year’s longest day.
Try this MCQ:
Q.On 21st June, the Sun
(a) Does not set below the horizon at the Arctic Circle
(b) Does not set below the horizon at Antarctic Circle
(c) Shines vertically overhead at noon on the Equator
(d) Shines vertically overhead at the Tropic of Capricorn
Why are the hours of daylight, not the same every day?
- The explanation lies in Earth’s tilt.
- And it’s not just the Earth — every planet in the Solar System is tilted relative to their orbits, all at different angles.
- The Earth’s axis of rotation is tilted at an angle of 23.5° to its orbital plane.
- This tilt — combined with factors such as Earth’s spin and orbit — leads to variations in the duration of sunlight than any location on the planet receives on different days of the year.
Impact of the tilted axis
- The Northern Hemisphere spends half the year tilted in the direction of the Sun, getting direct sunlight during long summer days.
- During the other half of the year, it tilts away from the Sun, and the days are shorter.
- Winter Solstice, December 21, is the day when the North Pole is most tilted away from the Sun.
- The tilt is also responsible for the different seasons that we see on Earth.
- The side facing the Sun experiences day, which changes to night as Earth continues to spin on its axis.
Un-impacted regions
- On the Equator, day and night are equal. The closer one moves towards the poles, the more extreme the variation.
- During summer in either hemisphere, that pole is tilted towards the Sun and the polar region receives 24 hours of daylight for months.
- Likewise, during winter, the region is in total darkness for months.
Celebrations associated with the Winter Solstice
- For centuries, this day has had a special place in several communities due to its astronomical significance and is celebrated in many ways across the world.
- Jewish people call the Winter Solstice ‘Tekufat Tevet’, which marks the start of winter.
- Ancient Egyptians celebrated the birth of Horus, the son of Isis (divine mother goddess) for 12 days during mid-winter.
- In China, the day is celebrated by families coming together for a special meal.
- In the Persian region, it is celebrated as Yalda or Shab-e-Yalda. The festival marks the last day of the Persian month of Azar and is seen as the victory of light over darkness.
- Families celebrate Yalda late into the night with special foods such as ajeel nuts, pomegranates and watermelon, and recite works of the 14th century Sufi poet Hafiz Shirazi.
In Vedic tradition
- In Vedic tradition, the northern movement of the Earth on the celestial sphere is implicitly acknowledged in the Surya Siddhanta.
- It outlines the Uttarayana (the period between Makar Sankranti and Karka Sankranti). Hence, Winter Solstice is the first day of Uttarayana.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Kosi River
Mains level: Floods in India

The Bihar government will try to divert the course of the mighty Kosi River in Bhagalpur district to save an archaeological site discovered recently.
Tap to read more about the Himalayan Drainage System:
Drainage System | Part 3
Kosi River: The Sorrow of Bihar
- The Kosi is a trans-boundary river which flows through Tibet, Nepal and India.
- The river crosses into northern Bihar, India where it branches into distributaries before joining the Ganges near Kursela in Katihar district.
- Its unstable nature has been attributed course changes and the heavy silt it carries during the monsoon season, and flooding in India has extreme effects.
- It is also known as the “Sorrow of Bihar” as the annual floods affect about 21,000 km2 of fertile agricultural lands thereby disturbing the rural economy.
Why change its course?
- Several priceless artefacts have been found at the Guwaradih village in Naugachhia sub-division of Bhagalpur district during the excavation of a mound.
- These items could be 2,500-years-old and could be of interest for historians if conserved.
- The historical sites are facing threats from the Kosi floods.
- The Kosi currently flows around 300-400 metres from the site, while its old course is about two kilometres from the village.
Threats posed by the move
- Environmentalists have warned that changing the Kosi’s course could be disastrous for Bihar as seen in 2008.
- At that time, the river had breached its mud embankments at Kushaha in Nepal.
- The Kosi frequently changes its course naturally. If its course is artificially changed, it will cause floods and erosion in new areas, leading to massive displacement of people.
- It then caused extensive damage to life and property downstream in five densely populated districts of northeast Bihar.
- Some 500 people were killed and four million rendered homeless.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Chillai Kalan
Mains level: Not Much
People in the Kashmir valley are finding unique ways to celebrate the start of ‘Chillai Kalan’, a local term for the 40-day period of harshest winter that begins annually from December 21.
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Festivals, Dances, Theatre, Literature, Art in News
Chillai Kalan
- Chillai Kalan is the coldest 40-day period of harsh winter of winter in the Jammu and Kashmir region.
- It is traditionally defined as a seasonal period of harsh winter accompanied by a change in increase in both frequency and quantity of precipitation usually snow.
- It begins from December 21 and ends on January 31 next year.
- It is followed by a 20-day long Chillai-Khurd (small cold) that occurs between January 31 and February 19 and a 10-day long Chillai-Bachha (baby cold).
- According to Persian tradition, the night of 21st December is celebrated as Shab-e Yalda-“Night of Birth”, or Shab-e Chelleh “Night of Forty”.
Its’ celebration
- In the Persian tradition, the night of December 21, the longest of the year, is celebrated as Shab-e-Yalda (night of birth) or Shab-e-Chelleh.
- Dozens of netizens from Kashmir named it the ‘Pheran Day’, after the long woollen gown worn during the winters in Kashmir.
- Use of a traditional firing pot called Kangri increases.
- Tap water pipelines partially freeze during this period. The Dal Lake also freezes.
- The famous tourist resort of Gulmarg receives heavy snow which attracts skier’s from every part of the world.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Khudiram Bose
Mains level: Various revolutionary activities

Union Home Minister has visited the native village of Bengali revolutionary Khudiram Bose in Midnapore, West Bengal.
One of the youngest leaders of the Independence movement, Khudiram Bose is highly regarded in Bengal for his fearless spirit. He was just 19 when he was hanged!
Who was Khudiram Bose?
- Bose was born in 1889 at a small village in Midnapore district.
- From his adolescent years, he was drawn towards revolutionary activities, being inspired by a series of public lectures given by Sri Aurobindo and Sister Nivedita, when the duo visited Midnapore in the early 1900s.
- In 1905, when Bengal was partitioned, he actively participated in protests against the British.
- At the age of 15, Bose joined the Anushilan Samiti, an early 20th-century organisation that propounded revolutionary activities in Bengal.
- Within a year, he had learnt how to make bombs and would plant them in front of police stations.
Revolutionary activities
- The deciding moment of Bose’s life came in 1908 when he along with another revolutionary, Prafulla Chaki was assigned the task of assassinating the district magistrate of Muzaffarpur, Kingsford.
- Before being transferred to Muzaffarpur, Kingsford was a magistrate in Bengal.
- His tortuous clamping down on revolutionaries had earned him the ire of this young group of nationalists who decided to hurl a bomb on him.
Kingsford’s assassination attempt
- There were multiple attempts to assassinate Kingsford.
- Initially, the plan was to throw the bomb in the court. However, after much deliberation, it was decided to avoid the court since a lot of civilians might get injured.
- Thereafter, on April 30, 1908, Bose threw a bomb on a carriage which he suspected was carrying Kingsford.
- But it turned out that it was carrying the wife and daughter of a barrister named Pringle Kennedy, who lost their lives, as Kingsford escaped.
Arrest and execution
- By midnight the entire town was aware of the incident and the Calcutta police were summoned to catch the duo.
- Bose was arrested from a railway station called Waini where he had reached the next morning after having walked 25 miles.
- Chaki on the other hand, killed himself before he could get arrested.
- As Bose was brought handcuffed to the police station at Muzaffarpur, the entire town crowded around to take a look at the teenaged boy.
- On July 13, 1908, he was finally sentenced to death.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: IMAC
Mains level: India's maritime security
India is looking at integrating more countries into coastal radar network IMAC.
What is IMAC?

- The Indian Navy’s IMAC located in Gurugram which was set up after the 26/11 Mumbai terror attacks is the nodal agency for maritime data fusion.
- It functions under the National Maritime Domain Awareness (NMDA) Project.
- The NMDA project was launched in accordance with the vision of PM on SAGAR (Security and Growth for All in the Region).
- The IMAC monitors movement of more than 120,000 ships a year passing through the Indian Ocean.
- The cargo carried by these ships accounts for 66 per cent of world crude oil, 50 per cent of container traffic and 33 per cent of bulk cargo.
- Thus, IMAC performs a very crucial role in collecting shipping information, analysing traffic patterns and sharing the inputs with the user agencies.
Mission SAGAR, unlike other missions, can create confusion with the name and its purpose. Make note of such special cases. UPSC can ask such questions as one liner MCQs.
Expanding IMAC
- It is meant to enable real-time monitoring of the high seas for threats as also expand India’s assistance for capacity building to Indian Ocean littoral states.
- Efforts are in advanced stages to set up coastal radar stations in Maldives, Myanmar and Bangladesh.
- Mauritius, Seychelles and Sri Lanka have already been integrated into the country’s coastal radar chain network.
- Similar plans are in the pipeline with Maldives and Myanmar and discussions are ongoing with Bangladesh and Thailand.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Conjunction in space-phenomena
Mains level: Not Much

After nearly 400 years, Saturn and Jupiter – the two largest planets in our solar system – will be brought closest in the night sky by an astronomical event called the “great conjunction” and popularly referred to as the “Christmas Star”.
Try this PYQ:
What is a coma, in the context of Astronomy?
(a) Bright half of material on the comet
(b) Long tail of dust
(c) Two asteroids orbiting each other
(d) Two planets orbiting each other
What are the Conjunctions?
- A conjunction is not unique to Saturn and Jupiter however, it is the name given to any event where planets or asteroids appear to be very close together in the sky when viewed from the Earth.
- In June 2005 for instance, as a result of the “spectacular” conjunction, Mercury, Venus and Saturn appeared so close together in the sky that the patch of sky where the three planets were could be covered by a thumb.
- Astronomers use the word “great” for the conjunction of Jupiter and Saturn because of the planets’ sizes.
The “Great Conjunction”
- It happens once in about 20 years because of the time each of the planets takes to orbit around the Sun.
- Jupiter takes roughly 12 years to complete one lap around the Sun and Saturn takes 30 years.
- This is because Saturn has a larger orbit and moves more slowly because it is not as strongly influenced by the Sun’s gravitational force as planets that are closer to the Sun.
- As the two planets move along their orbits, every two decades, Jupiter catches up with Saturn resulting in what astronomers call the great conjunction.
A ‘rare alignment’
- Jupiter and Saturn are bright planets and can be typically seen with the naked eye even from cities.
- But during conjunction, they appear to be close to each other, which is what makes the event noteworthy.
- The event will coincide with the winter solstice (shortest day of the year in terms of hours of sunlight received) in the Northern Hemisphere and summer solstice in the Southern Hemisphere.
- This year, however, the event is rare because the planets will come the closest to each other in nearly four centuries; in what astronomer Henry Throop described is a result of a “rare alignment” of the planets.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Koothambalam
Mains level: Keralan Architecture

The renovated Koothambalam of the Sreekrishna temple, Guruvayur, has been selected for the UNESCO Asia-Pacific Award for cultural heritage conservation.
Try this PYQ:
Q. Building ‘Kalyana Mandapas’ was a notable feature in the temple construction in the kingdom of-
(a) Chalukya
(b) Chandela
(c) Rashtrakuta
(d) Vijayanagara
What is Koothambalam?
- Koothambalam meaning temple theatre is a closed hall for staging Koothu, Nangiar koothu and Koodiyattam, the ancient ritualistic art forms of Kerala.
- Koothambalams are said to be constructed according to the guidelines given in chapter 2 of Nātyasāstra of Bharata Muni.
- The stage within the hall is considered to be as sacred as the temple sanctum.
Its’ construction
- It is constructed within the cloister of the Temple; more precisely within the pancaprakaras of the temple. The prescribe location is between the prakaras of bahyahara and maryada.
- In Kerala tradition, it is considered as one among the panchaprasadas of a temple complex.
- Its dimension varies from temple to temple.
- A square platform with a separate pyramidal roof supported by pillars in the centre called natyamandapam is constructed as s separate structure within the large hall of Koothampalam.
- The floor of the hall is divided into two equal halves and one part is for performance (including stage, instruments, green room etc.) and another half for seating audience.
About Guruvayur Temple

- It is a Hindu temple dedicated to the Hindu lord, Guruvayurappan (a four-armed form of the Lord Vishnu), located in the town of Guruvayur in Kerala.
- It is one of the most important places of worship for Hindus in Kerala and is often referred to as Bhuloka Vaikunta (Holy Abode of Vishnu on Earth).
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: CMS-01
Mains level: Not Much

The Indian Space Research Organisation (ISRO) successfully placed into a transfer orbit India’s 42nd communications satellite, CMS-01, carried onboard the PSLV-C50.
CMS-01
- It is a communications satellite envisaged for providing services in extended C Band of the frequency spectrum and its coverage will include the Indian mainland and the Andaman & Nicobar and Lakshadweep islands, the ISRO.
- The satellite is expected to have a life of over seven years.
- It was injected precisely into its pre-defined sub- geostationary transfer orbit (GTO).
- CMS-01 is considered to be a replacement of the aged satellite GSAT-12. It provides services like tele-education, tele-medicine, disaster management support and Satellite Internet access.
What is GTO?

- A geosynchronous transfer orbit or geostationary transfer orbit (GTO) is a type of geocentric orbit.
- Satellites which are destined for geosynchronous (GSO) or geostationary orbit (GEO) are (almost) always put into a GTO as an intermediate step for reaching their final orbit.
- A GTO is highly elliptic.
- Its perigee (closest point to Earth) is typically as high as low Earth orbit (LEO), while its apogee (furthest point from Earth) is as high as geostationary (or equally, a geosynchronous) orbit.
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Note4Students
From UPSC perspective, the following things are important :
Prelims level: Icebergs
Mains level: Impact of climate changes on Cryosphere

A research mission is held to find out the impact of a giant floating iceberg A-68s on the wildlife and marine life on a sub-Antarctic island.
Q. How does the cryosphere affect global climate? (CSM 2017)
What are Icebergs?
- An iceberg is a large piece of freshwater ice that has broken off a glacier or an ice shelf and is floating freely in open (salt) water.
- Small bits of disintegrating icebergs are called “growlers” or “bergy bits”.
- Much of an iceberg is below the surface which led to the expression “tip of the iceberg” to illustrate a small part of a larger unseen issue.
- Icebergs are considered a serious maritime hazard, especially for shipping industries.
A-68s
- The iceberg — named A-68s — is travelling at varying speeds depending on local conditions, but at its fastest was travelling about 20 kilometres a day.
- The huge iceberg — the size of the U.S. state of Delaware — has been floating north since it broke away from Antarctica’s Larsen C ice shelf in 2017.
- It is now about 75 kilometres from the island of South Georgia, and scientists are concerned over the risks it poses to the wildlife in the area if it grounds near the island.
- South Georgia is home to colonies of tens of thousands of penguins and 6 million fur seals, which could be threatened by the iceberg during their breeding season.
- The waters near the island are also one of the world’s largest marine protected areas and house more marine species than the Galapagos.
- Destruction by the iceberg will release this stored carbon back into the water and, potentially, the atmosphere, which would be a further negative impact.
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