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Type: Prelims Only

  • International Space Agencies – Missions and Discoveries

    Iron inside the Sun is more opaque than expected

    Prelims Only | Science Tech | Mains Paper 3: Achievements Of Indians In S&T

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Iron Inside the Sun

    Why in the News?

    Recent findings have revealed that iron’s opacity inside the Sun may be much higher than previously predicted, challenging current solar models.

    Iron Inside the Sun:

    • Iron makes up approximately 0.14% of the Sun’s mass, which is significantly less than hydrogen (~74%) and helium (~24%).
    • Despite its small percentage, iron plays a crucial role in the Sun’s opacity. In the Sun, opacity influences how energy moves from the core to the surface.
    • The higher the opacity, the more energy is trapped, impacting the Sun’s temperature, density, and fusion rates.

    Highlights of the New Study:

    • A 2025 study published in Physical Review Letters revealed that iron’s opacity in the Sun’s interior is 30-400% higher than previously predicted by models.
    • Researchers exposed a thin iron sample to X-rays and used spectrometers to measure the shadow cast by the sample.
    • By analyzing how strongly the iron absorbed the radiation, they were able to infer the element’s opacity.
    • Significance:
      • This discovery has important implications for how solar models are constructed.
      • By correcting the opacity of iron, models of the Sun’s temperature profile, fusion rates, and energy distribution may need to be revised.
      • This will lead to a more accurate understanding of stellar behaviour and energy transfer.

    Back2Basics: Composition of the Sun

    • The Sun primarily comprises hydrogen and helium, but other elements such as oxygen, carbon, neon, and iron also play significant roles.

    Element

    Composition by Mass (%)

    Key Role
    Hydrogen (H) 74% The primary fuel for nuclear fusion in the Sun’s core. It undergoes fusion to form helium, releasing energy that powers the Sun.
    Helium (He) 24% A byproduct of hydrogen fusion, helium helps maintain the Sun’s stability and supports continued fusion processes.
    Oxygen (O) ~0.8% Oxygen contributes to the Sun’s opacity, assisting in the transport of energy within the star. It also plays a role in nucleosynthesis, where heavier elements are formed in the Sun’s core.
    Carbon (C) ~0.3% Carbon is involved in nucleosynthesis and plays a significant role in determining the Sun’s opacity and energy transport mechanisms.
    Neon (Ne) ~0.2% Neon is found in the Sun’s atmosphere and is involved in the absorption of radiation, affecting the Sun’s energy output and behavior.
    Iron (Fe) ~0.14% Although small in mass, iron significantly impacts the Sun’s opacity, scattering and absorbing radiation, which influences energy transfer. Iron’s opacity affects the Sun’s temperature, density, and fusion rates.

     

    [UPSC 2002] Which one of the following statements is correct with reference to our solar system?

    (a) The Earth is the densest of all the planets in our solar system

    (b) The predominant element in the composition of Earth is silicon

    (c) The Sun contains 75 per cent of the mass of the solar system

    (d) The diameter of the Sun is 190 times that of the Earth

     

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  • International Space Agencies – Missions and Discoveries

    ESA’s Biomass Mission

    Prelims Only | Science Tech | Mains Paper 3: Awareness in various sc and tech fields

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Biomass Mission

    Why in the News?

    The European Space Agency (ESA) is preparing to launch Biomass Mission to map the world’s forests and enhance our understanding of their crucial role in the global carbon cycle.

    ESA's Biomass Mission

    About the Biomass Mission by ESA

    • The ESA will launch the Biomass mission on April 29, 2025, aboard the Vega C rocket from French Guiana.
    • The mission aims to map the world’s forests, gathering data on their role in the carbon cycle and how they change over time.
    • It will be placed in a sun-synchronous orbit (SSO) at around 666 km, optimizing sunlight for observations.
    • It is the 7th mission in ESA’s Earth Explorer Program, focusing on data related to Earth’s atmosphere, hydrosphere, and land surface.

    Features of the Biomass Mission:

    • Biomass uses a P-band Synthetic Aperture Radar (SAR) sensor (70 cm frequency), capable of penetrating forest canopies to measure carbon storage in trees and the forest floor.
    • It will be the first satellite to use this cutting-edge P-band SAR technology, offering unprecedented forest biomass data.
    • Equipped with a 12-meter antenna, the satellite will deploy upon launch to conduct broad Earth observations.
    • It will create 3D images of forests, from canopy to roots, providing detailed insights into forest health and carbon storage.

    Significance of the Biomass Mission:

    • The mission will fill critical gaps in forest biomass and height data, improving understanding of forests’ role in the carbon cycle and climate change.
    • Biomass will measure carbon storage in forests and track changes due to deforestation and human activity.
    • The mission’s data will aid climate change mitigation strategies by tracking carbon fluxes between forests and the atmosphere.
    • It will support environmental monitoring, assist policymakers, and contribute to global climate change strategies.
    [UPSC 2010] Consider the following statements:

    The Satellite Oceansat-2 launched by India helps in

    1. estimating the water vapour content in the atmosphere.

    2. predicting the onset of monsoons.

    3. monitoring the pollution of coastal waters.

    Which of the statements given above is/are correct?

    (a) 1 only (b) 2 and 3 only (c) 1 and 3 only (d) 1,2 and 3

     

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  • Innovation Ecosystem in India

    [pib] Cu-Phen Metallo-Nanozymes and its Applications

    Prelims Only | Science Tech | Mains Paper 3: Achievements Of Indians In S&T

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Metallo-Nanozymes

    Why in the News?

    Researchers from the CSIR-Central Leather Research Institute (CLRI), Chennai has developed a new nanozyme, Cu-Phen, using a catalyst-by-design strategy. A nanozyme is a type of synthetic enzyme made from nanomaterials (extremely tiny particles) that can mimic the function of natural enzymes in biological systems.

    About the Metallo-Nanozymes 

    • Cu-Phen (Copper-Phenylalanine) is a type of metallo-nanozyme developed by Indian researchers.
    • It is a synthetic enzyme that mimics the functions of natural enzymes in the body, particularly in controlling the flow of energy at the cellular level.
    • It is made by combining copper ions (Cu²⁺) with phenylalanine, an amino acid, using a special design method called “catalyst-by-design”.
    • It forms a self-assembled nano-structure with a well-defined active site, which is where the enzyme’s function occurs.
    • This structure helps Cu-Phen control the electron transfer process, which is important for many biological functions.
    • Unlike traditional nanozymes, which often have poorly defined active sites, Cu-Phen has a precisely structured active site, allowing it to work more efficiently like natural enzymes in the body.
    • Cu-Phen interacts with cytochrome c, a protein that plays a key role in the electron transport chain, which is part of how our body generates energy.
    • It helps reduce oxygen to water without producing harmful substances called reactive oxygen species (ROS), which can damage cells.

    Potential Applications

    • Cu-Phen could be used to make energy systems more efficient, like in bioenergy (energy from living things), by mimicking natural energy-making processes.
    • It could help treat diseases like neurodegenerative diseases and cancer by controlling energy production in cells and reducing harmful effects on the body.
    • These nanozymes can help clean water and make energy systems work better, while reducing pollution and harmful by-products.
    • Cu-Phen can also be used in factories to help make useful products like medicines and chemicals by working like artificial enzymes.
    • This new nanozyme is a step forward in creating artificial enzymes that could be used in many areas like medicine, energy, and manufacturing.
    [UPSC 2022] Consider the following statements :

    1. Other than those made by humans, nanoparticles do not exist in nature.

    2. Nanoparticles of some metallic oxides are used in the manufacture of some cosmetics.

    3. Nanoparticles of some commercial products which enter the environment are unsafe for humans.

    Which of the statements given above is/are correct ?

    (a) 1 only (b) 3 only (c) 1 and 2 (d) 2 and 3

     

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  • Global Geological And Climatic Events

    What are Mesoscale Convective System (MCS)?

    Prelims Only | Enviro & Biodiversity | Mains Paper 1: Salient Features Of World’S Physical Geography

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Mesoscale Convective System

    Why in the News?

    A recent study in Nature Geoscience suggests that soil moisture levels could help predict severe thunderstorms, like mesoscale convective systems (MCSs), especially in regions like India.

    About Mesoscale Convective Systems (MCS):

    • MCSs are larger than individual thunderstorms but smaller than larger weather systems like cyclones.
    • They typically cover areas between 100 to 1,000 km in diameter.
    • They form when warm, moist air rises, creating storms that feed off each other, growing in size and intensity as they move across the region.
    • They can cause flash floods, damaging winds, and severe thunderstorms, and are often responsible for large-scale weather events.
    • In tropical regions, MCSs account for 50 to 90 % of total rainfall, making them a major cause of severe weather-related damage.
    • A notable example is the March 2024 thunderstorm in West Bengal, which caused significant property damage and loss of life.

    Soil Moisture’s Role in MCS as per the Study:

    • Shifts in soil moisture can be detected two to five days before the formation of storms, providing critical lead time for early warnings in vulnerable regions.
    • Contrasting soil moisture levels over large areas (hundreds of kilometers) lead to changes in atmospheric conditions, including A notable example is the March 2024 thunderstorm in West Bengal, which caused significant property damage and loss of life.
    • Larger contrasts in moisture content between dry and wet regions cause greater temperature differences, which in turn lead to changes in wind direction and speed.
    • These variations contribute to turbulence, making storms more intense and spreading rainfall over a wider area.
    [UPSC 2013] During a thunderstorm, the thunder in the skies is produced by the

    1. meeting of cumulonimbus clouds in the sky 2. lightning that separates the nimbus clouds 3. violent upward movement of air and water particles

    Select the correct answer using the codes given below:

    (a) 1 only (b) 2 and 3 (c) 1 and 3 (d) None of the above produces the thunder

     

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  • Global Geological And Climatic Events

    Hadean Protocrust

    Prelims Only | Geography | Mains Paper 1: Salient Features Of World’S Physical Geography

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Hadean Protocrust

    Why in the News?

    A study from Macquarie University, Australia, suggests that plate tectonics may have started earlier than previously thought, with signs of it possibly existing in the Hadean protocrust even before the plates began to move.

    What is Hadean Protocrust?

    • The Hadean protocrust is the Earth’s first crust, formed within the first 200 million years of the planet’s creation.
    • During this time, the surface was mostly molten and constantly hit by space rocks, making it very hot and unstable.
    • Over time, parts of the molten surface began to cool and solidify, creating the first crust.

    Hadean Protocrust

    Back2Basics: Hadean Aeon

    • The Hadean Aeon is the earliest geological eon in Earth’s history, lasting from about 4.6 billion to 4 billion years ago.
    • The surface was incredibly hot and volcanic activity was widespread, often described as “hellish.”
    • It was followed by the Archean Eon (about 4 billion to 2.5 billion years ago), characterized by the formation of Earth’s first stable crust, the beginning of plate tectonics, and the earliest known forms of life.
    • As the surface cooled, the thick parts of the crust formed the first continents, which moved on the hot, semi-fluid layer beneath them called the asthenosphere.

    Key Findings of the Recent Study:

    • The researchers found that the chemical signatures linked to plate tectonics might have appeared earlier, even when the Earth’s crust was still forming in the Hadean protocrust.
    • This discovery suggests that early movements of the Earth’s crust, similar to plate tectonics, could have happened before plates began to move as we know them today.
    • The study used models and experiments to support these ideas, but further research is needed to confirm these findings.
    [UPSC 2013] Which of the following are responsible for bringing dynamic changes on the surface of the earth?

    1. Electromagnetic radiation 2. Geothermal energy 3. Gravitational force 4. Plate movements 5. Rotation of the earth 6. Revolution of the earth

    Which of the above are responsible for bringing dynamic changes on the surface of the earth?

    (a) 1 only (b) 2 and 3 only (c) 2, 4 and 6 only (d) 2 and 4 only

     

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  • Historical and Archaeological Findings in News

    PM Modi at Jaya Sri Maha Bodhi

    Prelims Only | History | Mains Paper 1: Arts & Culture

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Jaya Sri Maha Bodhi Tree

    Why in the News?

    PM Narendra Modi recently visited the Jaya Sri Maha Bodhi temple in the historic city of Anuradhapura, Sri Lanka.

    About the Jaya Sri Maha Bodhi Tree

    • The Jaya Sri Maha Bodhi tree is considered the oldest living cultivated plant globally.
    • It is believed to have grown from a branch of the original Bodhi Vruksha in Bodhgaya under which Gautam Buddha attained enlightenment.
      • This branch was carried to Sri Lanka by Sanghamitra, eldest daughter of Emperor Ashoka and his first wife, Queen Devi.
      • The original tree under which Buddha meditated was reportedly destroyed, possibly by Ashoka’s wife Tishyarakshita in some legends.
    • Sanghamitra’s arrival in Sri Lanka with the tree is commemorated during the Uduvapa Poya, a festival observed annually on a full moon night in December.

    Legend of Sanghamitra’s Journey to Sri Lanka

    • Sanghamitra, originally named Ayapali, lived from 282 BC to 203 BC.
    • Following the Third Buddhist Council (held in 250 BC in Pataliputra) during Ashoka’s reign, it was decided to send missionaries to various regions, including Sri Lanka, to spread Buddhism.
    • The mission to Sri Lanka was led by Mahinda (Mahendra), Ashoka’s son, who converted King Devanampiya Tissa of Anuradhapura to Buddhism.
    • After several royal ladies expressed interest in joining the Buddhist monastic order, Mahinda sent for his sister, Sanghamitra, to initiate them.
      • Both siblings lived in Anuradhapura for the rest of their lives.
    • She played a pivotal role in establishing the Order of Nuns (Bhikkhuni Sangha or Meheini Sasna) in Sri Lanka, which later spread to other Theravada Buddhist countries like Burma, China, and Thailand.
    [UPSC 2020] With reference to the religious history of India, consider the following statements:

    1. Sthaviravadins belong to Mahayana Buddhism. 2. Lokottaravadin sect was an offshoot of Mahasanghika sect of Buddhism. 3. The deification of Buddha by Mahasanghikas fostered the Mahayana Buddhism.

    Which of the statements given above is/are correct?

    (a) 1 and 2 only (b) 2 and 3 only (c) 3 only (d) 1, 2 and 3

     

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  • Railway Reforms

    PM inaugurates New Pamban Bridge 

    Prelims Only | Economics | Mains Paper 3: Infrastructure: Energy, Ports, Roads, Airports, Railways Etc.

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Pamban Bridge

    pamban bridge

    Why in the News?

    The newly constructed Pamban Bridge was inaugurated by PM Modi to replace a 110-year-old structure that connected Rameswaram to the Indian mainland.

    About the Pamban Bridge  

    • The Pamban Bridge, completed in 1914, was India’s first sea bridge, connecting Rameswaram on Pamban Island to the mainland.
    • It featured a double-leaf bascule span, allowing ships to pass through when the bridge lifted.
    • Standing 12.5 meters above sea level and spanning 145 piers, the bridge faced challenges, including cyclones and workforce issues.
    • The old bridge had become unsafe due to severe corrosion and structural weaknesses, highlighted by vibrations detected in 2022.
    • The new bridge features a vertical lift span that can raise in just 5 minutes, with a 22-meter clearance to allow larger vessels to pass, compared to the old bridge’s 1.5 meters.
    • Trains can now travel at speeds up to 75 km/h, a significant improvement from the previous 10 km/h limit.

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  • Cyber Security – CERTs, Policy, etc

    CAPTCHA: a digital border between Humans and Bots

    Prelims Only | Security Issues | Mains Paper 3: Cyber Security

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: CAPTCHA

    Why in the News?

    This newscard is an excerpt from the original article published in The Hindu.

    What is CAPTCHA?

    • CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart.
    • It is a security measure used to differentiate humans from automated bots on websites.
    • It helps protect websites against spam and misuse by ensuring that the user performing actions is a human.
    • It was developed in the early 2000s by Luis von Ahn, Manuel Blum, Nicholas J. Hopper, and John Langford as a response to the proliferation of automated bots on the internet that created fake accounts, spammed websites, and stole data.
    • The first patent for CAPTCHA was filed in 2003.

    How Does CAPTCHA Work?

    • CAPTCHA presents tasks that are easy for humans to solve but hard for machines.
    • These tasks typically involve recognizing distorted text, images, or sounds that machines cannot interpret as reliably as humans.
    • It operates on the principle of the Turing test, designed by British mathematician Alan Turing in the 1950s.
      • This assesses a machine’s ability to exhibit human-like behaviour.
    • Over the years, CAPTCHA has evolved from simple text recognition to more complex tests:
    1. Image Recognition CAPTCHA: Users are asked to identify specific objects within images, such as cars, traffic lights, or storefronts.
    2. reCAPTCHA: Launched by Google in 2009, this system not only serves as a CAPTCHA but also helps digitize text from scanned documents. Users transcribe words that OCR software has been unable to recognize.
    3. Invisible reCAPTCHA: Introduced by Google in 2014, this version analyzes the user’s interaction with the website, such as mouse movements, to determine if they are human without needing them to complete a specific challenge.

    Limitations of CAPTCHA

    • Accessibility Issues: CAPTCHA can be challenging for people with disabilities, such as visual or hearing impairments.
    • User Inconvenience: The need to solve CAPTCHAs can be cumbersome, particularly on mobile devices, and may detract from user experience.
    • Advancing Bot Technology: As bots become more sophisticated with AI, they are increasingly capable of bypassing CAPTCHA systems, necessitating more complex solutions.
    [UPSC 2019] Consider the following statements: A digital signature is

    1. an electronic record that identifies the certifying authority issuing it

    2. used to serve as a proof of identity of an individual to access information or server on Internet.

    3. an electronic method of signing an electronic document and ensuring that the original content is unchanged

    Which of the statements given above are correct?

    (a) 1 and 2 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3

     

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  • Telecom and Postal Sector – Spectrum Allocation, Call Drops, Predatory Pricing, etc

    India’s Subsea Cable Infrastructure

    Prelims Only | Economics | Mains Paper 3: Infrastructure: Energy, Ports, Roads, Airports, Railways Etc.

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Undersea Cables

    Why in the news?

    India is gradually expanding its undersea cable infrastructure, with new systems like Airtel’s 2Africa Pearls and SEA-ME-WE-6 boosting its international internet bandwidth.

    What are Undersea Cables?

    • Undersea cables are fiber optic cables laid on the ocean floor that connect internet networks between countries.
    • These cables are heavily insulated and contain fiber optic strands for transmitting data.
    • They surface at landing points, connect to landing stations, and then link to broader terrestrial networks.
    • Approximately 600 undersea cables exist globally.
    • These cables handle 90% of global data, 80% of world trade, and $10 trillion in financial transactions.

    India’s Current Undersea Cable Ecosystem:

    • India’s two main hubs for subsea cables are Mumbai and Chennai.
      • 17 international cables land in India, with 95% of subsea cables concentrated in a 6-km stretch in Versova, Mumbai.
    • India has two domestic cable systems:
    1. Chennai–Andaman–Nicobar Islands (CANI)
    2. Kochi–Lakshadweep Islands
    • While current bandwidth is considered sufficient, rising data traffic may soon outpace available capacity.
      • Experts warn that India’s current capacity may become inadequate in the near future.
    • India contributes only 1% of global cable landing stations and 3% of subsea cable systems, highlighting its underrepresentation in the global network.

    [UPSC 2016] With reference to ‘LiFi’, recently in the news, which of the following statements is/are correct?

    1. It uses light as the medium for high speed data transmission.

    2. It is wireless technology and is several times faster than ‘WiFi’.

    Select the correct answer using the codes given below:

    (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2

     

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  • Indian Army Updates

    Exercise INDRA 2025

    Prelims Only | Security Issues | Mains Paper 3: Various Security Forces, Agencies & Their Mandates

    Note4Students

    From UPSC perspective, the following things are important:

    Prelims level: Exercise INDRA 2025

    Why in the News?

    The bilateral naval exercise INDRA 2025 between the Indian and Russian navies was held from 28 March to 02 April 2025.

    About Exercise INDRA

    • INDRA is a biennial joint military exercise that began in 2003.
    • Over time, INDRA transformed into a tri-service exercise involving Army, Navy, and Air Force, making it more comprehensive and multifaceted.
    • Recent Editions of INDRA:
      • 2021 (12th Edition): Held in Volgograd, Russia; Focused on counter-terrorism operations and enhancing operational synergy.
      • 2023 (13th Edition): Conducted in the Bay of Bengal, India; Involved naval forces from both countries, enhancing maritime cooperation and joint operations.
      • 2025 (14th Edition): It is being conducted in two phases: Harbour phase at Chennai and Sea phase in the Bay of Bengal.

    Strategic Importance 

    • The exercise reinforced jointmanship between the Indian and Russian forces, strengthening their ability to collaborate in maritime security operations.
    • It highlighted the shared commitment to upholding maritime order and promoting global peace and stability.
    • Best practices were exchanged, fostering a deeper understanding of each other’s operational doctrines and enhancing the capacity to respond effectively to contemporary maritime security challenges.

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