Art & Culture
- Sexual Harassment Charges against Chief Justice of India Ranjan Gogoi
- All You Need to know about Electoral Bonds
- Electoral Bonds controversy
- NaMo TV controversy
- General Elections 2019
- RBI Governor bats for a Permanent Status to Finance Commission
- PM Modi’s Mission Shakti Speech & Model Code of Conduct
- Sadhvi Pragya Thakur’s latest Controversy
- Rafale deal document controversy
- Should SC Judges be under RTI ambit?
- Supreme Court Judgement on Tainted Candidates
- VVPAT verification
Governance & Social Justice
- Candida Auris : Drug- resistant fungi
- Candida auris infection
- Healthcare System for India, Difference in USA & European healthcare model?
- Lateral Entry in Civil Services explained
- Model policy for Women in Police
- NIRF India Rankings 2019 declared
- Quality Assurance Scheme
- Sex on false promise of marriage is rape
- Survey 2019 Ambitions Beyond Growth report by UNESCAP
- World Health Statistics Overview 2019 report on Life Expectancy
- World Press Freedom Index 2019
- Supreme Court compensation order on Bilkis Bano case
- WHO guidelines on physical activity for children under 5 years of age
- Global Talent Competitive Index 2019
- Algeria Political Crisis
- EU’s new Copyright Law, Will it change Web Worldwide?
- India Pakistan Kartarpur Corridor Talks
- India to Become NATO Ally?
- Japan Starts a New Era
- Julian Assange Arrested
- Sudan Political Crisis
- Trump designates Islamic Revolutionary Guard Corps of Iran
- United Nations Has to Pay India $38 Million
- US labels Revolutionary Guard of Iran a terror organisation
- US Mexico border wall controversy
- Why is UAE Important for India?
- Why is Chile Important for India?
- India Pakistan Conflict De-escalation Mechanisms
- India suspends cross LoC trade with Pakistan
- What is Arab Spring 2.0?
- India to stop buying Oil from Iran
- Trump withdraws from UN arms treaty
- Asian Development Outlook 2019
- China’s growth after slowdown
- Foreign Investment in India
- India’s 20th Livestock Census
- India’s transition to Renewable Energy from conventional sources
- Indian Army Builds The Longest Bridge of India Over Indus In Leh
- India Energy Modelling Forum by NITI Aayog & USAID
- National Common Mobility Card launched
- Rise and fall of Private Airlines in India
- Rise in Global Crude Oil prices & weakening Rupee
- Slowdown in Industrial Growth & rising Inflation
- Supreme Court order on EPFO
- Supreme Court quashes RBI’s 12 February Circular on NPA
- What are Junk Bonds?
- What is Fixed Maturity Plans?
- What is GDP deflator? Is it more comprehensive compared to WPI and CPI?
- What is Trader’s Credit Card Scheme?
- What is Wholesale Price Index?
- 1st Bimonthly Monetary Policy review – April 2019
- National Rubber Policy 2019
- Sensex hits 7 months high, History & Functions of Bombay Stock Exchange
- Supreme Court orders RBI on RTI
- What is Dedollarisation?
- Asian Tea Alliance
- Pepsico vs Farmers Issue
Defence & Security
Science & Technology
- Dhanush Artillery Guns
- Combat Casualty Drugs
- The Indian Museum of the Earth (TIME)
- EMISAT Satellite Launched
- Faster Adoption & Manufacturing of Hybrid & Electric
- First Ever Image of a Black Hole
- India to Buy MH60 Romeo Helicopters
- Nepal and Sri Lanka Launch Their First Satellites Raavana 1 & NepaliSat-1
- Nirbhay Missile Successfully Tested
- High Bacteriophages in Ganga River
- Army invokes Emergency Powers for Missile Deal
- Cell Based Meat
- INS Imphal Guided Missile Destroyer
- Draft Indian Forest Act 2019
- Gujarat Fishermen’s victory in US Supreme Court
- Humpback Mahseer Fish included in Critically Endangered list by IUCN
- India Cooling Action Plan (ICAP)
- Jammu & Kashmir Environment Issues
- Madras High Court order on Chennai Salem Highway
- Monkey declared Vermin in Himachal Pradesh
- Neelakurinji Flower under Severe Threat
- Solar eWaste
- Special Postal Stamp on Ice Stupas released
- State of Global Climate report 2018
- What is Green Finance Ecosystem?
- Wind turbines are impacting ecology in Western Ghats
- All about Wild Food Plants
Spice of the Month
- GS3 || Science and technology || Space || Miscellaneous
Why in news ?
- The first photograph of a black hole was revealed by scientists recently.
What is a black hole?
- A black hole is an object in space that is so dense and has such strong gravity that no matter or light can escape its pull. Because no light can escape, it is black and invisible.
- There’s a boundary at the edge of a black hole called the event horizon, which is the point of no return — any light or matter that crosses that boundary is sucked into the black hole. It would need to travel faster than the speed of light to escape, which is impossible.
- Anything that crosses the event horizon is destined to fall to the very centre of the black hole and be squished into a single point with infinite density, called the singularity.
If black holes are invisible, how can we detect or photograph them?
- By looking for the effects of their extreme gravity, which pulls stars and gases toward them.
- Also, while anything past the event horizon is invisible, outside that boundary there is sometimes a spiral disk of gas that the black hole has pulled toward — but not yet into — itself.
- The gases in that accretion disk are heated up as they accelerate toward the black hole, causing them to glow extremely brightly. The colours they glow are invisible to us, but are detectable with an X-ray telescope.
- Scientists have also detected the gravitational waves generated when two black holes collide. light surrounding the black hole right to the edge of the event horizon, which is the goal of the Event Horizon Telescope.
How big are black holes?
- Small black holes are called stellar-mass black holes. They have masses similar to those of larger stars — about five to 20 times the mass of the sun. The other kind is supermassive black holes, which are millions to billions of times more massive than the sun. That’s the kind the Event Horizon Telescope has been trying to photograph, as bigger objects ought to be easier to see. There is some evidence that black holes between these two sizes exist, but that has yet to be confirmed.
- While black holes are very massive, that doesn’t mean they take up a lot of space. Because they’re so dense, they’re actually quite small. According to NASA, a black hole 20 times the mass of the sun could fit inside a ball 16 kilometres wide — the width of the Island of Montreal at its widest point.
Where do black holes come from?
- Supermassive black holes are believed to form at the same time as the galaxy that surrounds them, but astronomers aren’t sure exactly how.
- Stellar mass black holes form when a star with a mass greater than three times that of our sun runs out of fuel. It explodes into a supernova and collapses into an extremely dense core that we know as a black hole — something predicted by Albert Einstein’s general theory of relativity.
- Einstein’s theory also predicts the size and shape of the black holes that the Event Horizon Telescope is trying to photograph.
Additional references : https://youtu.be/Ocd_qd4GhO4