Sunday, 14 March 2021

Difference between an Air-Conditioner and an Air-Cooler

I am seeing lots of Air Coolers advertisements for many years. Many outlets are also selling them without giving an important reason. They're actually hiding those for their sales. 

 

Air Coolers are humidifiers technically. They induce humidity in dry areas like those places in interior like Salem, Vellore, Nagpur, Delhi etc. Where room AC won't help while a central AC can help. Interior areas have very less humidity, so they’ll feel hot. When we induce humidity, we feel a cooling effect as humidity goes up.

 

Whereas in coastal areas, air conditioners will help and work as they dehumidify the air. Because the coastal areas have lots of humidity, it needs to be reduced. When reduced, we feel a cooling effect as AC will also suck moisture on your skin. 

 

While a central AC is a different animal. It is a hybrid of Air cooler and an air-conditioner. 

 

One thing, if you have low or high blood pressure, have cardiac issues, please be careful when you come out of an AC room. Temperature difference between inside and outside during peak summer will be drastic. It will take time for your body to adjust. That gap may kill you as changes/ shift will be sudden & extreme and body will try to adjust by trying to rush blood on emergency to skin and brain. But it can't do that instantly. So heart is put onto maximum strain and it may lead to cardiac arrest or even a brain stroke. 

 

In 2000/2001 I experienced that physically. I was shopping in Spencer's. Mall was 22° C and immediate outside temperature was 43° C. A difference of almost 21° C, my body struggled to adjust and I was about to get knocked down unconscious. 

 

Especially people with comorbidities, aged should be careful in an air-conditioned environment. Same effect may be felt in reverse during winters.

 

The Air Conditioners maintain an ambient temperature of 20 to 24° C. During winters, many areas experience colder temperatures, the room temperature will be pretty warm and outside temperature will be cold. This difference in temperature may also induce similar health issues I marked above.   

 

In French the Air Conditioner is called CLIMATISEUR & for Air Coolers REFROIDISSEUR D’AIR which says their original intended usage and purpose.

Monday, 11 May 2020

Bangladesh Railway

 

Bridges, Borders, and the Forgotten Rails: The India–Bangladesh Frontier Revisited

Prelude: The Divided Tracks of the East

 

The story of Bengal’s railways is, in many ways, a tale of belonging and bereavement. Few other regions in the subcontinent witnessed such an abrupt severing of iron and emotion. Once, the rhythmic pulse of trains traversed unbroken through these lands, from the bustling terminus of Calcutta to the distant halts of Chittagong and Assam. Then came 1947 — the year of Partition — and the rhythm faltered. What was once a seamless network became a cartographer’s casualty.

In the decades that followed, border stations turned into ghostly outposts. Platforms that had once greeted travellers and traders were left to the mercy of vines, silence, and nostalgia. Yet, the steel never forgot its purpose. Even when dormant, it remembered — waiting patiently for a time when connections might once again outpace divisions.


Rails Between Realms: The Haldibari–Chilahati Legacy

Amongst the many dismembered lines of the eastern frontier, the Haldibari (India)–Chilahati (Bangladesh) corridor remains emblematic of both interruption and endurance. Once part of the grand Siliguri–Calcutta main line, these stations lay on the venerable broad gauge track that stitched together the northern plains with the port city of Calcutta.

At Partition, Haldibari fell within India’s Cooch Behar district, while Chilahati drifted into East Pakistan. Still, the trains ran — a fragile continuity — until the Indo-Pak War of 1965, when all cross-border railway movement in the eastern corridor came to an abrupt halt.

The distance between Haldibari and the international border is a mere 4.5 kilometres, while Chilahati lies 7.5 kilometres from the zero point on the Bangladeshi side. By the early 2020s, work on the Indian side had been nearly completed — more than 95 per cent of track-laying done — with progress on the Bangladeshi side dictating the pace of completion. The restoration of this link promises more than just connectivity; it represents the revival of a memory long buried under political dust.


Metre-Gauge Memories: Bengal’s Narrower Arteries

In earlier decades, the Bengal frontier was laced with metre-gauge lines that carried not only freight but also the pulse of small-town life. The Radhikapur–Biral–Parbatipur and Changrabandha–Burimari branches once linked West Bengal to northern Bangladesh — fragments of the Lalmonirhat–Malbazar line, developed in the twilight years of the nineteenth century by the Bengal Dooars Railway.

When Partition came, the Indian side terminated at Changrabandha and the Pakistani side at Burimari. Today, the Radhikapur–Biral–Parbatipur section has been upgraded to broad gauge, while Changrabandha–Burimari remains a name whispered among the abandoned corridors of railway lore.


Lalmonirhat and the Lost Corridors of Connection

By the turn of the nineteenth century, Lalmonirhat had emerged as a railway citadel in north Bengal — a vital junction from which iron veins stretched to Assam and beyond. Two metre-gauge corridors once linked this region with Cooch Behar:

  • Lalmanirhat–Mogalhat–Dharla River Bridge–Gitaldaha, and

  • Bamanhat–Golokganj, both facilitating seamless travel from Bengal to Assam.

The GitaldahaMogalhat crossing, divided by the Dharla River, is today but a spectral reminder. Mogalhat lies on the Bangladeshi side in Lalmonirhat District, while Gitaldaha — now defunct — sits quietly in India’s Cooch Behar. A new Gitaldaha station was later built further north, feeding into the Bamanhat line.

Before independence, a single 1,000 mm wide metre-gauge artery connected Fakiragram (Assam) to Katihar (Bihar) via Radhikapur, Biral, Parbatipur, Kaunia, Tista, Gitaldaha, Bamanhat, and Golokganj. This line, operated by the Eastern Bengal Railway, was the principal route to Assam’s Amingaon Port from Semaria Ghat in Bihar — a lifeline of trade and travel that spanned the heart of the subcontinent.


Assam’s Gateway Through Bengal

Until the 1960s, a modest but important line linked Cooch Behar to Dhubri (Assam) via Golokganj, known as the Assam Line Railway Service. Remarkably, even after Partition, this route continued through East Pakistan between Bamanhat and Golokganj, embodying a rare continuity amid division.

The Sonahat crossing, another forgotten rail transit point, once connected Golokganj to Kurigram by metre gauge. Over time, floods, neglect, and shifting political sands erased this link from the living map.

Notably, the Assam Mail — immortalised in the 1943 Bradshaw’s India Time Table — plied this network, running from Katihar to Tinsukia Junction, with a slip pair joining from Calcutta at Parbatipur. In those days, the railway was the subcontinent’s bloodstream: from Awadh to Assam, from Chittagong to Tinsukia, the iron roads of Eastern Bengal carried a civilisation in motion.


Mahisasan–Shahbajpur: The Silent Frontier of the North-East

Further east, the Mahisasan–Shahbajpur (Latu) link between Assam’s Karimganj district and Bangladesh’s Sylhet region once served as a critical metre-gauge corridor. The line connected Mahisasan to Karimganj, eleven kilometres apart, and was operational until the 1965 war severed ties.

In the 1950s, international trains ran between Kulaura (East Pakistan) and Badarpur (India) on this very gauge, with rolling stock belonging to the Eastern Bengal Railway. Today, the line lies in disuse, its sleepers overtaken by weeds — a once-bustling gateway now a border relic.


New Corridors of Hope: The Tripura Connection

If the older links are memories, Tripura is the promise of renewal. Two new cross-border connections are poised to transform the North-East’s railway geography:

  • Agartala (India) – Gangasagar (Bangladesh), and

  • Belonia (India) – Feni (Bangladesh).

The Agartala–Gangasagar line, spanning 15.6 kilometres, includes 10.6 km on the Indian side (up to Nischintapur) and 5.46 km connecting Nischintapur to Agartala station. Nischintapur will host the region’s first trans-shipment yard, where passengers and goods from Bangladesh will interchange — a symbolic and logistical bridge between the two nations.

Once dual-gauging is completed across Bangladesh’s eastern corridor, a direct service between Agartala and Kolkata is envisaged — running via Tangail, the Jamuna Rail Bridge, and the Hardinge Bridge — effectively reuniting the North-East with the eastern seaboard.

By early 2021, work on the Indian side was well underway, the hum of welding torches and concrete mixers replacing the long silence of inactivity.


Over the Jamuna: From Ferry to Bridge

Before the advent of the Bangabandhu Bridge (1996–97), the people of Bangladesh’s central regions depended on rail ferries to traverse the mighty Jamuna (Brahmaputra) River. These ferries were the arteries of connection between the western and eastern halves of the country.

Two major ferry crossings once operated — between Sirajganj Ghat and Jogannathganj Ghat, and between Bahadurabad Ghat and Tistamukh Ghat. The western banks were served by broad gauge lines from Ishurdi, linking eventually to Calcutta, while the eastern banks relied on the metre-gauge system.

The completion of the 4.8-kilometre Bangabandhu Bridge fundamentally altered the nation’s communications landscape. By 2010, the ferry systems at Bahadurabad–Balashi and Jogannathganj–Sirajganj had been phased out, the former succumbing to riverine shoals and siltation. The river’s old channel — tracing its way from the Jamuna’s divergence to the Shitalakshya’s mouth — remains a reminder of the days when ferries were as integral to the railway as the trains themselves.


The Shifting Lines of the East

In the years following the bridge’s completion, a new metre-gauge line was laid from Bangabandhu East station to Taraknandi in 2008, replacing the now-abandoned Taraknandi–Jogannathganj Ghat line on the Jamuna’s banks. This transition symbolised the region’s evolution from a river-dependent system to an integrated rail corridor, uniting the once-distant halves of Bangladesh through engineering vision.

Between Akhaura and Kulaura, the now-defunct Shaistaganj–Habiganj and Kulaura–Latu branches once hummed with life. Today, they rest in quiet disuse, reminders of an era when railways traced every contour of the land, binding together the diverse destinies of Bengal, Assam, and Sylhet.


Epilogue: The Iron Memory

From Haldibari’s sidings to Agartala’s new yard, the story of these lines is not merely one of transport — it is the saga of resilience and remembrance. Borders may have altered geographies, but the railway — that steadfast servant of civilisation — continues to seek reunion.

Every whistle that pierces the silence of the border carries within it the echo of the past — of friendships rekindled, economies revived, and histories reconnected. Steel may age, bridges may corrode, but the railway’s dream remains immutable: to link hearts as much as it links lands.


Coda: The Pulse Beneath the Rust

Across the frontierlands of Bengal and Assam, where rivers shift and rails remember, the old alignments whisper of a past that refuses to fade. Each bridge rebuilt and each sleeper relaid is not merely an act of engineering but a gesture of reconciliation — an attempt to restore continuity where history once drew a line.

Steel may corrode, maps may change, yet the rhythm of the railway endures — steadfast, sonorous, and forgiving. Beneath the rust lies a pulse that still beats for unity.


Glossary

  • Broad Gauge (BG): Railway track spacing of 1,676 mm, the predominant standard in India.

  • Metre Gauge (MG): Narrower track gauge of 1,000 mm, once common across Bengal and Assam before conversion to broad gauge.

  • Eastern Bengal Railway: A pre-Independence railway company operating routes across undivided Bengal and Assam, many of which now traverse modern Bangladesh.

  • Partition (1947): The division of British India into India and Pakistan, which severed many through railway routes in the East.

  • Transit Point: A designated cross-border junction permitting customs and railway interchange between two national systems.

  • Hardinge Bridge: A major railway bridge over the Padma River in Bangladesh, built during British rule (1915).

  • Bangabandhu Bridge: The 4.8-km bridge over the Jamuna River (1996–97) linking western and eastern Bangladesh.

  • Bradshaw: The authoritative British-era railway timetable and guidebook of Indian train services.

  • Fakiragram / Amingaon Port: Historic railway termini in Assam linked by the Eastern Bengal Railway network prior to 1947.


Copyright Notice

© 2020–2026 Dhinakar Rajaram. All rights reserved.
This article, including its text, phrasing, and historical analysis, is the author’s original work. Reproduction, distribution, or adaptation in any form without explicit written consent from the author is strictly prohibited. Quotations or references may be made with proper attribution and citation of the source.


Hashtags


#IndianRailways #BangladeshRailway #EasternBengalRailway #PartitionHistory #RailwayHeritage #HaldibariChilahati #CrossBorderRails #BengalRails #ForgottenFrontiers #DhinakarRajaram

 Bridges, Borders & Forgotten Rails — tracing the lost lines between India and Bangladesh. 🚂
#RailwayHistory #BengalRails #DhinakarRajaram




Thursday, 30 April 2020

108 years old Elephant Gate bridge pulled down!






108 years old Elephant Gate Bridge has been pulled. For past few years traffic was stopped permanently on this bridge and supporting steel rods were erected to hold the bridge as it has gone old and rickety. Secondly, the bridge was 50 metres in length. Which created a chicken neck like situation. Where tracks get squeezed allowing only 6 tracks under it. Before and after the bridge tracks are broad. Resulting in unduly holdups. A train arrives on time or well ahead to perambur or basin bridge, but holdup for 20 to 30 minutes due to this bridge as only 6 trains - 3 up and 3 down can pass any given time. There by affecting the train movements to and fro from Central. Now railways will build a steel bridge of 150 metres, there by giving room to atleast 10 tracks and holdups will be reduced as trains can enter and exist easily. Plans also there to shift west bound trains to Salt Cotaurs as 4th terminal. 

Sunday, 26 April 2020

Is it Day or Night?



Why sky appears blue even in night? What are those two stars above that water tank?   Irrespective of day or night, our atmosphere scatters blue colour. This was found by Sir. Chandrasekhara Venkata Raman, FRS or Sir. C.V. Raman! He was the recipient of the Nobel Prize for Physics in 1930 for the discovery that when light traverses a transparent material, some of the light that is deflected changes in wavelength. This phenomenon is now called Raman scattering and is the result of the Raman effect.  Raman scattering or the Raman effect is the inelastic scattering of a photon. It was discovered by C. V. Raman and K. S. Krishnan in liquids, and by G. Landsberg and L. I. Mandelstam in crystals. The effect had been predicted theoretically by A. Smekal in 1923.  When photons are scattered from an atom or molecule, most photons are elastically scattered (Rayleigh scattering), such that the scattered photons have the same energy (frequency and wavelength) as the incident photons. However, a small fraction of the scattered photons (approximately 1 in 10 million) are scattered by an excitation, with the scattered photons having a frequency different from, and usually lower than, that of the incident photons. In a gas, Raman scattering can occur with a change in energy of a molecule due to a transition . Chemists are concerned primarily with such transitional Raman
 effect.  Those two stars are: binary star system Alpha Centauri AB / Rigil Kent ( 4.39 light years from sun) and Hader / Beta Centauri 525.21 Ly away) to its right is Southern Cross or Crux . above is Libra and to left is Scorpios and Lupus constellations.  If we draw a cross line from between these two stars and draw a line from Acrux or Alpha 1 Crux, both will point to south pole point! There is no specific star pointer for Earth's Southern pole as in North pole where we have Polaris!

Image Settings: F2.8, ISO 100. 30 sec exposure. Taken in 2013.  Camera: Fujifilm Hybrid DSLR.

Monday, 4 November 2019

தமிழ் மருத்துவம் (சித்த மருத்துவம்) Siddha Medicine

இன்னும் எத்தனை  ஆண்டுகள் ஆனாலும், இதுதான் மருந்து, புதிய கண்டுபிடிப்பெல்லாம் கிடையாது.

இந்த பாடலை ஒவ்வொரு வரும் எழுதி வைத்து கொள்ளுங்கள், எக்காலத்திலும் உதவும்.

இப்பாடல் அருந்தமிழ் மருத்துவம் 500 என்ற பாடலில் இருந்து எடுக்கப்பட்டது.

மூளைக்கு வல்லாரை
முடிவளர நீலிநெல்லி
ஈளைக்கு முசுமுசுக்கை
எலும்பிற்கு இளம்பிரண்டை
பல்லுக்கு வேலாலன்
பசிக்குசீ ரகமிஞ்சி
கல்லீரலுக்கு கரிசாலை
காமாலைக்கு கீழாநெல்லி
கண்ணுக்கு நந்தியாவட்டை
காதுக்கு சுக்குமருள்
தொண்டைக்கு அக்கரகாரம்
தோலுக்கு அருகுவேம்பு
நரம்பிற்கு அமுக்குரான்
நாசிக்கு நொச்சிதும்பை
உரத்திற்கு முருங்கைப்பூ
ஊதலுக்கு நீர்முள்ளி
முகத்திற்கு சந்தனநெய்
மூட்டுக்கு முடக்கறுத்தான்
அகத்திற்கு மருதம்பட்டை
அம்மைக்கு வேம்புமஞ்சள்
உடலுக்கு எள்ளெண்ணை
உணர்ச்சிக்கு நிலப்பனை
குடலுக்கு ஆமணக்கு
கொழுப்பெதிர்க்க வெண்பூண்டே
கருப்பைக்கு அசோகுபட்டை
களைப்பிற்கு சீந்திலுப்பு
குருதிக்கு அத்திப்பழம்
குரலுக்கு தேன்மிளகே!
விந்திற்கு ஓரிதழ்தாமரை
வெள்ளைக்கு கற்றாழை
சிந்தைக்கு தாமரைப்பூ
சிறுநீர்க்கல்லுக்கு சிறுகண்பீளை
கக்குவானுக்கு வசம்புத்தூள்
காய்ச்சலுக்கு நிலவேம்பு
விக்கலுக்கு மயிலிறகு
வாய்ப்புண்ணிற்குமணத்தக்காளி
நீர்க்கோவைக்கு சுக்குமிளகுநீர்
நீரிழிவிற்கு ஆவாரைக்குடிநீ்ர்
வேர்க்குருவிற்கு பனைநுங்குநீ
வெட்டைக்கு சிறுசெருப்படையே
தீப்புண்ணா குங்கிலியவெண்ணை
சீழ்காதுக்கு நிலவேம்பு
நாப்புண்ணிற்கு திரிபலாவேலன்
நஞ்செதிர்க்க அவரிஎட்டி
குருதிகழிச்சலுக்கு துத்திதேற்றான்
குருதிகக்கலுக்கு இம்பூரல்வேர்
பெரும்பாட்டிற்கு அத்திநாவல்
பெருவயிறுக்கு மூக்கிரட்டை
கக்கலுக்கு எலுமிச்சைஏலம்
கழிச்சலுக்கு தயிர்சுண்டை
அக்கிக்கு வெண்பூசனை
ஆண்மைக்கு பூனைக்காலி
வெண்படைக்கு பூவரசு கார்போகி
விதைநோயா கழற்சிவிதை
புண்படைக்கு புங்கன்சீமையகத்தி
புழுகுடற்கு வாய்விளங்காமணக்கு
கால்வெடிப்பா மருதாணிகிளிஞ்சல்
கரும்படை வெட்பாலைசிரட்டை
கால்சொறிக்குவெங்காரபனிநீர்
கானாகடிக்கு குப்பைமேனிஉப்பே
உடல்பெருக்க உளுந்துஎள்ளு
உளம்மயக்க கஞ்சாகள்ளு
உடல்இளைக்க தேன்கொள்ளு
உடல் மறக்க இலங்கநெய்யே
அருந்தமிழர் வாழ்வியலில்
அன்றாடம்சிறுபிணிக்கு
அருமருந்தாய் வழங்கியதை
அறிந்தவரை உரைத்தேனே!!

Sunday, 27 October 2019

தீப ஒளிp

தீப ஒளி:

கிட்டத்தட்ட 13800000000 (1380 கோடி) வருடங்களுக்கு முன் பிரபஞ்சம் தோன்றியது. முதல் மூன்று லட்சம் வருடங்களுக்கு "ஒளி" என்ற ஒன்றே இல்லாமல், கும்மிருட்டாக இருந்தது. 

அதன் பிறகு ஹைட்ரஜன் அணுக்கள் உருவாகி இப் பிரபஞ்சத்தின் முதல்  "ஒளி" உமிழப்பட்டது. ஆகவே இந்தப் பிரபஞ்சத்தின் முதல் தீபம்  (பட்டாசு!) ஹைட்ரஜன் (குண்டு) தான் 💙.

பார்த்து ரசிப்பதற்கு என்று ஒருவரும் இல்லாமலே, அணுக்கள் இணைந்து திரள்ந்து மாபெரும் நட்சத்திரங்களாகவும், அதனால் இடம் குழிந்தாழ்ந்து-வளைந்து (Curved Space) ஈர்ப்பு விசையாக மாற, ஈர்ப்பு விசையின் அதீத அழுத்தத்தால் நிலைகுலைந்து 10 கிலோமீட்டர் ஆரமுடைய "பல்சர்" (சுற்றும் நியூட்ரான் ஸ்டார்) உருவாகி, அது இப் பிரபஞ்சத்தின் "சங்கு சக்கரம்" ஆனது!

இப்பொழுதும் பிரபஞ்சத்தில், ஒளியை விட இருட்டுதான் அதிகம். இருள் இருப்பதனாலேயே நம்மால் ஒளியை ரசிக்க முடிகிறது. கோடான  கோடி அணுகுண்டுகள் பிரபஞ்சத்தில் எப்பொழுதும் வெடித்துக்கொண்ட இருக்கின்றன. 

நல்லவேளை பிரபஞ்சம் 99% வெற்றிடமாக இருக்கிறது, இல்லை என்றால் நம் காது எப்பொழுதோ செவிடாயிருக்கும் (அல்லது பரிணாமத்தில் காது என்ற ஒன்று இல்லாமலே போயிருக்கும்).

காசு காரியாகிறது என்று கதைக்காமல், காசு ஒளியாகிறது என்று வானத்தில் கணப்பொழுதில் தோன்றி மறையும் வர்ண ஒளிக் கோலங்களை ரசியுங்கள். இது பிரபஞ்சத்தின் மினி தீபாவளி. 

அனைவருக்கும், என் சார்பாகவும் என் குடுபத்தின் சார்பாகவும்  இனிய தீப ஒளித்திருநாள் நல்வாழ்த்துக்கள் 😊

பி.கு : பிரபஞ்சத்தின் முதல் ஒளியை நீங்கள் பார்க்கவேண்டுமானால், அந்தக் கால டிவியை அன்டெனா இல்லாமல் வெறுமனே ஆன் செய்து, சும்மா உட்க்கார்ந்து கொள்ளுங்கள். அதில் தெரியும் கருப்பு-வெள்ளை புள்ளிகள் தான் பிரபஞ்சத்தின் முதல் ஒளி. ரசிப்பீர்களா என்ன?😉

Wednesday, 10 April 2019

First direct photo of a Black Hole

We all maybe aware a project was on for 20 years to capture a #BlackHole and we were near to that when astronomers captured the orbits of Stars around our parent super massive #BlackHole around #Sagittarius-A Star on the constellation of #Sagittarius.

 They had captured the movement of stars around that Black Hole but were unable to capture the actual black hole.

 Until now Astronomers were able to capture only the superficial evidence of Black Holes like #PlasmaJets etc.

Plasma Jets or Relativistic jets or Astrophysical jet is an astronomical phenomenon where outflows of ionised matter are emitted as an extended beam along the axis of rotation.[1] When this greatly accelerated matter in the beam approaches the speed of light, astrophysical jets become relativistic jets as they show effects from special relativity.

The formation and powering of astrophysical jets are highly complex phenomena that are associated with many types of high-energy astronomical sources. They likely arise from dynamic interactions within accretion disks, whose active processes are commonly connected with compact central objects such as black holes, neutron stars or pulsars. One explanation is that tangled magnetic fields[2] are organised to aim two diametrically opposing beams away from the central source by angles only several degrees wide (c. > 1%).Jets may also be influenced by a general relativity effect known as frame-dragging.

Most of the largest and most active jets are created by supermassive black holes (SMBH) in the centre of active galaxies such as quasars and radio galaxies or within galaxy clusters. Such jets can exceed millions of parsecs in length. Other astronomical objects that contain jets include cataclysmic variable stars, X-ray binaries and gamma-ray bursts (GRB). Others are associated with star forming regions including T Tauri stars and Herbig–Haro objects, which are caused by the interaction of jets with the interstellar medium. Bipolar outflows or jets may also be associated with protostars or with evolved post-AGB stars, planetary nebulae and bipolar nebulae.

Event Horizon Telescope (EHT) project, which captured the epic imagery of the black hole's EVENT HORIZON. Totally four photos were captured, which were unveiled today at press events around the world and in a series of published papers, outline the contours of the monster black hole lurking at the heart of the elliptical galaxy M87 located in constellation of Virgo on Virgo Super Cluster.

The EHT is a consortium of more than 200 scientists who were on this global sized project for about two decades.The project is named after  black hole's famed point of no return — the boundary beyond which nothing, - not even light can escape the object's intense gravitational clutches or EVENT HORIZON.

It's therefore impossible to photograph the interior of a black hole, unless you somehow manage to get in there yourself. (You and your pictures couldn't make it back to the outside world, of course.)
So, the EHT images the event horizon, mapping out the black hole's dark silhouette. (The disk of fast-moving gas swirling around and into black holes emits lots of radiation, so such silhouettes stand out.)

1. Virgo super cluster. M 87 is part of this super cluster. Constellation Virgo



2. M 87




3. Core of M 87. The plasma jet blue coloured is from it's super massive black hole ejecting the gulped stars.





4. Event Horizon Telescope's image of M 87 super massive black hole. First ever direct image of a black hole.







Chandrasekar the nephew of Sir. C V Raman on a sea.voyage in 1930s theorised the star's mass needed for becoming a black hole.

Messier 87 (also known as Virgo A or NGC 4486, generally abbreviated to M87) is a supergiant elliptical galaxy in the constellation Virgo. One of the most massive galaxies in the local Universe,[a] it has a large population of globular clusters—about 12,000 compared with the 150–200 orbiting the Milky Way—and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs (4,900 light-years), traveling at relativistic speed. It is one of the brightest radio sources in the sky, and a popular target for both amateur and professional astronomers.

A detailed video on this by Space.com. Please click this link :


https://www.space.com/first-black-hole-photo-by-event-horizon-telescope.html?fbclid=IwAR0Jq9mDheQ6QPCc7plny32ga6Clnr9bl-aI0KEgMRfgoR8ehjsdJezzWEY&jwsource=cl


Thanks & Courtesy: Space.com, Event Horizon Telescope Project , Wikipedia and other sources from Internet. 

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