Alaknanda Galaxy | 03 Dec 2025

Source:IE 

Why in News?  

Researchers at National Centre for Radio Astrophysics - Tata Institute of Fundamental Research (NCRA–TIFR), Pune, have discovered a well-structured spiral galaxy named Alaknanda, dating back to just 1.5 billion years after the Big Bang.

• Found using the NASA’s James Webb Space Telescope (JWST), this finding challenges current models, which state that well-structured galaxies do not form so early in the universe’s history 

What are the Key Facts About Alaknanda Galaxy? 

• About: Alaknanda is located about 12 billion light-years away and shows a textbook spiral structure. It formed when the universe was only about 10% of its current age, roughly 1.5 billion years old. 
  • It has two clear spiral arms and a bright central bulge, strikingly similar to the Milky Way. 
  • Named after the Himalayan river Alaknanda, considered the sister river of Mandakini, which is also the Hindi name for the Milky Way.  
    • The name reflects its resemblance to a distant sister of the Milky Way. 
• Significance:  Early galaxies were expected to be chaotic, clumpy, hot, and unstable, but Alaknanda stands out as a mature and well-ordered spiral system. 
  • Its structure adds to growing evidence that the early universe was far more evolved than previously believed.  
  • The galaxy’s unexpected maturity suggests that complex galactic structures began forming much earlier than current models predict. 

What are the Key Facts About the Galaxy? 

• About: Galaxies are immense systems made up of stars, planets, and huge clouds of gas and dust, all held together by gravity.  
  • Their sizes vary widely from small galaxies with only a few thousand stars to giant ones containing trillions of stars and stretching over a million light-years. 
  • Most large galaxies host supermassive black holes at their centers, some weighing billions of times the Sun’s mass. 
  • Galaxies are generally classified as spiral, elliptical, or irregular, based on their structure and appearance. 
• Galaxies in the Cosmic Web: Galaxies gather into groups of up to 100 members, while larger clusters can contain thousands.  
  • These clusters link together to form superclusters, which make up the vast cosmic web of galaxies, voids, and large-scale structures. 
• Key Processes in Galaxy Evolution: 
  • Spiral Structures & Bars: Many mature spiral galaxies develop stellar bars, temporary dense bands of stars that connect to spiral arms and influence star formation. 
  • Collisions: When galaxies collide, gas clouds compress, triggering new star formation, and each galaxy deforms under gravitational forces. 
  • Mergers: Colliding galaxies may merge into a single larger system, often transforming their shapes and sometimes forming ring galaxies or fueling central black holes. 
  • Galactic Cannibalism: Larger galaxies can gradually absorb smaller ones, stripping their gas, dust, and stars and adding them to their own structure. 
• Milky Way Galaxy:  The Milky Way is a spiral galaxy more than 100,000 light-years across. Earth lies along one of its spiral arms, about halfway from the center. 
  • The Milky Way belongs to the Local Group, a collection of over 50 galaxies that includes several dwarfs and the large Andromeda Galaxy.  
    • This group sits near the Virgo Cluster and forms part of the vast Laniakea Supercluster, a major structure within the cosmic web. 
  • Our solar system takes about 240 million years to orbit the Milky Way just once.