Aurorae in Ladakh | 18 Oct 2024

Source: TH 

Why in News? 

Recently, auroras were sighted in lower-latitude regions (below 66.5 degrees north and south latitudes) like India (Hanle and Merak in Ladakh), Mexico and Germany. 

• Their occurrence in lower-latitude regions is an indication of heightened solar activity. 

What are the Key Highlights About Aurora Sightings? 

• Aurora and Peak Solar Cycle: Auroras occur when coronal mass ejections (CMEs) interact with Earth’s Magnetosphere.  
  • Coronal mass ejections (CMEs) are part of the solar activity cycle, which lasts around 11 years.  
  • The current solar cycle called Solar Cycle 25 is at its peak in 2024.  
• Lower Latitude Aurora: A severe solar storm, initially classified as a level 4 on a scale from 1 to 5, is the reason for aurora sightings in lower-latitude regions. 
  • It typically appears in northern regions like Canada, Norway, Sweden, Finland, Alaska, Russia, Iceland, and Greenland.  
    • Severe solar storms can trigger auroras and accelerate satellite decay, while extreme storms may destroy satellites, disrupt power grids, and cause widespread communication blackouts. 

What are Key Facts About Auroras? 

• About Aurora: An aurora is a mesmerising natural light display visible in the night sky, often characterised by shifting colours such as blue, red, yellow, green, and orange. 
  • The more common green-yellow auroras result from ions striking oxygen atoms at lower altitudes. 
  • Reddish and bluish lights, seen in the lower edges of auroras, are caused by ions interacting with nitrogen atoms. 
  • Collisions with hydrogen and helium atoms can produce blue and purple auroras, but these colours are rarely visible to the naked eye. 
• Geographical Occurrence: Auroras are most commonly seen near the Arctic and Antarctic Circles, approximately 66.5 degrees north and south of the Equator. 
  • The northern aurora is called the aurora borealis (northern lights), while the southern counterpart is known as aurora australis (southern lights). 
• Cause of Auroras: Auroras are caused when charged particles from solar storms interact with the Earth’s magnetosphere, which acts as a shield against harmful solar and cosmic rays. 
  • Solar storms occur when the Sun's magnetic field intensifies and weakens, allowing charged particles to penetrate the Earth's magnetic field. 
• Role of Solar Wind and Earth's Magnetosphere: Auroras form when charged ions from the solar wind collide with oxygen and nitrogen atoms in the Earth's ionosphere, usually at altitudes between 97 and 1,000 kilometers. 
  • The Earth's magnetosphere deflects most of the solar wind, but some ions get trapped near the geomagnetic poles, creating these stunning light displays. 

• Scientific Study of Auroras: NASA’s IMAGE satellite, which operated until 2005, was designed specifically to study auroras. 
  • Using ultraviolet and radio waves, IMAGE gathered important data on how auroras form and behave. 
• Aurora on Other Planets: Planets with an atmosphere and magnetic field likely experience auroras. 
  • E.g., Stunning auroras have been observed on Jupiter and Saturn.